general purpose screws, standard screws

The term “GP screw” or “General Purpose screw” has been used erroneously for many years to describe a single flighted feedscrew. While you can generally use such a screw and process around it with a number of different polymers, very rarely is it the proper screw design for any application. Even if a machine is going to be processing a variety of polymers under many different conditions, custom designing an advanced feedscrew design is going to yield much better results. Yashi Screw’s engineers will evaluate your processes and materials and custom design your “General Purpose screw” to meet all of your requirements.
Our engineers have extensive experience in designing general purpose and special purpose screws for plastics processing.
Functions of a Plasticating Screw include:
Feed the resin consistently.
Melt the resin uniformly.
Pump the fluid steadily.
Mix the resin homogeneously.

The general purpose (GP) screw, if designed properly, can perform these functions satisfactorily. The selection of the proper injection molding screw design for a given processing environment should be based on the resin or resins to be processed. There are no standards in the plastics industry for a general purpose injection molding screw design.

The OEM general purpose injection molding screw designs are each different. A processor must be diligent in understanding an OEM GP design and how it will affect the way the resin melts. Each design will process differently.

In an injection molding factory utilizing machines manufactured by different OEMs,  due to the different OEM GP designs, obtaining the proper residence times and shear rates to achieve an homogeneous melt quality on each machine may be difficult to do. Some resins cannot tolerate high shear rates, higher temperatures and/or longer residence times.

Yashi Screw has a good reputation for developing custom and general purpose injection molding screw designs.

Base Materials:
Alloy Steel: 4140 steel(AISI 4140), Nitralloy 135M, or equivalents.
Stainless Steel: 304, 316, 416, 17-4PH
Tool Steel: AISI D-2, H-13, DC53, CPM 9V, CPM 10V, JIS SKD11, SKD61
High Nickel Alloys: Hastelloy C-276, Inconel 625, Inconel 718
Flight Hardfacing Materials:
Nickel base: Colmonoy #56, Colmonoy #57, Colmonoy #83, Colmonoy #88
Cobalt base: Stellite #6, Stellite #12
Surface Hardenings:
Gas nitriding and Ion nitriding, Chrome plating, Carbide encapsulating, PVD coating, etc.

injection molding screw, screw tip assemblies, screw head, check ring, non-return ring, seat ring, rear seat

gruppi di plastificazione, viti e cilindri di plastificazione ( viti, cilindri, puntali, teste e ugelli ),