The patent pending Inject-Ex™ System is an improved Injection Molding process that employs a non-reciprocating (stationary) helical plasticating screw housed within a heating/cooling cylinder that is coupled to a plunger head assembly, drive housing and motor that conveys, melts, homogenizes and injects molten polymeric material more precisely and efficiently, along one axis, comprising a unitary Inject-Ex™ Unit.
The Inject-Ex™ addresses three major deficiencies of the reciprocating screw design; a. Viscosity variation in part caused by poor melt preparation and homogenization b. Variations in the quantity of melt dispensed due to poor/inconsistent closure of the NRV c. Continuous pressure changes across the shutoff plane due to melt decompression inconsistencies and viscosity changes due to heat input. Due to these variations the molding machine is not “smart“ enough to know when to trigger V.P. transfer positions or to determine the amount of mass that was displaced each shot without the use of expensive in-mold cavity sensors and additional processing power. The Inject-Ex™ System’s unique mechanical design addresses these deficiencies and delivers a more precise shot.
Inject-Ex™ plunger technology explanation. Polymer is conveyed, melted, homogenized, distributed and pumped downstream with the stationary Posi-Melt™ plasticating screw, through the patented plunger head displacing volume into the pressure vessel which forces the unitary Inject-Ex™ assembly to traverse in an upstream direction to a predefined position. The normally closed plunger head that is attached to the distal end of the barrel and is fit tightly with the pressure vessel is designed to open on pressure allowing the molten polymer to flow into the awaiting pressure vessel. By virtue of the kinetic energy of our springs that are a component of the plunger assembly, the poppet closes instantly upon screw stoppage. The precise instantaneous closure and tight diametrical fit with the pressure vessel allows the plunger head to act as a piston for precise mass displacement into the pressure vessel and subsequent distribution into the mold which occurs along ONE axis, eliminating the dead spots or temperature issues that are prevalent in the state of the art two component plunger systems. The technology is currently designed to process; 1. Thermoplastics 2. Thermoset LSR materials.
a. Stationary Posi-Melt™ screw that provides a consistent output-recovery time, no disruption of solids bed compaction, each pellet is subject to the same heat and shear history, and a well dispersed and homogenized melt pool
b. Smaller footprint/output
c. Inline polymer flow for less energy usage and pressure drop
d. Ultra precise shot control as a result of utilizing our patented mechanical shut-off mechanism/plunger
e. The use of a Temp-Sense™ Melt Sensor for melt density verification
f. Less parts/pieces compared to a screw/pot machine design for a smaller carbon footprint
g. Can be programed to behave like an injection blow or low pressure injection unit
Inject-Ex™ Benefits to the Processor:
1. Instantaneous independent mechanical shutoff of the plunger head isolates the melt pool from the screw melting chamber. This feature allows for discrete monitoring and control of the melt pool for improvement in shot control.
2. More precise volumetric change of the melt pool if melt decompression is used.
3. Since shut-off occurs mechanically and is independent of the motion of the screw/plunger assembly, smaller shots that require less mass displacement will have greater control.
4. No change in solids bed compaction due to melt decompression.
5. No need for melt decompression to seat the NRV.
6. Additional programming logic can be utilized during recovery to minimize shot variation by keeping the screw in a fixed axial position while rotating the screw to pressurize the melt pool for precise density.
7. Overall energy efficiency due to a more isolated direct melting process for lower operating expenses…less energy/unit mass output.
8. The isolation between the melting chamber and melt pool allow for a more precise measurement of volumetric mass displacement and hence good-bad part discrimination using our Melt-Profiler™ Melt Sensing Technology allowing for 24-7 part history records and good-bad part discrimination.