The Injectavac™ furnace was pioneered by Centorr Vacuum Industries in the early 1980's for the debind and sinter of parts containing 1st and 2nd stage MIM binders. It has been updated for today's MIM technology to process injection molded parts from wax/polymer binder removal through sintering in one continuous cycle.
First stage wax binders are removed using a diffusion pump (subatmospheric evaporation) at dewax pressures less than 10-3 torr. A mechanical pump/blower combination is used at 1-20 torr pressures for 2nd stage Sweepgas™ Polymer removal, and final sintering is accomplished at partial pressures of 10-3 - 0.5 torr.
The heart of the system is our specially designed mechanical pump/blower combination for wax/polymer binder removal. It consists of a BRS™ Once-through oiling pump which continuously supplies fresh, clean oil to the compression chambers rather than recirculating oil from a sump. After passing through the pump, the oil is discharged to a collection container and binders/polymers that would normally contaminate the oil (or build up in the pump) pass through with the oil and are continuously discharged. In addition, the oiling technique enhances bearing and seal lubrication for long trouble-free pump operation.
Critical 2nd stage Polymeric binder removal is accomplished using CVI's patented Sweepgas™ technique where inert gas is bled into the furnace chamber and enters the work box, where it entrains polymers vaporized from the work pieces and carries them out towards the BRS pump. A chamber mounted binder pot collects small amounts of residue that collect on the chamber walls, while the balance continues on to the BRS system which pumps them directly through to the collection system while maintaining quality operations.