High Speed Slurry Flow Finishing of Inner Wall of Stainless Steel Capillary

Stainless steel pipe with fine hole and long size has recently needed for the flow line of pure gas and liquid, which is used in the field of precision machinery. Inner wall of such a pipe should be finished with high precision. Stainless steel pipes with different size of inner diameter are polished by flowing slurry at high velocity through the capillary. Finishing modes are examined in detail by scanning electron microscopy and profilometry. It is found from the experiments that the surface roughness of inner wall of as-received stainless steel pipe is reduced gradually with slurry passes, in which larger inner diameter of pipe has very enormous reduction rate in early stage of finishing. Usage of larger grain becomes to yield higher reduction of surface roughness. It is said that concentration of grain has a great effect on small inner diameter of pipe, but less effect on larger ones. Optical and scanning electron micrographs of the polished surface indicate that texture pattern of the inner wall disappears with slurry pass number, in which texture disappear in early stage of low pass number in small inner diameter of pipe, but not in larger ones.