There are several types of injection molding machines, including hydraulic, electric, and hybrid machines. Hydraulic machines are the most common and use hydraulic pumps to operate the machine’s movements, including the clamping, injection, and ejection processes. Electric machines use electric motors and servo motors to operate the machine’s movements and are more energy-efficient. Hybrid machines combine hydraulic and electric systems to provide a balance of power and energy efficiency.

When choosing an injection molding machine manufacturer, it is important to consider factors such as the quality and reliability of the machines, the level of customer support and service provided, and the cost of the machines. It is also important to ensure that the manufacturer has the expertise and experience to produce machines that meet your specific production needs and requirements.

In summary, injection molding machines are a crucial part of the plastic manufacturing process, and choosing the right manufacturer is important for ensuring high-quality, reliable machines that can meet your production needs.

plastic injection molding machine

Factors affecting the quality of injection molding

1. Injection pressure: the reason for the need for injection pressure is to offset the resistance in the process of melt flow, or the resistance in the flow process to eliminate the pressure of the injection machine, the two are just the opposite, in order to ensure the smooth progress of the filling environment;

2. Injection time: reasonable injection time is conducive to the ideal filling of the melt, and the ear is very important to improve the surface quality of the product and reduce the dimensional tolerance;

3. Injection temperature: the injection temperature must be controlled within the range of M, the temperature is too low, the plasticization of molten materials is not good, which affects the quality of forming parts and increases the difficulty of processing; If the temperature is too high, the raw material is easy to decompose;

Two, the shortcomings of injection molding process

1, product molding must use injection molding and blow molding two sets of mold and a valve hollow core mold, and the injection mold should be able to withstand high pressure, molding equipment cost is high;

2. The temperature of the injection blank is high, and it needs a long cooling and shaping time after blowing in the injection mold, which prolongs the whole molding cycle of the product and affects the production efficiency.

3. The internal stress of the injection molding blank is large, and it is easy to be subjected to uneven cooling during the transformation of the mold. Stress cracking is easy to occur when producing products with complex shapes and large sizes.

4. The operation skills of the operators are higher

First, the advantages of injection molding process

plastic injection molding machine

1. Injection mold can be used to accurately control the wall thickness distribution of the billet, so that the wall thickness of the container is more uniform, avoiding the thinning phenomenon that is prone to occur in the corner of general blow molding products. The weight of the product can be controlled at +0.1g, the accuracy of the thread can be controlled within the range of 100μM, the mouth size is accurate, and the fine neck product molding precision is high.

2, the obtained products do not need to be processed for E times, no joints, saving the dressing time of the products;

3. The blank made by injection can all enter the blow molding mold, and there is no waste in the process, reducing the waste of forming materials;

4, can get smooth surface products, no scratches, surface text and pattern clear;

5, small batch production can be carried out economically;

6. Wide range of application for plastic varieties;

7, high degree of automation, multi-mode production, high production efficiency.

Before starting, the injection molding machine and auxiliary machine must be inspected to ensure that the equipment is in normal condition (according to the requirements of L1 equipment operation records). If any problems are found, the maintenance personnel should be notified in time.

2.Power supply for injection molding machine

 

Turn on the power supply of the injection molding machine, the mold temperature of the mechanical and electrical source, the general mold temperature is set to 80℃, the drying mechanical and electrical source (raw materials need to be dried at 80℃ for 4 hours), the cold water mechanical and electrical source, the exhaust fan and other power supply, turn on the injection molding machine oil pump motor screw and begin to heat up.

3.Grease is applied to the guide post

Wipe the oil stains on the parting surface, guide post, guide sleeve, slider, cavity and oblique guide post of the die with oiling paper. Apply grease to the surface of guide post, guide sleeve, slider and oblique guide post to prevent the die from wear during long working time.

4.Confirm mold condition

Confirm the mold condition, check whether there is damage, whether the oil circuit is smooth, whether the pipe connection is connected in place, whether there is oil leakage phenomenon.

5.Automatic cleaning key

When the temperature meets the requirements, discharge the material, open the baffle of the feeding port, press the automatic cleaning key of the operation panel of the injection molding machine, and clean the material for 2-3 times. After the completion of the cleaning, clean the remaining material of the nozzle and the mold suction nozzle.

plastic injection molding machine

In 1980, France produced the world’s largest screw injection molding machine, with an injection capacity of 170kg. From the 1980s to recent years, the development of injection molding machine is mainly concentrated in several aspects: namely, the application of precision automatic control system and various auxiliary equipment in automatic molding; Precision machinery and high performance hydraulic system; Various special injection molding machine development and computer aided design of complex shape parts plastic flow analysis to determine the best injection conditions; Application of various energy saving technologies in injection molding machine.

Working principle of injection molding machine

Injection molding machine referred to as injection molding machine, injection molding is the use of plastic thermophysical properties, the material from the hopper into the barrel, the barrel outside by heating ring heating, so that the material melt, in the barrel is equipped with external power motor drive rotation of the screw, the material in the double action of the screw shear gradually plasticized, melting and homogenizing, when the screw rotation, Material in the groove friction force and shear force under the action of the molten material pushed to the head of the screw, at the same time, the screw in the material reaction backward, so that the head of the screw to form a storage space, complete the plasticization process, and then the screw in the injection cylinder piston reasoning under the action of high speed, high pressure, the storage room of the molten material through the nozzle into the mold cavity, After the molten material in the cavity is kept under pressure, cooled and solidified, the mold is opened under the action of the mold closing mechanism, and the finished product is ejected from the mold and dropped through the ejecting device.

Composition structure of injection molding machine

Injection molding machine according to the injection molding process requirements is a mechanical and electrical integration of a strong machine, mainly composed of injection parts, closing parts, frame, hydraulic system, heating system, control system, feeding device and so on.

plastic injection molding machine

At present, the common injection molding device has single cylinder type and double cylinder type.

Plasticized parts have two kinds: plunger type and screw type. In the process of continuous rotation of the screw, the plastic realizes the change of physical state, and is finally injected into the mold cavity in a molten state. Therefore, the plasticized component is the core component to achieve uniform plasticizing and quantitative injection.

To provide customers with plastic products development, mold design, product manufacturing and injection molding, its products are widely used in every field of life today, such as household appliances, instruments, wires and cables, building equipment, communications electronics, automotive industry, aerospace, daily hardware and so on.

The overall production process of plastic products is: raw material selection – raw material coloring and matching – design casting mold – machine decomposition injection molding – printing – assembly detection of finished products – packaging factory.

Plastic products are made by injection molding or blow molding, so every time you design a sample, you have to open a new mold, and the mold is generally tens of thousands to hundreds of thousands of dollars, so in addition to the raw material price of plastic products, the cost of the mold is also very large. There may be many parts to make a finished product, and each part needs a separate mold. For example, the trash can is divided into: the barrel body — the lid, the liner, the handle several parts.

Generally speaking, the plastic factory refers to the processing of plastic products with plastic raw materials, semi-finished products and finished products, such as MP3 shell, telephone shell, mobile phone shell, computer monitor shell and other plastic accessories. And finished products such as plastic cups, plastic washbasins, plastic buckets, and other daily necessities. Its essence is called plastic processing plant.

Why we need to set mold protection to prevent damage? Beside the injection molding machine itself, the second most expensive piece of equipment we use on a daily basis is the mold. If the molds are damaged, you are not only responsible for the cost of maintenance, but also for downtime and labor costs.If done correctly, the mold can rest on something as thin as a business card. Here are three key components for setting up mold protection on injection molding machines:

1. Starting position of mold protection

When do you reach the point in the mold where you might break when the mold is closed? In the figure above, this point is when the mold touches the guide pin. This is where we want to start mold protection; close the die until there is a small gap between the protrusion of the half die and the other half and there is a risk of damage. Then look at the mold location on the controller to see where you want mold protection to start.

2. Position of die protection end

You need to stop protecting the mold if the mold fully closed. This is called the clamping position or die contact position on the machine. Clamp the die in manual die setting mode until there is no gap between the half dies. For the figure above, the mold position is 0.05 inches. So,we must set the jig position on the machine slightly higher than the actual position to protect it.

