Specification: Screw diameter: d15- d 300 L/d ratio: 15-46 Product classification: Aiming at different plastic products the screw can be chosen from: general type, pin type, barrier type, separation type, and gas-exhausting type, etc. Base materials: (1)38crmoala(jis sacm645) (2)42crmo(aisi 4140) (3)4cr5mosi v1 (jis skd-61) (4)9cr18mov (5)hpt Bimetallic alloy materials: 1)fe-based alloy 2)ni-based alloy/deloro alloy 3)co-based alloy 4)nico-based alloy 5)tungsten carbide/wolfram carbide Technics: Heat treatment High-frequency quenching Nitriding treatment Hard-chrome electroplating Bimetallic alloy welding Bimetallic alloy centrifugal casting Technical parameter: Nitrided layer depth: 0.5-0.8mm Nitrided hardness: 900-1000hv Nitrided brittleness: less than grade 1 Surface roughness: ra0.4 Linearity of screw: 0.015mm Hard-chrome plating hardness after nitriding: >950hv Chrome-plating layer depth: 0.025-0.085mm Bimetallic layer depth: 3mm Slushing oil coated& film wrapped in wooden case