The purpose of nitriding is to increase the surface hardness of the steel and improve its wearing properties. This treatment takes place in a medium which gives off nitrogen. In nitriding, nitrogen diffuses into the steel and forms hard, wear-resistant nitrides. This results in an intermetallic surface layer with good wearing and frictional properties. Our screws and barrels will get the hardness at surface about 900Hv~1000Hv, the depth of nitride layer will into 0.6mm and 0.7mm of nitride steel
Nitriding is done in gas at about 510oC (950oF). The process therefore requires steels that are resistant to tempering in order that the core strength is not reduced

# Nitride screw procedure ,
Prepare raw material→ Material heat treat(tempering and quench)→ Frame Machining→ Heat treating(setting)→ Produce details→ Milling→ Nitriding→ Polishing→ Inspection→ Delivery

# Nitride barrel procedure,
Prepare raw material→ Inner diameter machining→ Material heat treat(tempering and quench)→Produce details→ Milling→ Nitriding→ Polishing→ Inspection→ Delivery

合金处理
Bimetallic treating

Bimetallic hardening treatment is to spray and weld bimetallic alloy on the flights or inner bore of barrel, this bimetallic composite can be wear resistance, corrosion resistance or both, so screws and barrels to be longer life used.

To make bimetallic flight screw, we will make grooves on the flight of screw at first, then spray and weld bimetallic composite in it.

To make bimetallic single screw barrel, we have the facility to spray bimetallic composite centrifugally onto the bore of heated barrel. When barrel cooling down, the bimetallic composite will be adhered on the bore of barrel, the layer will be at least 2mm.

To make bimetallic twin screw barrel, we normall make 16pcs of grooves on the bore of front section of barrel, then spray and weld bimetallic composite. According to customer's requirements, we can make a bimetallic bush for the barrel,