3. Speed and pressure of mold preservation

And we need to set suitable speed and pressure for the machine,which is allowed to reach during die protection. In general, we are concerned to slow down the holding of the die during this period and set the pressure low enough so that if something gets in the way of the half die, the die will stop the jig motion and emit a jig alarm.

Don’t forget closing pressure is the most important aspect of die protection Settings!

Following these simple steps, you will help protect valuable mold asset.

Contact: kiles020801@gmail.com

Thanks!

1. The forming parts refer to the parts related to the forming cavity of the moving and fixing parts.
2. The pouring system is to melt the plastic
3. Guide part in the injection mold, the guide part is used to guide the dynamic and fixed mold of the mold, so that the mold can be accurately matched when the mold is closed.
4. Push out mechanism refers to the device that pushes out the plastic parts from the mold after parting.
5. In order to meet the requirements of injection process on mold temperature, the temperature regulating system is needed to adjust the temperature of the mold. General thermoplastic injection mold is mainly designed mold cooling system.
6 exhaust system is in order to form the plastic itself volatile gas out of the mold, often in the parting surface open exhaust groove. For small plastic parts of the mold, can directly use parting surface or push rod and mold clearance exhaust.
7. Supporting parts are parts used to install and hold or support the forming parts and the aforementioned parts of the mechanism.
8. Lateral parting and core pulling mechanism is when some plastic parts have lateral concave and convex shape of the hole or boss, must first put the side concave and convex shape of the flap module or the side of the core from the plastic parts off or out.
The passage through which the basic structure of the plastic injection mold passes from the injector nozzle into the mold cavity, as shown in Figure 1-1, includes the main flow channel, diverter channel, gate and cold hole.

(1) Forming part. That is, the cavity part of plastic products formed directly after mold assembly, including punch, concave die, core, rod or insert.

(2) Mold guide part. It is a part set up to align the center shaft correctly when moving and fixing the die, including the guide post, the pilot hole cover, or the inclined conical piece.

(3) Product launching part. The molding injection product is pushed out from the molding cavity, including the ejector rod, the fixing plate, the pushing plate, the pad, etc.

(4) core extraction part. When injection molding plastic products with pits or side holes are demoulded, core mechanism components for pits and side holes forming, such as inclined guide posts, sliding blocks, bending, etc., should be extracted first.

(5) Specific heating and cooling parts of the mold. It refers to the control system suitable for the temperature of injection molding process of plastic products, such as resistance heating plate, rod and electrical control element; Circulating cooling water pipes are used for cooling parts.

 

(6) The specific supporting part of the mold. Refers to dynamic, fixed die plate, positioning ring, lifting ring, various fastening screws and other auxiliary parts, to ensure that the mold can work correctly.

(7) Pouring melt channel. It refers to the channel that can introduce the melt injected by the nozzle into the mold cavity, which can be usually divided into the main channel, the shunt channel, the bushing (gate) and the cold groove.

(8) Exhaust hole. It refers to the air discharge part in the mold cavity. General small products do not need special exhaust holes, the air in the cavity can be discharged from the gap of the accessories; For molds of large injection products, vent holes must be set up.

Only for reference.

Plastic Moulding Advantages

1.Fast

Cycle times can be as low as 10 seconds. Combine that with a multi-impression injection moulding tool and you get a LOT of products very quickly. Generally speaking， it takes a bit longer as it’s a specialist material and has a lot of features to be moulded correctly, but at about 50 seconds you’d still get 70 parts per cavity per hour. CNC machining a one-off would take half a day – 3D printing it even longer!

2. Low cost per part

Whilst there is an initial high investment for the plastic injection molding tool, after that the cost per part is  low. Other plastic processing techniques may require multiple operations, like polishing, whilst injection moulding can do it all at once. If you chose to Guanxin machine the part above, it would cost hundreds of pounds per part. If you’re looking to go into full production, injection moulding is the way to go.

3.Special Surface Finishes, Engraving & Printing

In addition to a range of colours, the injection molding tool can be made with a special finish which will show on the moulding. Just about any finish you like, for example leather look, soft touch, sparked, high shine, you name it. You can also have logos or other text engraved in the tool. Finally, you can have your mouldings printed, as a range of inks are available.

4.High repeatability

Once your mould tool made, identical products can be made over and over again. A decently made mould tool has a very long mould tool life. as long as it’s treated well by the moulding machine setters !

Plastic Moulding Disadvantages

Sounds good right ? Of course there are some disadvantages:

1. High Initial Cost

Several rounds of designing and modelling are needed before the go-ahead or production is given. Then, the injection moulding tool need to make the mouldings will need designing & manufacturing.

2.Careful design needed

Plastic mouldings need very careful design to avoid tooling issues like undercuts, locked-in features and not enough draft. The material and temperature will need to be taken into account in wall design, otherwise the mould may not fill fully. The placement of ejectors and cooling lines will need to be considered to ensure the product is aesthetically pleasing.

 3.Initial lead time

Thanks for reading.

Raw material increase

Labor costs have skyrocketed

Difficulty in recruiting staff

Large turnover of personnel

Product price decline

The problem of increasingly fierce competition in the industry.

I

njection molding industry has entered the era of transformation, small profit and reshuffle, injection molding workshop management needs to establish a “scientific, perfect, systematic, standardized” operation management system, so that “everything is managed, everyone is in charge” of the working atmosphere of the department, for the injection molding workshop each post work efficiency improvement, manpower reduction has the following measures and suggestions:

First, the upper and lower mold workers to improve work efficiency, reduce manpower measures

1. Do a good job in the production planning arrangement to reduce the number of machine replacement due to improper scheduling.

2. Reasonably set the number of thimble and ejection length to reduce the frequency of broken pins in production.

3. To strengthen the process of production mold cleaning, lubrication, the bartender  work, reduce the mold failure rate.

4. Strictly control the phenomenon of die pressing in the process of injection molding and reduce the number of die falling maintenance.

5. Use appropriate tools to take the adhesive parts of the mold, prevent the mold from being injured by careless operation, and reduce the number of mold maintenance.

6. Make the upper and lower mold tool car and the hanging ring waiting equipment positioning storage area, reduce the time to find the upper mold tools.

7. Promote the “fast mold up method” to refine every action of the upper and lower molds and convert internal time into external time.

8. Reduce the clamping force and open locking speed to reduce mold deformation and impact.

9. The mold channel entrance is designed as a sinking hole, and quick joint is used to reduce the time of disassembling and assembling the water nozzle.

2. Measures to improve work efficiency and reduce manpower for mold testers

By improving the level of mold designers, improving the working quality and efficiency of mold testers, and reducing the workload of mold testers, the purpose of reducing mold testers is achieved:

1. Engaged in mold design with mold flow analysis software, optimized mold structure, improved mold runner, gate, cooling, exhaust, demoulding and other effects.

2. Reduce the increase of mold modification, mold repair and mold test caused by mold structure problems

3. Conduct injection molding technology training for mold designers, and give full consideration to material properties, injection molding process requirements and injection molding quality requirements when designing molds

4. Provide injection molding training to mold testers, improve their ability to find, analyze and deal with problems, improve the quality and efficiency of mold testing, and reduce the number of mold testing.

5. Specify the number of new mold test (no more than 3 times)

6. Do a good job of preparation before mold test, choose the appropriate injection molding machine, scientific mold test to shorten the time of mold test, reduce the test modulus.

7. Formulate the process of mold trial, standardize the requirements of mold trial, clarify the purpose of mold trial, increase the responsibility of all departments, and reduce the number of invalid mold trial from the management.

8. Select experienced, professional and responsible personnel for mold trial, shorten the time of mold trial and increase the number of mold sets.

