screw caps for injectoin machineinclude (screw caps,ring seat, ring valve),Accessories for screw According to the customer design to manufacturing. ... screw and barrel as like screw caps,ring seat, ring valve ect.,TECHNICAL DATA Depth of nitration case:0.4-0 ... .4μmScrew straightness: 0.015mm/m Chrome plating thickness: 0.01-0.1mm Fully hard screw(wear-proof, corrosion-proof, heatproof ...