injection screws and few competent designers of generally larger-diameter extrusion screws. Robert F. Dray is the founder and owner of R. Dray Mfg. Inc., and the founder of Feed... reciprocating-screw injection-unit design manufactured by Egan Mfg. in the United States. Paul Squires first developed this design in 1950 at DuPont for use in the extrusion industry... is used to check the physical properties of the failed part. Processing Requirements and Screw Design Polymer melting requirements are the same for extrusion and injection molding. We...

on" production molding facility. Obvious hardware differences between Extrusion and Injection; L/D - Length divided by diameter (screw or barrel length /barrel inside dia.... or screw outside dia.) in extrusion is normally 30:1 or greater; in injection molding 20:1 is still the normal l/d. The l/d in injection is further reduced as the screw reciprocates. The... translated downstream in relation to the first feed flight. Injection screw designs normally have additional turns of feed section to compensate for this starvation (see figure 1...

on" production molding facility. Obvious hardware differences between Extrusion and Injection; (1) L/D - Length divided by diameter (screw or barrel length /barrel inside dia.... or screw outside dia.) in extrusion is normally 30:1 or greater; in injection molding 20:1 is still the normal l/d. The l/d in injection is further reduced as the screw reciprocates... translated downstream in relation to the first feed flight. Injection screw designs normally have additional turns of feed section to compensate for this starvation (see figure 1...

- 1975 BASIC PATENT NEW ADVANCES 1.) EFFICIENT SCREW 2.)"W" MIXER EFFICIENT SCREW DESIGN INVENTOR: R. F. DRAY. FILED 05/05/1970 PATENTED03/21/1972 ASSIGNED TO: FEED SCREWS, INC.... F. DRAY. FILED 09/15/1972 PATENTED01/29/1974 ASSIGNED TO: FEED SCREWS, INC. PATENT # 3,788,612 UNIQUE AREAS FIRST DESPERSIVE/DISTRIBUTIVE MIXER TO UTILIZE BI-BIRECTIONAL FLOW TO...History of Extruder Screw... THE HISTORY OF EXTRUDER SCREW DESIGN BY: R. F. DRAY AND R. B. GREGORY THIS HISTORICAL REPRESENTATION IS GENERATED FROM THE ACTUAL PATENTS. IN...