How to conduct annual maintenance of hot runner plastic molds?

- Mar 13, 2018-

1. Look for rust or dampness at the diffuser hole          If rust or moisture is found near the hot runner vent, internal condensation or water pipes may be broken. Moisture causes a fatal short circuit in the heater and the heater is damaged. If the hot runner mold is turned off at night or on weekends, it will not stop running for the whole year, and the chance of this condensation will be much greater.2. Be careful not to clean the nozzle tip at the gate.

         There is a small piece of stainless steel at the nozzle of the mold. It may be a point nozzle assembly. If you clear this seemingly obstructing thing, it will often ruin the hot head. In order not to damage the hot nozzle, confirm the nozzle type of the hot runner system before taking any action to ensure that all operators are trained and able to recognize all the different types of hot nozzles they contact.

3. Sliding buckle 

           For machines that do not run for the whole year, this work is best done once a week. (Maybe some companies can't do it.) The end of the year is a very good time. These parts must undergo a routine lubrication maintenance. 

4. Measure the resistance of the correction heater 

            If you have already measured the resistance of the heater when you first started using it, it is time to measure it again and compare it. The resistance value has a fluctuation of 10% above and below. Consider replacing the heater to ensure that it does not come out at a critical moment in the production process. If you have never measured the initial resistance value, measure it now and use the resulting value as reference data for future inspections of the heater.

5. Look for signs of wear between guide posts and guide bushes             Look for signs of scratches or scratches that are due to lack of lubrication. If the mark is only present, the life of the guide post and guide bush can be extended by adding more lubrication. If the wear is severe, replace the new part. Otherwise, the cavity and the core part may not be well matched, resulting in a thin and thick part wall.6. Check the water transfer situation            Connect a hose at the outlet of the waterway and let the water stay in the bucket through the water pipe. If the outflow of water is not clear or colored, there may be rusting, and the lack of smoothness means that it is blocked somewhere. If you find any of these problems, drill all the water pipes again and ensure that they are clear (or use any method you use most often for cleaning). Improvements to the plant's water treatment system can prevent future problems caused by rust and blockages.

7. Cleaning thimble           After a year, the ejector pin gets very dirty due to gas accumulation and filmy impurities. It is recommended to clean it with a mold cleaner every six to twelve months. After cleaning, apply a layer of lubricant to the thimble to prevent galling or breaking.8. Check if there is a gap in the radius of the hot nozzle          Fracture is caused by the holding force of the loose, hardened plastic scrap that remains in the hot nozzle of the machine from the injection barrel assembly during forward injection molding. The cause of the problem may also be misalignment of the centerline. Consider these two possibilities when you find a fracture.             If you suffer the damage was severe enough not to prevent petal-like leakage (a term formerly used by mold users: refer to the plastic leakage that occurred between the guide sleeve and the hot mouthpiece of the machine) and should replace the sprue bushing. The above suggestions will help you discover and prevent potential problems and ensure that your mold will always operate at its best.