... Popular product,high quality. Hot Sale Pressure FH FHS FHA Riveting Self Cinching Screws 1.Product Specification... Raw Materials 1. ... special standard according to the drawing.GradeClass 4.8, Class 6.8, Class 8.8, Class 10.9, Class 12.9,etc. ... specific order quantities.Production flowHeading→washer assembly→Threading→Secondary machine→heat treatment→plating→Anti-slipping→Baking→QA Inspection&sorting→ ...