... in all lines of machine precision shaft, now we have many kinds of different parts,such as spline shaft ... be up to 400,0000 set per year.2:We have already got the ISO900 certficate and take guarantee for ... With kinds of surface finished,such as heat treatment<we ourselves own one set>,black powder coating,Zinc,or ... Zink,8.Usual material we use is:15Mn,20Cr,1045,1035,A3,Q235, ...