How to polish the surface of the welded neck flange?

- Sep 19, 2019-

After the welding neck flange is generally polished after the production, then everyone knows how to do the polishing of the welding flange? The following technical staff of the welding flange manufacturer will give you a brief introduction. I hope I can help you.


There are generally three methods for solder flange polishing: chemical polishing, spot polishing, and mechanical polishing.

welded neck flange

Chemical polishing of the butt flange: Chemical polishing is to make the material in the chemical medium, the microscopically convex part of the surface is preferentially dissolved, so as to obtain a smooth surface. The main advantage of this method is that it can polish a workpiece with complex shapes without complicated equipment, and can polish many workpieces at the same time with high efficiency. The core issue of chemical polishing is the formulation of the polishing fluid. The surface roughness obtained by chemical polishing is generally several 10 μm.


Spot welding of the welding flange: the metal ions detached from the workpiece and the phosphoric acid in the polishing liquid form a phosphate film adsorbed on the surface of the workpiece. The mucosa is thinner at the convex portion, and the concave portion is thicker due to the convex portion. The current density is high and the dissolution is fast. As the mucous membrane flows, the irregularities are constantly changing, and the rough surface is gradually leveled.

Mechanical polishing of butt weld flange

Mechanical polishing of butt weld neck flange: mechanical polishing is divided into rough polishing and fine polishing. The rough polishing is carried out on the electric polishing disc at a speed of 200-300 rpm. During the rough polishing process, coarser chrome oxide, aluminum oxide or magnesium oxide polishing solution should be properly sprinkled and the wool on the polishing disk should be kept moist. During the rough polishing process, the sample is taken up and reciprocated along the radial direction of the polishing disk to uniformly adjust the applied pressure, taking care that the pressure should not be too large.


When polishing starts, sprinkle some polishing liquid from time to time. Slowly reduce the pressure later, reduce the concentration of the polishing solution until the polishing to the fine wear marks disappears, the light is flat and there is no black spot. The rough polished sample is washed with water and then finely polished, and finely polished to remove the wear marks left by the rough polishing, so that the polished surface is bright and flat. The polishing machine used for fine polishing is basically the same as that used for rough polishing, and its rotation speed is 150-200 rpm.