Measures to improve work efficiency and reduce manpower for the personnel of the aircraft transfer

1. Implement automatic and unmanned injection molding to reduce the adjustment caused by the instability of manual boot.

2. Control the ambient temperature of the workshop to achieve the purpose of stable mold temperature, material temperature and injection molding process conditions. (ring)

3. Formulate standard process conditions, arrange production machines reasonably, and ensure the repetition of process conditions. (law)

4. Strengthen the injection process management, prohibit the injection process operators, mold workers, feeding. Staff and other non-technical personnel adjust the machine to prevent process fluctuations and changes in the quality of rubber parts. (people)

5. To do a good job of guaranteed  injection molding machine, to ensure that the repeat precision of injection molding machine and the stability and reliability of the process conditions. (machine)

6. Filter the cooling water to prevent the mold temperature change caused by the rusting of the water channel system resulting in abnormal quality. (machine)

7. Strictly control the quality of raw materials, water inlet materials and pumping granular materials. Water inlet materials need to be recycled after dust screening to prevent the adjustment caused by raw material problems. (material)

8. The preventive maintenance, the use of injection mold,  work, reduce the die failure and rotary die after the fixed mold, machine work. Use special paper to clean the oil on the mold before the mold testing machine, reduce the time of mold testing and save materials.

9. Conduct comprehensive and systematic training of injection molding technical personnel, master the knowledge of material, machine, mold, process and defect analysis, improve their ability to analyze and deal with problems, improve their injection molding technical level and control ability of injection molding process, reduce blind machine adjustment, and take the road of scientific injection molding.

10. For special moulds (such as multi-neutron moulds), precautions should be marked on the moulds to make problems obvious and prevent personnel from making mistakes.

11. The pipe should be cleaned before the shutdown and then cooled, to prevent the material from burning the screw can not be cleaned, use the screw cleaning agent to save the time of cleaning the pipe.

Iv. Measures for ingredients to improve work efficiency and reduce manpower

1. The batching room needs to increase the number of mixer (mixer), the color and the type of plastic material ingredients, equipped with enough and appropriate tools to clean the mixer, improve the efficiency of cleaning the mixer, shorten or reduce the time and workload of cleaning the mixer.

2. If the mixer is more, a variety of materials can be mixed at the same time to reduce the number of ingredients.

3. Change the traditional way of batching by shift, implement single batching, make raw material rack, complete the materials required by the order in one time, reduce the time and workload of cleaning mixer.

4. Do a good job in the ingredients plan and make the ingredients board to prevent the phenomenon of wrong materials and multiple materials. Materials before and after ingredients should be clearly marked to reduce the amount of ingredients by reducing the occurrence of problems.

5. Conduct training for batching staff to improve their working ability, quality and efficiency, so as to achieve the purpose of reducing staff.

6. Use color master, color master proportional valve, edge crusher and central feeding system to cancel the batching link and reduce batching staff.

7. The number of batching staff in one class can be reduced by changing the concept of batching, improving the efficiency of batching, doing well the label of batching and implementing single shift batching.

Five. Feeding staff to improve work efficiency, reduce manpower measures

1. Make suitable feeding ladder to facilitate feeding and improve feeding efficiency.

2. Place the materials to be filled in the designated area according to the machine, and the materials of each machine shall be clearly marked. So as not to add the wrong ingredients.

3. Use edge automatic suction machine instead of manual feeding.

4. Adopt central feeding system and color master proportional valve to realize automatic feeding.

5. Improve the filling bucket and reduce the feeding frequency to reduce the feeding personnel.

Vi. Measures to improve work efficiency and reduce manpower for crushing staff

1. The crusher shall be added to the crusher room, and the crusher shall be divided according to the type and color of raw materials to reduce the workload of cleaning the crusher.

2. Make the rubber box bracket, reduce the time for the crusher to take the water outlet and reduce the labor intensity.

3. Use the automatic transmission belt crusher to reduce the workload of the crusher (one person can use two of the same crusher).

4. Isolate the area where the crusher is placed to avoid cross contamination. Strictly control the purity of the nozzle material, reduce the time for the crusher to clean the foreign matter in the nozzle material.

5. By improving mold quality, injection molding technology and management level, controlling defective products and water inlet material quantity, reducing the workload of crusher.

6. The mold adopts hot runner system to reduce the water inlet material and the amount of broken material.

7. The edge crusher is used to realize automatic and unmanned crushing.

8. When the crusher is out of service, cover with dust cover to reduce the workload of cleaning the crusher.

9. Train shatterers to improve their work quality, efficiency and responsibility, so as to reduce the number of shatterers.

7. Measures for injection molding machine operators to improve work efficiency and reduce manpower

1. Use manipulator and conveyor belt instead of hand to take out products and water orifice, realize automatic and unmanned operation production, reduce manual boot.

2. Must be prepared to injection mold cleaning, lubrication,  protection, prevent the thimble, slider, guide pin, guide sleeve, wear and tear, caused flash products. Do a good job of cleaning the rubber chips, rubber silk, oil and dust on the molding surface to reduce the rough edges around the products caused by the damage and pressing of the parting surface. Bartender  (mould)

3. Adopt in-mold shear gate technology or change the direct feeding mode to point gate to reduce the time of cutting water gate. (Mold design)

4. Improve the steel of the mold, improve the rigidity and hardness of the mold, and the mold should add the brace head, reduce the raw edge of the product caused by the mold compression deformation. Wear resistant steel is used for mold gate position, slider and moving parts and special treatment is carried out to reduce the burring caused by excessive wear of these parts. (Material of mold)

5. Do a good job of mold testing, thoroughly improve mold problems, improve mold quality, set technological conditions scientifically, and prevent products and water mouth from sticking mold phenomenon.

6. Optimize the layout of the machine in the injection molding workshop, so that one operator can simultaneously see the processing of two or more injection molding machine products. Improve the working efficiency of operators, to achieve workshop automation, unmanned operation production.

7. Do a good job in injection molding machine maintenance insurance  prevent machine hinge, elder brother Lin Zhu wear, clamping precision injection molded parts caused by poor raw edges. (Maintenance of machine)

8. Reduce mold locking force to prevent mold deformation caused by excessive mold locking force and rough edges. Scientific setting of opening and closing mold parameters, reduce the speed of opening and closing mold, reasonable setting of low pressure protection parameters, to prevent the rough edge caused by mold collision. (Setting of process)

9. Use appropriate tools for gate and raw edge processing, improve processing tools and techniques, improve processing efficiency and quality, and reduce machining manpower.

10. Make clear the processing parts, processing standards, processing requirements and processing methods of products, reduce unnecessary processing actions and shorten post-processing time. For the internal plastic parts, do not affect the function, size and assembly effect of the raw edge does not need to be processed, reduce the processing amount. And adhere to the principle of not allowing the production of flying edge mold.

11. Improve the salary of operators (slightly higher than the salary standard of peers), reduce the loss of operators, stabilize the staff team, the use of skilled workers boot (a skilled worker can be up to 2 skilled workers), is also one of the methods to reduce the airport manpower to improve the working efficiency of operators.

12. Strengthen job training for operators, improve their work quality, work efficiency and work responsibility, and mobilize the enthusiasm of employees.

Eight. IPQC measures to improve work efficiency and reduce manpower

1. Clear product quality standards (size, appearance, material, assembly, color…) And focus on the abnormal points of customer complaints and returns, and do a good job of the “first inspection record form” of products. Only after the first inspection is confirmed OK, can it be put into mass production.

2. Change the concept of “post-inspection”, strengthen the process control, for plastic parts prone to change parts (thimble, parting surface, pinhole…) And the time when quality is easy to change (meal time, shift time…) Focus on monitoring, try to stabilize the quality of injection parts, in order to reduce or eliminate IPQC personnel.

3. Establish the idea that “the quality of plastic products is from injection molding, not from seeing”, that is to say, “quality products are designed, manufactured, managed and controlled, rather than tested out”.

4. Implement scientific injection molding, gradually realize automatic and unmanned production mode, prevent quality fluctuations and adverse defects in the process of injection molding, so as to achieve the quality state of product quality without IPQC.

Ix. Measures for mold repair personnel to improve work efficiency and reduce manpower

1. To strengthen the use and maintenance of injection mold, the bartender  work, reduce the die failure rate, reduce the modulus. Strengthen the mold rust prevention work, reduce the occurrence of mold rust phenomenon.

2. Use appropriate mold steel (corrosion resistance, wear resistance, pressure resistance), and ensure that the mold has enough steel and hardness, prolong the service life of the mold.

3. The moving parts of the mold (vulnerable workpiece) are made into inserts, wear-resistant steel is used and quenched to facilitate quick maintenance and increase service life.

