Injection Molding: New Alternative to Band Heaters For Small Injection Barrels

APSX LLC in Blue Ash, Ohio, is a manufacturer of aftermarket automotive electronics that designed and built its own desktop (7.5-ton) plunger injection machine to mold the plastic parts it needs (see March ’17 Starting Up). This experience gave the firm a first-hand appreciation of the limitations of standard band heaters, which are susceptible to damage, burnout, and frequent replacement. They also lose a substantial portion of heat to the ambient air.

In response, the two engineers who founded the company created their own barrel heater for their machine and any other of similar size. The new design encases four straight cartridge heaters in a 6061 aluminum housing. The heaters, surrounded by heat-transfer compound, are arranged parallel to the axis of the injection barrel and are spaced evenly around the circumference at 90° intervals.

Through extensive testing on the APSX-PIM desktop injection machine, the company claims that the new heater design improves heat retention and has greater durability and longevity than heater bands. What’s more, there is no need for internal thermocouples. The cost of the new heater is said to be comparable to that of a regular band heater with internal thermocouple.

The new heater is sized for the 2.5-in.-diam. barrel of the APSX-PIM machine, but it can also be used on other machines with the same barrel size. APSX says that if there is sufficient interest, the firm could produce similar heaters for different barrel sizes.