Problems Easily Neglected in the Maintenance of Injection Mold

The maintenance procedure required for each injection molding position depends on the different mold cycle.

Here are some general principles that each mold user can use to ensure the effective operation of mold components such as hot runner, heater, guide post and thimble, so as to prevent accidents.

1. Check whether there is early-warning rust or moisture at the blowhole.

If you find rust or moisture near the hot runner vent, it means internal condensation or possible water pipe rupture.

Moisture can cause a fatal short circuit to the heater.

If the machine does not run all year round, but shuts down at night or on weekends, the probability of this condensation will increase.

2. Remember to remind the operator not to “clean” the hot nozzle at the gate.

If the operator happens to see a small piece of stainless steel at the nozzle of the die, it may actually be a point nozzle assembly.

“Cleaning up” what seems to be an obstacle often destroys the hot mouth.

In order not to damage the hot nozzle, please confirm the nozzle type of the lower hot runner system before taking action to ensure that all operators are well-trained and can identify all the different types of nozzles they contact.

3. Sliding buckle

For machines that operate continuously throughout the year, this work should be carried out once a week.

4. Check the resistance value of heater interactively

You should have measured the resistance of the heater when you first started using it.

Now it’s time to measure and compare it again.

If the resistance value fluctuates by 10%, consider replacing the heater to ensure that it will not go wrong at a critical time in the production process.

If you have never measured the initial resistance value, measure it now and use the obtained value as the reference data when checking the heater in the future.

5. Check whether there are signs of wear between guide post and guide sleeve.

Look for scratches.

This wear is due to lack of lubrication.

If the marks are just emerging, you can also extend the service life of the guide post and guide sleeve by adding more lubrication.

If the wear is serious, it’s time to replace the parts with new ones.

Otherwise, the cavity and core may not fit well, resulting in different thickness of the cavity wall of the parts.

6. Check the water flow

Connect a hose at the outlet of the waterway and let the water stay in the bucket through the hose.

If the water flowing out is not clear or colored, rust may occur, and the poor flow means that there is a blockage somewhere.

If these problems are found, drill through all water pipes again to ensure that they are unblocked (or clean them by any method you use most often).

Improving the plant’s water treatment system can prevent problems caused by rust and blockage in the future.

7. Clean the ejector pin

After a year, the thimble will become very dirty due to gas accumulation and membrane impurities.

It is recommended to clean the mold with mold cleaner every six to twelve months.

After cleaning, apply a layer of lubricant on the thimble to prevent scratch or fracture.

8. Check whether there is fracture in the radius area of the hot nozzle

The fracture is caused by the clamping force brought by the loose and hardened plastic fragments left in the hot mouth of the machine from the injection barrel assembly during forward injection molding.

The cause of the problem may also be the misalignment of the centerline.

These two possibilities should be considered when finding fracture.

If the damage is so severe that petal leakage cannot be prevented (a term previously used by the mold user: Plastic leakage between the guide sleeve and the hot nozzle of the machine), the gate sleeve should be replaced.