4. Reasonable setting of thimble times and thimble stroke (on the basis of the smooth release of the product, more than one top). And to do a good job of cleaning, lubricating, protecting  thimble, thimble way to avoid empty change traditional thimble mode, prevent burning needle, needle breakage phenomenon.

5. Enhance the protection consciousness of the mold, prohibit the phenomenon of “die pressing”, and reasonably set low-voltage protection parameters, and install “mold monitoring and protection device” if necessary for special molds.

6. The mold nozzle adopts the wire-drawing structure to prevent foreign bodies such as wire drawing and mold surface viscose chips and dust during the injection production process, which should be cleaned in time to avoid damaging the mold.

7. Install the thimble spring on all molds. If there is fracture, it should be replaced immediately to avoid the phenomenon of needle burning and broken caused by the imbalance of ejection.

8. There should be a certain amount of spare parts of the mould that are prone to loss and multiple failure parts, so that when the above parts of the mould fail, they can be replaced in time, so as to shorten the time of mould repair and reduce the manpower of mould repair.

9. Reduce the clamping force of injection molding machine (each machine should be controlled below 100) and the speed of unended closing mold to prevent mold deformation and collision.

10. Measures to improve work efficiency and reduce manpower for machine repair personnel

1. Change the idea for the maintenance of equipment is broke by the ex post maintenance into prevention concept. (preventive  bao and predictive  difference).

2. Make the injection molding machine use, maintenance, security  rules, and arrange the specialist injection molding machine and peripheral equipment

Injection molding machine for short injection molding machine.

Injection molding is the use of plastic thermophysical properties, the material from the hopper into the barrel, the barrel outside the heating ring heating, so that the material melt, in the barrel is equipped with external power motor drive rotating screw, material under the action of the screw, along the screw groove forward transportation and compaction, the material in the external heat and screw shear under the double action gradually plasticized, melting and homogenization, When the screw rotation, the material in the screw groove friction and shear force under the action, the molten material pushed to the head of the screw, at the same time, the screw in the material reaction backward, so that the head of the screw to form a storage space, complete the plasticization process, then, the screw in the injection cylinder piston thrust under the action, with high speed, high pressure, The molten material in the storage room is injected into the cavity of the mold through the nozzle. After the molten material in the cavity is kept under pressure, cooled and solidified, the mold is opened under the action of the mold closing mechanism, and the finished product is ejected from the mold through the ejecting device.

Two, the classification of injection molding machine

KII Series machine

There are three types of configuration according to the mold closing parts and injection parts: horizontal, vertical and Angle

(1) Horizontal injection molding machine: Horizontal injection molding machine is a very common type. It is characterized that the center line of the injection assembly is concentric or consistent with the center line of the closing assembly and parallel to the mounting ground. Its advantages are low center of gravity, stable work, mold installation, operation and maintenance are more convenient, mold open file, occupy space height is small; But covers a large area, large, medium and small machines are widely used.

(2) Vertical injection molding machine: its characteristic is that the axis of the closing device and the injection device is arranged in a line and perpendicular to the ground. It has the advantages of small floor area, convenient mold assembly and disassembly, easy installation of inserts, plasticizing of materials falling into the hopper more evenly, easy to realize automation and automatic line management of multiple machines. The disadvantage is that the ejecting product is not easy to fall off automatically, often need manual or other methods to take out, not easy to achieve full automatic operation and large product injection; High fuselage, feeding, maintenance inconvenience.

(3) Angle injection molding machine: the axes of the injection device and the mold device are arranged vertically. According to the relative position of the injection assembly center line and the installation base surface, there are horizontal, vertical and horizontal: (1) horizontal, injection assembly line and the base surface parallel, and the mold assembly center line and the base surface perpendicular; (2) Vertical horizontal, injection assembly center line is perpendicular to the base surface, and the mold assembly center line is parallel to the base surface. The Angle injection machine has the advantages of both horizontal and vertical injection machines. It is especially suitable for the mold with asymmetric geometric shape products with side sprue.

Three, injection molding machine structure analysis

Injection molding machine according to the injection molding process requirements is a mechanical and electrical integration of strong machine, mainly by injection parts, closing parts, fuselage, hydraulic system, heating system, control system, feeding device and so on. As shown in Figure 2.

Wechat photo _20190302110026

(1) Typical structure of injection molded parts

1. At present, the common injection device has single cylinder form and double cylinder form, our injection molding machine is double cylinder form, and are directly driven by hydraulic motor screw injection molding. Because of different manufacturers, different models of the machine its composition is not exactly the same, the following is a specific analysis of the machine used by our factory.

The composition of injection molding device of vertical machine and horizontal machine are shown in Figure 3 and Figure 4 respectively.

The working principle is: When preplasticizing, the screw in the plasticized part is driven by the hydraulic motor to rotate the main shaft, one end of the main shaft is connected with the screw key, and the other end is connected with the hydraulic motor key. When the screw rotates, the material is plasticized and the plasticized molten material is pushed to the storage chamber at the front end of the barrel. At the same time, the screw is backed up under the reaction of the material, and the thrust seat is backed up by the thrust bearing. Pull the piston rod straight back through the nut, complete the measurement, injection, the injection cylinder rod cavity oil through the bearing to push the piston rod to complete the action, the piston rod cavity oil to push the piston rod and screw to complete the injection action

Vertical injection molding machine has six systems: injection system, clamping system, hydraulic/hydraulic transmission system, electrical control system, heating/cooling system, lubrication system.
1: The jet system is one of the main features. There are three main forms: plunger type, screw type, and screw premolded plunger injection type. At present, screw type is the most widely used. Its role is in the cycle process of injection molding machine, in the specified time for a certain amount of plastic heating plasticizing, and then the molten plastic at a certain pressure and speed through the screw completely injected into the cavity.
2: clamping system is mainly composed of clamping device, adjusting mechanism, ejector mechanism, front and rear fixed template, moving template, clamping cylinder, safety protection mechanism seven parts. The closing system ensures that the mold is closed, opened and ejected. After the mold is closed, sufficient clamping force is provided to the mold to resist the pressure of the mold cavity caused by the molten plastic entering the mold cavity, so as to prevent the mold cracking and resulting in product defects.
3: Hydraulic system/hydraulic transmission system is mainly composed of various hydraulic components and hydraulic auxiliary components. Its power source is oil pump and motor. Control all kinds of hydraulic pressure and flow, can meet the requirements of various injection process. Its function is to provide power for various actions required by the injection molding machine process, to meet the pressure, speed and temperature of each part of the vertical injection molding machine and a series of requirements.
4: Electric control system of vertical injection molding machine by electronic control system and hydraulic system reasonable coordination, can realize the injection molding machine process requirements with pressure, temperature, speed, time and various procedures operation. It is mainly composed of electrical appliances, electronic components, meters, heaters, sensors and so on. Manual, semi-automatic, fully automatic and adjustment are four commonly used fuel injection control methods.
5: Heating/cooling system The heating system is mainly used to heat the cylinder and the nozzle. Generally, the electric heating coil is used as the heating device, which is installed outside the cylinder body, and the situation of the injection molding machine is detected by the thermocouple. The heat source of the material plasticized is formed through the heat conduction of the cylinder wall. The cooling system is mainly used to cool the oil temperature, which will cause a variety of failures, so the oil temperature must be controlled in time. The cooling position is close to the outlet of the feed pipe to prevent the raw material from melting at the outlet of the feed pipe, leading to the abnormal discharge and blockage of the raw material
6: The role of the lubrication system is to provide lubrication conditions for the motion template, adjusting device, connecting rod hinge and other relative moving parts of the vertical injection molding machine. Convenient to reduce energy consumption, improve parts life. Lubrication may be periodic manual lubrication or automatic electric lubrication.

Mobile phone shell is usually made of PC(polycarbonate) or PC+ABS material molding, due to the relatively poor liquidity of PC, so the process is usually filled with high mold temperature, high material temperature; The gate used is usually the point gate, and graded injection molding should be used when filling, to find the gate position and the V-P(injection – pressure maintaining) switching position, which will be of great help to solve the gate mark and underinjection fly-side and other anomalies.

