We have three production lines for internal gears also calls ring gears like spur ring gears and helical ring gears ,usually spur ring gears will be done by our broaching machines to meet ISO8-9 accuracy ,if broaching plus grinding which could meet ISO5-6 accuracy ,however helical ring gears will be done by our power skiving machines ,which could meet ISO5-6 accuracy well ,which was more regular for small helical ring gears .