Specification: 45/90, 45/100, 50/105, 51/105, 55/110, 55/120, 58/124, 60/125, 65/120, 65/132, 68/143, 70/135, 70/140, 75/150, 80/143, 80/156, 92/188 The above are standard specifications, we can customize according to customers' requirements. The compression ratio of screws can be designed according to different products and ingredients. Base materials: 1)38crmoala(jis sacm645) 2)42crmo(aisi 4140) 3)4cr5mosi v1 (jis skd-61) 4)9cr18mov 5)hpt 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: ¡ý 950hv Chrome-plating layer depth: 0.025-0.085mm Bimetallic layer depth: 3mm Slushing oil coated& film wrapped in wooden case