The following is the main molding conditions of mobile phone products, introducing the melt temperature, mold temperature, injection speed, back pressure and other molding parameters setting points for attention.

Melting temperature and mold temperature

The optimal setting of molding temperature is related to many factors, such as injection molding machine size, screw configuration, mold and molding product design and molding cycle time. In general, to allow gradual melting of the plastic, lower temperatures are set at the back of the tube/feed area and higher temperatures at the front of the tube. However, if the screw is not designed properly or the L/D value is too small, the reverse temperature setting can also be used.

In terms of mold temperature, high temperature molds provide a better surface appearance, less residual stress, and are easier to fill for thinner or longer forms. And low die temperature can shorten the forming cycle.

Rotation speed of screw

40 to 70rpm is recommended, but it depends on the design of the machine and screw.

In order to fill the mold as quickly as possible, the injection pressure should be as high as possible, usually about 850 to 1,400kg/cm2 and up to 2,400kg/cm2.

Back pressure

Generally, the lower the better, but for uniform feed, it is recommended to use 3 to 14kg/cm2. Injection molding speed, rate of fire and gate design has a great relationship, the use of direct gate or edge gate, in order to prevent sunbeam phenomenon and wave flow mark phenomenon, the application of slower rate of fire. In addition, if the thickness of the finished product is more than 5MM, slow shooting helps to avoid bubbles or dents. Generally speaking, the principle of rate of fire is fast for thin and slow for thick.

Elimination of common defects

a. Air mark: reduce the flow rate of the melt overgate and increase the mold temperature.

b. Undernote: Improve injection pressure, speed, material temperature, mold temperature, improve the amount of glue.

c. Flying edge: reduce the plastic filling pressure, control the V-P switching point to prevent over-filling, improve the clamping force, and check the mold fit.

d. Deformation: Control mold temperature to prevent uneven shrinkage deformation caused by mold temperature difference, through pressure maintenance adjustment.

e. Weld mark: improve mold temperature, material temperature, control the flow of each section to prevent trapped gas, improve the flow front temperature, increase exhaust.

Secondary processing   

The post-processing of mobile phone shell usually includes spraying, color spraying, printing, sandwich printing, electroplating, vacuum evaporation, hot pressing nut, annealing, ultrasonic welding and so on.

By spraying, electroplating and other post-processing methods, the appearance of plastics can be improved, and the friction resistance of plastic surface can be improved. Hot pressing ultrasonic welding and other post-processing methods can add some inserts for easy assembly; Annealing treatment can eliminate the internal stress of products and improve the performance of products.

1.2 Application of injection molding machine
Injection molding processing method can be shaped complex shape, complex structure, high dimensional precision and plastic products with inlays. It has strong adaptability to the processing of various plastic materials, so it is widely used in household appliances, automobiles, aviation, instruments, national defense, telecommunications, medical treatment, construction and daily necessities and other industries, and has a wide range of uses.

1.3 Classification of injection molding machine
Injection molding machine is divided into plunger type, screw plunger type and reciprocating screw type injection molding machine according to plasticizing way, especially the past compound screw type is the most common; According to the transmission mode of the closing device can be divided into hydraulic, mechanical and hydraulic mechanical (connecting rod) type; According to the axis of the injection device and the axis of motion of the closing device, it can be divided into horizontal injection molding machine, vertical injection molding machine, Angle injection molding machine and multi-station injection molding machine, among which the horizontal injection molding machine is the most common.

(1) Classification of plasticizing methods

① Plunger injection molding machine

The characteristic is that the plasticizing parts are the barrel and the plunger. The plastic entering the barrel is heated by the barrel, and the injection molding process is promoted by the plunger. However, due to the lack of mixing of the melt in the cylinder, the temperature difference between the melt is great, and the temperature distribution of the melt is not uniform.

Figure 1. Structure diagram of plug injection molding machine

② Screw plunger injection molding machine

The plasticizing device of this injection molding machine is separated from the injection device. The parts that plasticize the rubber are the screw and the barrel, and the injection part is completed by the plunger. The rubber material is first uniformly plasticized in the plasticizer barrel by the screw, then enters the injection barrel by the check valve, and finally is pushed into the mold cavity by the plunger.

FIG. 2 Structure diagram of screw plug injection molding machine

plastic injection molding machine

Reciprocating screw injection molding machine

The plastic parts of the injection molding machine are the screw and the barrel. The rubber material entering the barrel is not only heated by the barrel, but also softened by the shear heat and friction heat generated by the rotation of the screw. The injection process is completed by a screw. In the plasticization process, due to the rotation of the screw, the plastic melt not only has axial movement, but also has lateral flow and cyclotron movement. These different forms of movement greatly promote the mixing effect of the plastic melt, so that the temperature in the melt reaches a high degree of uniformity. And the screw is one side of the rotation of plasticizing and backward measurement, its plasticizing capacity is large, plasticizing quality is good. So reciprocating screw injection molding machine is widely used.

FIG. 3 Structure diagram of reciprocating screw injection molding machine

(2) Classification by mold closing device

① All mechanical

Mechanical mold closing device refers to the mechanism action to the generation and maintenance of mold locking force are completed by mechanical transmission, also known as the full mechanical mold closing device. Early injection molding machines are all mechanical mold closing device injection molding machines, but because the adjustment of mold closing force and mold speed is more complex, inertia impact and noise, maintenance is difficult, there are few manufacturers.

② Full hydraulic type

Hydraulic clamping device refers to the production and maintenance of clamping action to clamping force are realized by hydraulic transmission system. Hydraulic mode closing device is safe, reliable, low noise, and can easily adjust the speed and force of mold closing. But there are hydraulic oil leakage and pressure fluctuation and the rigidity of the system is weak.

③ Hydraulic – mechanical type

Hydraulic-mechanical die closing device is composed of hydraulic system and mechanical elbow system, and has the advantages and disadvantages of both mechanical and hydraulic die closing devices. Currently it is the most commonly used model of thermoplastic injection molding machine.

④ Electric-mechanical type

The electric-mechanical mold closing device is composed of servo motor, winding gear belt, screw, bending elbow mechanism and so on. This type of closing device has no hydraulic pressure, can avoid oil leakage problems, and has the advantages of energy saving, low noise, clean, easy to operate and maintain. At present, most dust-free workshops use this kind of mold closing device.

(3) Classification by way of arrangement

① Horizontal injection molding machine

This is the most common type. The mold closing part and the injection part are on the same horizontal center line, and the mold is opened along the horizontal direction. Its characteristics are: the fuselage is low, easy to operate and maintain; Low center of gravity, stable installation; After ejecting products can use gravity to automatically fall, easy to realize automatic operation. At present, the injection molding machine on the market mostly uses this type.

② Vertical injection molding machine:

The mold closing part and the injection part are on the same vertical center line, and the mold is opened in a vertical direction. Therefore, its footprint is small, easy to place inserts, loading and unloading mold is more convenient, the material falling into the hopper can be plasticized more evenly. But the product is not easy to fall automatically after ejecting, must be taken off by hand, not easy to achieve automatic operation. Vertical injection molding machine is suitable for small injection molding machine, generally in 60 grams below the injection molding machine is used more, large and medium-sized machine should not be used.

Figure 4 Horizontal and vertical injection molding machine outline

③ Angle injection molding machine:

Its injection direction and die interface in the same surface, it is especially suitable for machining center parts do not allow gate traces of flat products. It covers an area smaller than the horizontal injection molding machine, but the insert into the mold is easy to tilt down. This type of injection molding machine is suitable for small machines.

Figure 5. Shape diagram of Angle injection molding machine

④ Multi-mold rotary disk injection molding machine:

It is a special injection molding machine with multi-station operation. Its characteristic is that the mold closing device adopts the rotating disk structure and the mold rotates around the rotating shaft. This type of injection molding machine gives full play to the plasticizing ability of the injection device, can shorten the production cycle, improve the production capacity of the machine, so it is especially suitable for the cooling setting time is long or because of the placement of inserts and need more auxiliary time for the production of mass products. But because of the large and complex system, the closing force of the closing device is often small, so this injection molding machine is widely used in the production of plastic soles and other products.

1.4 Structure and parameters of injection molding machine
Injection molding machine includes injection device, closing device, transmission system and electrical control system.

