Synchronized temperature contol of plastic processing equipment

[0033]Referring to FIG. 1, solid plastic feed material, typically in the form of pellets or powder, enters the feed end 1 of a barrel 2 for injection molding and extruding plastics, rubbers, carbon and like materials (hereinafter generally referred to as “plastic”). When entering the barrel, the temperature of the plastic feed material is low relative to a desired temperature during processing. The feed material then is sheared, mixed and metered by a screw that rotates within the barrel. The resulting molten material is forced out of the barrel under pressure through a nozzle or die at the discharge end 3 of the barrel 2.

[0034]To help melt the plastic, the barrel 2 is also heated with external electric resistance contact heaters 4, commonly referred to as band-heaters. Furthermore, the band-heater electrical circuitry is usually arranged so that the barrel 2 can be heated in multiple controllable zones 5, 6, 7 and 8 along the barrel's length. Usually three to six heating zones are use