7 Auxiliary Equipment Process Tips for Injection Molding

             “Auxiliary Equipment” is considered any additional equipment required for assisting the primary equipment (molding machine) in producing the final production of the molded parts.

It includes items such as granulators, mold temperature controllers, hopper loaders, and the like.

These should not be confused with “Secondary Equipment” which is considered additional equipment required for manipulating the plastic parts after they have been molded.

This would include drilling machines, paint systems, packaging equipment, and the like. 

Auxiliary Equipment Injection Molding

If robots are used for removing molded parts from the molding machine they are considered auxiliary equipment.

If they are used for picking molded parts from a container and placing them in shipping boxes they are considered secondary equipment.

  1. Always keep your hopper cover in place. One major source of material contamination is ceiling debris such as dust, water condensation on overhead pipes, and other air-borne trash. 
  2. Before filling an empty hopper, make sure your hopper is clean. Blow it out with air to remove any dust that may be present. Then use a clean shop rag sprayed lightly with vegetable oil (such as PAM) and wipe down the walls inside the hopper to catch any fines that might be left from the last run. Do not use paper towel as this will leave paper dust which will cause defective parts.
  3. Make sure the screen in your granulator (grinder) has the proper hole and space settings for making regrind from the material you are grinding. If the holes are too large the regrind material will take much longer to melt than the virgin it is mixed with. That can result in an improperly structured “melt” and will cause defective molded products. 
  4. Mold temperature controllers are designed to “maintain” a predetermined temperature of the injection mold by circulating water (or in some cases, oil for mold temperatures above 200 degrees F) through the mold using hoses connected to metal fittings or pipes on the mold. The controller compares the average temperature of the circulated water to the preset desired temperature and either adds cold water or adds more heat (using electric heater coils) to make sure the mold keeps a stable temperature for molding. Understanding this process is necessary for knowing how to control it. 
  5. -There is an indicator on the unit that displays the temperature setting you have set for the mold you are running. BUT, that is NOT actually the temperature of the mold. So if someone were to ask you at what temperature are you running your mold you should NOT tell them the seting on the water control unit. You should actually take a pyrometer and check a few points on the molding surfaces of the mold in an open position. You will find there may be a big difference between those two values.
  6. Vacuum loaders are commonly used for transporting material from a container to a hopper on the molding machine. Due to friction a buildup of dust will accumulate inside the clear plastic hose used for that transporting. When changing material types or colors it is critical to remove that fine dust caused by the previous material. You can use a clean shop rag to clean the dust away by simply placing it in the hose and vacuuming it through to the hopper. Repeat as necessary, and on the final trip lightly spray the rag with PAM (or you can use a very light coat of mold release spray). This will aid in getting the last few particles of dust and will also help keep dust from forming during the next molding run.
  7. – A machine’s hopper is designed as a basic unit that holds approximately 2 hours worth of generic polystyrene. The bigger the machine, the larger the hopper but it is still designed for 2 hours’ worth of plastic. The reason is that the machine manufacturers know that plastic material must be dried prior to molding but that it only stays dry from 2 to 4 hours after the initial drying activity. Hopper extensions are available but should only be used if hopper dryer units are also installed to keep the plastic dry while it resides in the hopper.