Figure 6. Outline of injection molding machine

Figure 7 Structure diagram of injection molding machine

The basic requirements of injection molding are plasticizing, injection and shaping. Plasticization is the premise to realize and guarantee the quality of the molding products, and in order to meet the requirements of molding, injection must ensure that there is enough pressure and speed. At the same time, due to the high injection pressure, the corresponding high pressure in the mold cavity (the average pressure in the mold cavity is generally between 20 and 45MPa), so there must be a large enough mold closing force. It can be seen that the injection device and the mold device are the key parts of the injection molding machine.

1.4.1 Injection system structure and parameters
1.4.1.1 Injection system structure and composition
The main components of the injection system include plasticizing injection device, screw drive device and measuring device. The following figure shows the main components of the screw reciprocating injection molding machine.

Figure 7 Main components of the injection system

(1) Plasticizing injection device

Mainly including screw, barrel (barrel) and heating element, in the head of the screw can also be arranged to prevent the reverse flow of melt or a variety of shear mixing head.

① Screw:

The injection screw has the function of plasticizing the plastic material and injecting the melt into the mold cavity. During plasticizing, the heating of the barrel and the rotation of the screw make the rubber material change from solid to viscous flow melt in the process of forward transportation; During injection, the screw moves forward to inject the melt at the front of the barrel into the mold cavity. The structure and working characteristics of screw have great influence on the production efficiency of injection molding machine and the quality of injection molding products.

The working characteristics of the screw: the screw moves axially in the plasticization and injection process; The work of the screw is interstitial, the plasticization process of the screw is unstable melting process, and the plasticization process is only the process of preparing the molten material for injection; After screw conveying and plasticizing, the rubber material still stays in the front section of the barrel for a period of time, and can still continue to accept the heating of the barrel and further plasticize.

Screw structure: In order to adapt to different properties of plastic processing requirements, the screw design for different structural forms. At present, the application of screw structure forms are: gradient type, mutation type and universal type.

Screw material: It is divided into full hard screw (SKD61, SKH-91 or HPT full hardening powder alloy steel), stainless steel screw (9Cr18Mov), double alloy screw (38CrMALA or SACM645 as the substrate), nitride screw (38CrMALA as the substrate), tungsten carbide screw (surface covered with cobalt and tungsten carbide composite alloy powder coating), plating Chrome screw, etc. The ordinary screw in our supplier is usually stainless steel screw or nitride screw; For fiber or V0 grade above the material, will generally use double alloy screw or tungsten carbide screw.

Screw classification is as follows:

Figure 7 Screw structure form

The graded screw is a screw with a long compression section (i.e., a melting section), characterized by a relatively gentle energy conversion during plasticization. As shown in FIG. 7 (a), the compression section L2 is long, and the depth of the screw groove in this section gradually becomes shallow from deep, and the energy conversion during plasticizing is relatively moderate. It is suitable for processing plastics with a wide melt temperature range, as such plastics require sufficient plasticizing process to melt completely. Gradient type screw is suitable for processing such as PS, PVC and other non-crystalline plastics with wide softening temperature range and high viscosity.
Mutant screw is a kind of screw with small compression section, which is characterized by intense energy conversion during plasticizing. As shown in FIG. 7 (b), the compression section L2 is short, and the depth of the screw groove in this section changes sharply from deep to shallow, and the energy conversion during plasticizing is relatively intense. Suitable for processing plastics with a narrow melt temperature range, because such plastics can be softened and melted in a short time as long as they have been preheated enough to reach the melting point. Mutant screw is suitable for processing polyamide and polyolefin crystalline plastics.
The compression length of the universal screw is between the gradient screw and the mutant screw. In order to avoid the production of different types of plastic materials to replace the screw, usually choose universal screw, at this time as long as the appropriate adjustment of the process parameters (such as cylinder temperature, screw speed and back pressure, etc.), can also meet the molding requirements of different plastic materials. As shown in Figure 7 (C), the length of compression section L2 is generally 4 to 5 pitch lengths. At the same time, it is suitable for the processing of both crystalline and non-crystalline plastics, considering not only the non-crystalline materials can not withstand the excessive shear plasticization of the mutant screw in the compression section, but also the technological characteristics of the crystalline materials that need enough preheating to soften and melt.
In order to avoid degradation of glue due to local overheating, it is necessary to cool and control the temperature of screw in production. At the beginning of injection molding machine manufacturing, most of the screw center hole into the flow of mineral oil for cooling; The heat pipe is now commonly used to cool the screw, which is characterized by the placement of a capillary suction core permeating the working liquid in the inner wall of the screw or the opening of a special oil tank. When the heat pipe works, the evaporation section of the heat pipe located in the metering section of the screw is heated, and the medium enclosed in it sublimates into steam and constantly flows back from the evaporation section to the condenser section of the heat pipe located in the plasticizing section of the screw is cooled to liquid. The liquid then flows to the evaporation section through the action of the capillary, forming a circulation. The medium in the heat pipe is water, oil and some organic solvents.

② Screw head

In the screw injection, for the rubber material with low viscosity, it is necessary to prevent the problems of low injection efficiency, large pressure loss and difficult pressure preservation caused by melt reflux. For the viscose material with higher viscosity, it is necessary to solve the problem of decomposition of hysteresis caused by incomplete discharge when injected, so the structure of the screw head has the form of check type screw head, prevent hysteresis decomposition type screw head and special purpose screw head.

FIG. 8 Reverse screw head

(3) Cylinder: the cylinder is generally a whole structure, there is a certain gap between the inner hole of the cylinder and the screw, and the external heating and cooling device is installed. Generally, 38CrMOALA surface nitriding is used, and tungsten carbide or HPT all-hardened powder alloy steel is used for fireproof V0 grade or fiber reinforced engineering plastics.

The number 1 represents PET, or polyethylene terephthalate

Mineral water bottles, carbonated drink bottles are made of this material. Dong Jinshi pointed out that hot water can not be recycled in beverage bottles. This material is heat-resistant to 70℃, which is only suitable for warm or frozen drinks. When loaded with high temperature liquid or heated, it is easy to deform and dissolve harmful substances to human body. Scientists found that after 10 months of use, the plastic could release carcinogens and become toxic to humans. So when you’re done, throw it away. Don’t use it as a water cup, or use it as a storage container for anything else. (The girl in the United Arab Emirates got cancer because she used the same mineral water bottle for 16 months, resulting in the release of carcinogen DEHP.)

The number 2 stands for HDPE, high density polyethylene

Plastic containers for cleaning supplies and bath products. At present, plastic bags used in supermarkets and shopping malls are mostly made of this material, which can withstand 110℃ high temperature. Plastic bags marked with food can be used to contain food. Plastic containers containing cleaning supplies and bath products can be reused after careful cleaning, but these containers are usually not easy to clean, residual original cleaning supplies, become a hotbed of bacteria, cleaning is not thorough, it is best not to recycle.

The number 3 represents PVC, or polyvinyl chloride

Common raincoat, building materials, plastic film, plastic box, etc. Good plasticity, cheap price. But can only withstand 81℃ high temperature. According to reports, this material of plastic products are easy to produce toxic and harmful substances from two aspects, one is the production process is not fully polymerized single molecule vinyl chloride, the second is harmful in plasticizer. These two substances in the encounter of high temperature and grease is easy to precipitate, poison with food into the human body, easy to cause cancer. Currently, containers of this material are used less often to package food. If in use, do not allow it to get hot.

The number 4 stands for LDPE, low density polyethylene

Plastic wrap, plastic film and so on are this material. Heat resistance is not strong, usually, qualified PE wrap in the temperature of more than 110℃ will appear hot melt phenomenon, will leave some plastic preparations that the human body can not decompose. In addition, wrap the food in plastic wrap and heat it. The fat in the food is easy to dissolve the harmful substances in the plastic wrap. Therefore, the food into the microwave oven, the first to remove the wrapping film.

The number 6 stands for PS, polystyrene

This is the material used to make instant noodles in bowls and foam fast food boxes. Heat-resistant and cold-resistant, but not in the microwave to avoid the release of chemicals due to excessive temperature. And can not be used to contain strong acids (such as orange juice), strong alkalinity.

