2. Machining requirements1,keyway: JS9 for hub;2,Dimensional tolerance and machining allowance of casting shall conform to GB/T6414-1999 . 3, Cold shut, crack, shrinkage, penetration and serious defect such as misrun, mechanical damage is not allowed on the surface of casting:4,Casting shall be cleaned up, without burr, flash; spruing non-working surface flush with Casting surface; 5,Roughness of casting non-working surface by sand R shall be not more than 50m;6,According to industry standard, the position must be inverted when necessary;7,Groove dimension shall be checked before lining.