Gear precision is refers to on gear shape of integrated errors by divided of a grade, which including tooth shaped, and tooth to, and diameter jumped, some important of parameter, which tooth shaped is refers to tooth of radial shape, tooth to is refers to tooth of longitudinal shape, diameter jumped is refers to adjacent two tooth between distance of errors, General we car with of gear can by roll tooth machine processing completed, 6~7 level will can using, and some press due to need high-speed running and bulk printing, so need high precision gear to reduced gear cumulative by caused of errors and makes printing effect declined, Domestic production of grinding machines can process up to 4~5 level, imported high-precision grinding machines can process up to 3,~4 level, and some can be processed to level 2. Japan standard DIN level 0 is equivalent to level 4 of the Chinese General error in μ m units, 1 u m=0.001mm