PVC products with a plastic injection molding

PC is a material that is widely used, especially in the manufacture of baby bottles, space cups and so on. In recent years, baby bottles have become controversial because they contain BPA. Experts point out that, in theory, as long as in the process of making PC, bisphenol A 100% converted into plastic structure, it means that the product is completely free of bisphenol A, let alone release. However, if A small amount of BPA is not converted into the plastic structure of PC, it may be released into food or drink. The higher the temperature of the residual bisphenol A in PC, the more and faster the release rate. Therefore, hot water should not be served in PC water bottles. If the container has any fall or damage, it is recommended to stop using, because plastic products if there is a fine surface pit, easy to hide bacteria. Avoid repeated use of aging plastic appliances.

Check whether each lubrication part is fully lubricated; Check whether the oil pump has abnormal noise; Install and tighten the mold carefully, and pay attention to safety when loading and unloading the mold; Adjust pressure at all levels; Set all levels of temperature.

Manual operation and adjustment of vertical injection molding machine

Adjust the position of each switch manually to ensure the safety of the die. Set the manual button ON the electronic control panel to ON(open). When the machine is operated manually, each action button ON the electronic control operation panel can only be operated when the button is pressed (ON), and the action disappears when it is released. Mold adjustment:

First adjust the die close high voltage proximity switch travel block to the lowest point, then install the die in the center between the upper and lower die, and then press the die adjustment (pull out) button on the electronic control panel. At this point, the upper form begins to close the mold at low pressure and slow speed. After the die is sealed, adjust the close die close high pressure close pull stop block to a position that can raise the high pressure. At this point, the high pressure is turned off to increase the pressure when the manual die close button is pressed.

Close the vertical injection molding machine mold:

When semi-automatic, both hands hold down the two automatic start buttons on the operating table, then the machine closes the mold. At the beginning, the mold is closed quickly. When the closing mold is in contact with the lower closing mold entering switch block, the closing mold is closed slowly until the closing mold is completed. High voltage mode locking is produced when the high voltage proximity switch block is contacted.

Seat entry: used when mold alignment, that is, to control the forward use of the nozzle cylinder table.

Injection: According to the product material, shape and size, adjust the injection pressure, maintain the pressure and cure the injection time and position, then press the injection button to complete the injection. (Note: When the temperature reaches the set value, the shooting action can be performed).

Screw feeding: After pressing the feed button, the screw rotates the rubber, and the stirring compression screw rises (the rising speed is determined by the adjustment of the back pressure regulating valve). When the rising action of the screw contacts the feed contact switch block, the feeding action stops. The size of the feeding stroke depends on the amount of feeding required by the product.

Loose: When manually pressing the loose button, the screw moves upward, and the shooting action can be performed.

Before starting

1. Before the operation of the injection molding machine, check whether there is water and oil in the electrical control box. If the electrical equipment is damp, do not start the machine. There should be maintenance personnel to blow dry electrical parts before starting.

2. Before the operation of injection molding machine, check whether the supply voltage is in line with it. Generally, it should not exceed ±6%.

3. Check whether the emergency stop switch and front and rear safety door switches are normal. Verify the motor and oil pump rotation direction is consistent.

4. Check whether the cooling pipes are unimpeded for long distance, and pass cooling water into the cooling water jacket of the oil cooler and the end of the barrel.

5. Before operation of injection molding machine, check whether there is lubricating oil in each moving part, and add enough lubricating oil.

6. Turn on the electric heat and heat each section of the cylinder. When the temperature of each section reaches the requirements, heat preservation for a period of time to make the temperature of the machine stable. The holding time varies according to the requirements of different equipment and plastic raw materials.

7. Add enough plastic to the hopper. According to the requirements of injection molding different plastics, some raw materials are best after drying.

8. Cover the heat shield on the barrel, which can save electricity and prolong the life of the electric heating ring and current contactor

1. Do not cancel the role of the safety door for convenience.

2. Pay attention to the temperature of the pressure oil, and the oil temperature should not exceed the prescribed range. The ideal working temperature of hydraulic oil should be kept between 45-50℃, generally in the range of 35-60℃ is more appropriate

3. Pay attention to adjust the switch of each stroke to avoid the impact of the machine during operation.

Due to the structure and variety of injection products, so used for molding injection products injection machine types are more.

1. Classify raw materials according to plasticizing and injection methods.

2. Classification according to the shape and structure of the injection machine.

3. Classification according to the processing capacity of injection molding machine.

4. Classification by special purpose of injection machine.

plastic injection molding machine

According to the classification of plasticizing and injection of raw materials, the injection molding machine can be divided into three kinds: (1) plunger type, (2) reciprocating screw type and (3) screw plasticizing plunger injection type.

According to the different shape and structure of the injection machine, it can be divided into (1) vertical injection molding machine, (2) horizontal injection machine, (3) Angle injection machine, (4) multi-mold injection machine, (5) combined injection machine

According to the size of the processing capacity of the injection machine classification, can be divided into (1) ultra-small injection machine, (2) small injection molding machine, (3) medium injection molding machine, (4) large injection machine (5) ultra-large injection molding machine

• Plastic Products Mould Making Machine

According to the purpose of the injection machine can be divided into (1) general injection machine, (2) exhaust injection machine, (3) precision high-speed injection machine, (4) plastic shoe injection machine, (5) three injection head single-mode injection machine, (6) double injection head two-mode injection machine

2. Comprehensive performance parameters of injection molding machine
The design and manufacture of injection molding machine is a more reasonable economic index, is to assess some of its comprehensive performance parameters, is to meet the production of qualified injection molding mouth outside the parameters, that is, the number of injection time and space cycles, total power of electricity, total quality of equipment and equipment dimensions.

The empty cycle time is composed of the switching time other than the mold closing time, the injection seat moving back and forth, the mold opening time, the plasticizing time, the injection time, the pressure retaining time, the cooling time and the taking out of the workpiece. It is also the idle time in the completion of a cycle of the product.

Empty cycle time is also an index to measure the production capacity of the injection machine, which reflects the quality of the mechanical structure, the sensitivity of the operation, the hydraulic system and the working quality of the electrical performance parameters.

In order to meet people’s large demand for injection products, to meet the market supply, DKM plastic industry engineers and technicians through continuous efforts, gradually to the injection product production of high-speed, automatic direction. The following measures are very good to improve the injection molding machine, quality sublimation.

1. Increase the number of cycles of injection molding machine per unit time: by improving the screw speed for plasticizing materials, accelerate the injection speed of molten material, in order to shorten the production cycle of single product injection molding, so as to achieve the effect of increasing the number of cycles.

2. One injection machine is equipped with two injection cylinders. The preplastic screw can feed the two injection cylinders successively to achieve continuous injection.

3. Use two sets of mold injection molding. When working, the two sets of molds rotate and transpose, so that the melting injection, cooling and mold opening processes are carried out at two stations at the same time, which shortens the waiting time of pre-plastic stop and nearly doubles the production capacity of the injection machine.

4. Realize automation: in the production process of injection molding products, the computer is used to control the delivery of raw materials, cylinder feeding, process temperature control, mold opening, parts taking out and other processes to implement automatic program control.

5. In order to make injection molding products can work in a variety of special environments, it is required to use different properties of plastics to produce plastic products that can adapt to a variety of working environments. Different properties of plastic products, its injection production process conditions are different, which promotes the injection machine to special development. Such as with good electrical properties, physical properties and heat resistance, not easy to deform products production with thermosetting plastic injection molding machine, a variety of colors, a variety of raw materials composite molding with multi-color injection machine, designed to improve product quality of the exhaust injection machine, fiber reinforced plastic injection machine, low foaming injection machine and injection blow molding machine.

6. In terms of injection molding production process, some have adopted flow injection molding, injection compression molding, sandwich injection molding, reaction injection molding and gas assisted injection molding, etc.

3 Advantages of high speed injection molding machine

1. Hydraulic system – High energy saving

2. Hydraulic system – rate

3. Electric control part – high precision

4. Mold closing system – high rigidity

5. Injection System – High response

6. Injection System – High plasticizing

7. High security

1. Stability, reliability, safety and service life of the machine. This is the most important factor to consider when purchasing injection molding machine. Because every consumer does not buy a product to solve a temporary need, but to use it for a long time. Therefore, the performance of the product itself is very important.

