The maintenance procedures required for each injection molding position depend on the different mold cycle periods. The following are some general principles that every mold user can use to ensure the effective operation of mold components such as hot runners, heaters, guide pins and ejector pins to prevent unexpected situations.
1, Check the vents for warning signs of rust or moisture. If you see rust or moisture near the hot runner exhaust vents, it could indicate internal condensation or a broken pipe. Moisture can cause a short circuit, potentially fatal to the heater. The likelihood of condensation is increased if the machine is not running 24/7 but is shut down at night or on weekends.
2, Remember to remind operators not to “clean” the nozzle tip at the gate – If an operator happens to see a small piece of stainless steel at the mold gate, it may actually be a nozzle assembly. “Cleansing” this seemingly obstruction often ruins the nozzle tip. To avoid damaging the nozzle, confirm the nozzle type of the hot runner system before taking any action. Ensure that all operators are well trained and can identify all different types of nozzles they handle.
3, Slide stop – For machines that run all year round, this work should be done once a week.
4, Cross-check the heater’s resistance – You should have measured the heater’s resistance when you first used it, so now’s the time to measure it again and compare. If the resistance fluctuates by 10%, consider replacing the heater to ensure it doesn’t fail at a critical point in the production process. If you never measured the initial resistance, do so now and use the value as a reference for future inspections of the heater.
5, Check for signs of wear between the guide pins and bushings – Look for scratches or abrasions, which are caused by a lack of lubrication. If these signs are new, you can extend the life of the pins and bushings by lubricating them more thoroughly. If the wear is severe, it’s time to replace the parts. Otherwise, the cavity and core may not fit together properly, resulting in uneven wall thicknesses.
6, Check the water flow – Connect a hose to the outlet and let water flow through the hose into a bucket. If the water isn’t clear or has a tint, rust may be present, while a lack of flow suggests a blockage. If these problems are detected, re-drill all pipes to ensure they are clear (or use whatever cleaning method you prefer). Improving your factory’s water treatment system can prevent future problems caused by rust and blockages.
7, Clean the ejector pins – Over the course of a year, ejector pins become dirty due to accumulated gas and film-like impurities. It is recommended to clean them thoroughly with a mold cleaner every six to twelve months. After cleaning, apply a layer of lubricant to the ejector pins to prevent scratches or breakage.
8, Check the radius area of the hot injection nozzle for breakouts – Breakouts are caused by loose, hardened plastic fragments remaining in the machine’s hot nozzle, which are clamped by the plastic barrel assembly during forward injection. The problem may also be caused by misalignment of the centerline.
Consider both possibilities when a fracture is discovered. If the damage is severe enough to prevent petaling (a term used by mold users in the past to refer to plastic leaking between the guide bushing and the machine’s hot nozzle tip), the sprue bushing should be replaced.
