... Germany 4)wear resistant,prevent rust,no burr Corrugated cardboard spacer :1)Hardness:HRC 61-622)Diameter:250mm ... cardboard spacerMaterialSKH etc.Diameter232-270mm or depends on the customer's request ,samples and drawingThickness7,7.5,10mm ... pressing,sintering,milling grinding ,Germany grinding machine ,CNC machine etc.7)Advantages: Corrugated cardboard spacer has good abrasion resistance and high ...