15 Great Recommendations for Injection Mold Use and Maintenance

Everyone knows that a good mold can be more expensive than the injection molding machine itself. Compared with other molds, injection molds are more complex and precise in structure, and require higher operation and maintenance. Therefore, in the entire injection molding production process, correct use and careful maintenance are important for maintaining the normal production and maintenance of injection molding companies as well as improving corporate efficiency.

The following are suggestions for the daily use and maintenance of injection molds.

1. Choose the appropriate molding equipment and determine reasonable process conditions

If the injection molding machine is too small, it will not meet the requirements. If too large, it will be a waste of energy. Besides, it will also damage the mold or template due to inappropriate adjustment of the clamping force, making the efficiency reduce.

When selecting the injection molding machine, it should be based on the following points:

  • maximum injection volume
  • effective distance of the tie rod
  • mold installation size on the template
  • maximum mold thickness
  • minimum mold thickness
  • template stroke
  • ejection method
  • ejection stroke
  • injection pressure
  • mold clamping force, etc.
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Check and use it after meeting the requirements. The process conditions is also one of the contents of the correct use of the mold. Too much clamping force, too high injection pressure, too fast injection rate, and too high mold temperature will damage the service life of the mold.

2. Check the operation of the empty mold

After the mold is installed on the injection machine, the empty mold must be run first. Observe the following points:

  • whether the movement of each part is flexible
  • whether there is any abnormal phenomenon
  • whether the ejection stroke and opening stroke are in place
  • whether the parting surface is tightly matched when the mold is closed
  • whether the pressure plate screw is tightened.

3. Maintain the mold at a normal temperature.

When the mold is in use, it is necessary to maintain the normal temperature. Working at the normal temperature can prolong the service life of the mold.

4. Regularly check the sliding parts on the mold

The sliding parts on the mold, such as guide posts, back pins, push rods, cores, etc., should be observed at any time. What’s more, they should be checked regularly, scrubbed and filled with lubricating grease at the right time, especially in the summer when the temperature is high. Add oil at least twice per shift to ensure that these sliding parts move flexibly and prevent tightness.

5. Make sure the cavity is clean

Before each mold clamping, you should pay attention to whether the cavity is cleaned. And no residual products or any other foreign objects are allowed to remain. It is strictly forbidden to use hard tools during cleaning to prevent damage to the surface of the cavity.

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6. Control the surface roughness at a right point. 

Molds with special requirements on the surface of the cavity, the surface roughness Ra is less than or equal to 0.2cm. It absolutely can not be wiped by hand or cotton silk. We can use compressed air to blow, or use high-grade napkins and high-grade absorbent cotton dipped in alcohol to gently wipe wipe.

7. The surface of the cavity should be cleaned regularly.

During the molding process of the injection mold, low-molecular compounds will often decompose to corrode the mold cavity. And that makes the bright cavity surface gradually become dull and degrading the quality of the product. So it needs to be scrubbed regularly. We can use alcohol or ketone preparations and then blow dry in time.

8. Do the anti-rust treatment for cavity and keep the mold clean.

When requiring a temporary shutdown, the mold should be closed to prevent the cavity and core from being exposed to prevent accidental damage. The shutdown time is expected to exceed 24 hours. And the surface of the cavity and core should be sprayed with anti-rust oil or release agent, especially in humid areas and rainy seasons. Even if the time is short, anti-rust treatment should be done.

The water vapor in the air will reduce the surface quality of the mold cavity and the surface quality of the product. When the mold is used again, the oil on the mold should be removed and wiped clean before use. The cleaning compressed air required for the mirror surface is blown dry and then dried with hot air. Otherwise it will ooze out during molding and cause defects in the product.

9. Check before restarting the machine

Turn on the machine after a temporary shutdown. After opening the mold, check whether the slider limit is moving. Only when no abnormality is found can the mold be closed. In short, you must be cautious and not careless before starting the machine.

10. Do something to prolong the service life of the cooling water channel

When the mold is out of service, compressed air should be used to immediately remove the water in the cooling water channel. Then, put a small amount of oil into the mouth of the nozzle. Next, blow with compressed air to make all cooling pipes covered with a layer of anti-rust oil.

11. Carefully check the working status of each control component during work

So that it can prevent abnormalities in the auxiliary system, maintenance of the heating and control system are particularly important for hot runner molds. After the end of each production cycle, the rod heaters, band heaters, and thermocouples should be measured with ohmic mothers. Besides, it should be compared with the technical specifications of the mold to ensure that their functions are intact. At the same time, the control loop may pass the test of the ammeter installed in the loop. The oil in the hydraulic cylinder used for core pulling is emptied as much as possible. While the oil nozzle is sealed to prevent the hydraulic oil from leaking or polluting the surrounding environment during storage and transportation.

12. Inspect the operating molds

If you hear abnormal noise from the mold or other abnormal conditions during production, you should stop the machine immediately for inspection. The mold maintenance personnel shall conduct patrolling inspections of the molds in the workshop that are operating normally. If any abnormalities are found, they shall be dealt with in time.

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13. Manage the handovers well and keep detailed working log

When the operator is handing over shifts, in addition to handing over production and process critical records, he also needs to have a detailed account of the mold usage status.

14. Record the mold information in detail

When the mold has completed the production quantity and needs to be removed from the machine to replace other molds, the mold cavity should be coated with anti-rust agent. Then, send the mold and its accessories to the mold maintenance staff, and attach the last qualified product as a sample. In addition, a list of mold usage should be submitted to fill in the details. The details include:

  • which machine tool the mold is on
  • how many products have been produced from a certain year, a certain month, and a certain day
  • whether the current mold is in good condition.

If there is a problem with the mold, fill in the mold on the use sheet, propose specific requirements for modification and improvement, and submit an unprocessed sample to the custodian for reference when repairing the mold.

15. A mold library should be set upwith some dedicated people for management and some mold files

If possible, computer management of the mold should be implemented. The mold warehouse should choose a place with low humidity and ventilation with temperature kept below 70%. If the humidity exceeds 70%, the mold is easy to rust. The mold should be stored on the shelf, and pay attention to anti-corrosion and dust-proof. It must be marked with signs that require repair or completion of repairs and maintenance.

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