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The ultimate guide to daily maintenance of injection molding machines

TIME:2021-03-16 Share

Lisong Machinery is an injection molding machine production base integrating R&D, production, sales and service. The company has a senior design team that analyzes and optimizes the mechanism and operation control of the injection molding machine through finite element and kinematic simulation technology. , To ensure the reliability and life of the machine, to provide customers with perfect product solutions. The following is the daily maintenance and repair guide for injection molding machines summarized by our company:

1. Causes and prevention of failures of the plastic machine

Causes of failure of the clamping structure and prevention of hinged edge fracture:
A. Excessive clamping force
Generally, the maximum pressure of the injection molding machine system is 140bar, and the maximum stress of the hinge is also calculated based on 140bar. Under normal operating conditions, the hinged edge will have a life span of several years. If the system pressure is increased by more than 140bar, the stress on the hinged edge will exceed the safe range and cause damage to the hinged edge.
B. Poor operation
When the injection molding machine is working normally, the mold needs sufficient clamping force to withstand the strong pressure generated by the injection. This will prevent flashing or defects in the product. If the clamping force is not adjusted properly or the mold is installed improperly, the product will have flashing. This situation will not only affect the product quality, but also cause damage to the hinged edge. The reason is that the flashing will increase the stretched length of the Corinth column. At the same time, the stress on the hinged edge increases accordingly. Long-term flashing causes damage to the hinge.
C. Insufficient lubrication
Machine hinges need to be replenished with lubricating oil every day to reduce the friction between the hinges and the hinges and maintain the hinges to work normally. If the lubricating oil is not refilled in time, the hinged edge will be easily burned and broken due to increased friction. In addition, if the lubricating oil is replenished regularly, the effect may not be obtained. The reason may be that the hinge is shifted and the lubricating oil hole is blocked; or the oil pit of the hinge is dirty and blocked, causing the lubricating oil to be unable to be refilled normally and lose Lubrication. Eventually make the hinged edge cause injury. It is also necessary to choose the right lubricating oil correctly, because the oil that is too thin is easy to lose, but the fluidity of the oil that is too thick is also insufficient.
D. Poor design
If the injection molded parts are unevenly distributed in the mold, it can cause flashing of the product and increase the extension of the Corinth column, causing damage to the hinge.

PET Special Injection Machine
Failure prevention:
A. The mold pressure is too high. The system pressure should be maintained at 140 bar and cannot be increased by itself. Some customers often misunderstand that the clamping pressure is insufficient. The reason is that when the pressure of the pressure gauge shows about 110bar when the high-pressure clamping, they mistakenly believe that the pressure is insufficient and increase the system pressure by more than 140bar. Its real-time clamping force has reached the highest standard. At present, the general pressure gauge has a simple structure and cannot respond to rapid pressure changes in time. That is, when high-pressure clamping, the high-pressure pressure rises and drops rapidly, so the highest lock is adjusted When the mold force is used, the pressure gauge can only display a pressure of about 110 bar.

B. Poor operation
1. When using an injection molding machine, you should first consider installing a suitable mold. The clamping force required by the product cannot exceed the standard specifications of the injection molding machine. The calculation of the clamping force can refer to the relevant calculation methods.
2. When adjusting the injection molding parameters, avoid that the injection pressure is greater than the clamping force, the material temperature or mold temperature is too high, and the injection speed is too fast. In addition, whether the parallelism and rigidity of the mold meet the standards, and whether the mold is installed Squeeze.

C. Insufficient lubrication
Arrange employees to replenish lubricating oil on the hinges regularly. In addition, check whether there is enough lubricating oil in the lubrication pipes and hinges from time to time. The oil distributor should be adjusted as far as possible to not cooperate with the hinge to supply oil. If dirt such as oil holes are found, clean them up in time. If you find that the hinge is often short of oil and the lubricating oil supply is normal, you should check whether the through hole on the hinge (steel sleeve) position is moving.

Corinth pillar breaks:
A. The reason for the fracture of the forest column is basically the same as that of the hinged edge. In the clamping structure, the hinge of the Collin column withstands strong injection pressure during injection molding. According to the calculation of the design formula, the Collin column and the hinged edge are in compliance with the standard. Therefore, under normal operating conditions, the life span of the Collin column and hinge can be guaranteed. However, if there is a problem with the operation and the clamping pressure is increased beyond the safe range, the Corinthian column will be injured and the life will be reduced.
B. Some external reasons may cause the collimator column to break: the geometric tolerance of the template exceeds the standard. If the parallelism and verticality of the template exceed the standard, the force distribution of the clamping structure will be affected. Therefore, the four collimator columns have to bear different tensions. , Shorten the life span.

The reasons that cause the parallelism or perpendicularity to exceed the standard can be divided into the following aspects:
1. The parallelism or perpendicularity of the mold used exceeds the standard;
2. The screws used to tighten the clamping structure are loosened and the structure is deformed;
3. The parts are not properly installed after maintenance, so that the tolerance exceeds the standard;
4. After repairing the mold adjustment structure, the installation is not proper, and the individual mold adjustment nut is too loose or too tight.

Failure prevention:
A. Maintain the system pressure at 140bar, and it cannot be increased by itself. Pay attention to the operating conditions to avoid flashing of the product and select the appropriate mold.
B. The geometric tolerance of the template exceeds the standard. Regular inspections should be carried out. If the tolerance is found to exceed the standard, it should be corrected immediately. The screws in the clamping structure should be tightened. If they are loosened, they should be tightened immediately to prevent the clamping structure from being affected.

Maintenance of the clamping part:
1. Check whether the central lubrication system and its oil distributor and lubricating oil hose are working properly every day, and they are clean.
2. Keep the slide rail of the mobile template clean and lubricated
3. Avoid using close to or exceeding the system pressure clamping
4. Control the position of the mold opening and clamping action at the most appropriate position, so that the mold opening action is smooth and the impact is reduced.
5. Avoid using too large and heavy molds.

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