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How do you make your bimetallic screw coating?


Currently there are 4 popular screw coatings in our injection and extrusion screw production:


1) PTA coating screws

PTA (Plasma Transferred Arc) is a welding method, it’s traditional and most widely used in bimetallic screw coating process, thus most economical as well. More importantly this works most alloys.

PTA coating thickness is about 1.5~2.0mm.


2) PVD coating screws

PVD screw coatings are thin film coatings where a solid material is vaporized in a vacuum chamber and deposited onto the screw. It is used to change the surface properties of the screw, where new mechanical, chemical, electrical or optical characteristics are needed.

PVD coating Thickness is about 0.004~0.006mm.


3) HVOF coating screws

HVOF coating (High Velocity Oxygen Fuel ) process is when fuel and oxygen are fed into a combustion chamber and ignited and combusted continuously.

The jet of hot gas and powder (spray stream) is directed towards the screw surface to be coated. The powder partially melts in the stream and deposits upon the substrate. The resulting coating has, among other attributes, very low porosity and high bond strength.

HVOF coating thicknesses ranges between 0.05mm to a few mm.

4) Hard Chrome-plating screws

Chrome-plating is quite normal in our life.

Hard chrome-plating thickness for screws is about 0.02~0.03mm.


Please be free to contact your EJS representative to select your best-to-go screw coating for your machines.