2. Technical parameters are also very important. No matter what kind of product we buy, we know its various performance through the relevant parameters. And consumers in the purchase of injection molding machine, the manufacturer can provide the relevant technical parameters of the same industry standards or domestic and foreign similar injection molding machine technical parameters compared, the larger gap belongs to defective products. In the process of comparison, careful comparison is needed to avoid omissions.

3. Machine maintenance and overhaul should be convenient. Maintenance can also be a factor when choosing a product. General products in the use of the process will appear some problems, then fast and convenient maintenance is very key.

4. The last but not the least point is the choice of suppliers. In general, consumers are willing to buy products from local manufacturers with service offices. Because the structure of injection molding machine is more complex, problems will inevitably occur in the process of use. At this time, the after-sales service of the product is very key, and this factor must be considered when choosing. And in general, injection molding machine manufacturers will directly choose direct sales, so that the price will be more affordable

screw cylinder

There are the following points for attention in the maintenance of screw tube of injection molding machine:

• Do not start the machine when the barrel does not reach the preset temperature. The new electric heating is generally required to reach the set temperature 30 minutes before operating the screw.
• If the machine stops for more than half an hour each time, it is best to close the blanking port and shoot clean the material in the cylinder, and set the insulation
• Avoid foreign matter falling into the barrel and damaging the screw and barrel. Prevent metal debris and debris from falling into the hopper. If the recycled material is processed, magnetic hopper should be added to prevent iron filings from entering the barrel.
• The use of anti-salivating to ensure that the plastic in the cylinder is completely melted, so as not to damage the transmission system parts when the screw backward.

Spiral tube

• Avoid screw idling, skid and other phenomena.
• When using new plastic, the remaining material of the cylinder should be cleaned. When using POM, PVC, PA+GF and other materials, try to reduce the degradation of raw materials, and rinse with PP materials in time after shutdown.
• Avoid mixing POM and PVC into the barrel at the same time, which will cause serious industrial accidents at the melting temperature.
• Found molten plastic abnormal or discoloration, brittle products, should adjust the temperature to confirm the heating ring temperature line work is normal, check whether the screw and over the glue head assembly is damaged.
• Such as disassembly or replacement of the nozzle, screw head, flange, to the surface of the bolt thread coated with high temperature anti-corrosion paste, in order to facilitate future disassembly.

• Plastic Products Mould Making Machine

The general molding process of screw injection molding machine is: Firstly, granular or powdery plastic is added into the cylinder, and the plastic becomes molten by rotating the screw and heating the outer wall of the cylinder. Then, the machine moves the mold closing and injection seat forward, so that the nozzle is close to the gate of the mold. Then, pressure oil is injected into the injection cylinder, so that the screw is pushed forward, so that the molten material is injected into the closed mold with low temperature at a high pressure and fast speed. After a certain amount of time and pressure holding (also known as pressure holding), cooling, so that it solidifies, the mold can be opened to take out the product (the purpose of pressure holding is to prevent the reverse flow of the molten material in the mold cavity, to replenish the material in the mold cavity, and to ensure that the product has a certain density and dimensional tolerance). The basic requirements of injection molding are plasticizing, injection and molding. Plasticization is the premise to realize and guarantee the quality of the molding products, and in order to meet the molding requirements, the injection must ensure that there is enough pressure and speed. At the same time, due to the high injection pressure, the corresponding high pressure in the mold cavity (the average pressure in the mold cavity is generally between 20 and 45MPa), so there is a large enough mold closing force. It can be seen that the injection device and the mold device are the key parts of the injection molding machine.
The evaluation of plastic products mainly has three aspects, one is the appearance quality, including integrity, color, luster and so on; Second, the accuracy between size and relative position; The third is corresponding to the use of physical properties, chemical properties, electrical properties, etc. These quality requirements are based on the use of products in different occasions, the scale of the requirements are also different. The defects of the products mainly lie in the design, manufacturing accuracy and wear degree of the die. But in fact, the technicians of plastic processing plants often suffer from the difficult situation of using technological means to make up for the problems caused by mold defects and little effect.

The adjustment of technology in the production process is a necessary way to improve product quality and yield. Because the injection cycle itself is very short, if the process conditions are not good, the waste will flow. When adjusting the process, it is best to change one condition at a time and observe several times. If the pressure, temperature and time are all adjusted together, it is easy to cause confusion and misunderstanding, and the problem does not know what the reason is. There are many measures and means to adjust the process. For example, there are more than ten possible solutions to solve the problem of product dissatisfaction. Only by choosing one or two major solutions to solve the crux of the problem can we really solve the problem. In addition, attention should be paid to the dialectical relationship in the solution. For example: products appear sag, sometimes to improve the material temperature, sometimes to reduce the material temperature; Sometimes you have to increase the amount of material, sometimes you have to reduce the amount of material. Acknowledge the feasibility of reverse measures to solve the problem.

KII Series machine

It is the thermoplastic or thermosetting material using plastic molding mold to make plastic products of various shapes of the main molding equipment.
Divided into vertica

l, horizontal, full electric. The injection molding machine heats the plastic and applies high pressure to the molten plastic, causing it to shoot out and fill the mold cavity.

History of injection molding machine.

The injection molding machine was invented in the United States in 1872 and has a history of 130 years, but the screw injection molding machine has been developed in the past 50 years and become the most commonly used injection molding machine in the industry today.

At present in the engineering plastics industry, 80% of the use of injection molding.
The common horizontal injection molding machine is still.

Development prospect of injection molding machine.

• High speed: Requires the production cycle to be as fast as possible.
• High efficiency and energy saving: In terms of energy consumption, we should save electricity.
• Environmental protection: Existing hydraulic injection molding machine, there are oil pollution problems.
• Large injection molding machine development direction: Two plate machine.
• Small injection molding machine development direction: All electric, electro – hydraulic compliance.

Now is the new historical period of innovation and development of the plastic processing industry. The main development tasks of the industry are to optimize the structure, change the development mode, promote industrial upgrading, and highlight the transformation from large to strong, from fast to good. Injection molding industry is facing the challenge of transforming from traditional injection molding to intelligent injection molding.

Usually, injection molding machines will have the problem of high electricity consumption, and because of what reasons? For the traditional injection molding machine, how to expand the space of energy saving?

How to reduce the power consumption of injection molding machine?

The energy consumption of the machine is mainly reflected in the following parts:

(1) Electric energy consumption of hydraulic system oil pump; (2) The power consumption of the heater; (3) Power consumption of circulating cooling water pump. The power consumption of hydraulic oil pump accounts for more than 80% of the total power consumption of injection molding machine.

Parameter of machine

         So, what are the energy-saving transformation methods of injection molding machine?

         (1) Use injection molding machine power saving system

The power saving system independently developed by Zhongke Yujie adopts closed-loop control, detects the pressure and flow signal of the injection molding machine through the sensor, and automatically adjusts the motor speed of the oil pump, so that the oil supply is consistent with the demand of the injection molding machine (i.e. reduces the output power), so as to achieve the purpose of energy saving.

         (2) Nano energy-saving heating ring of injection molding machine

For the injection molding machine barrel heating energy saving, using infrared radiation conduction mode, nano infrared energy-saving electric heating ring installed on the outside of the heating object, so that heat conduction one-way, effective conduction to the heating body, and small thermal inertia, high temperature control precision; The thermal efficiency is more than 99.8%, and the electricity saving can reach more than 30%.

         (3) Energy-saving insulation sleeve for injection molding machine

For injection machine barrel insulation energy saving, reduce heat loss and energy saving, covering plastic extrusion, injection molding and surface temperature, reduce heat loss, to save energy, thus saving production electricity and air conditioning electricity.

Injection molding machine in the mold closing, locking, shooting glue, cooling, pressure holding, mold opening and other stages of the required pressure and flow are changed. When the oil demand of injection molding machine changes, by the relief valve located in the oil pump outlet to adjust the load pressure and flow, and the output power of the motor is unchanged, resulting in energy waste.