Finishing of Metal Parts

Metal parts can be supplied 'as-built' or finished using various post processing and finishing techniques by our team of expert finishers. Dependent upon the material used, there are various forms of finishing available:-

Shot-peening

Shot peening is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of metals. It entails impacting a surface with shot (round metallic or ceramic particles) with force sufficient to create small indentations or dimples. It is similar to sandblasting, except that it operates by the mechanism of plasticity rather than abrasion: each piece of shot striking the material acts as a tiny peening hammer. In practice, this means that less material is removed by the process, and less dust created.

Shot peening may be used for cosmetic effect. The surface roughness resulting from the overlapping dimples causes light to scatter upon reflection. Because peening typically produces larger surface features than sand-blasting, the resulting effect is more pronounced.

Parts produced in Cobalt Chrome using DLMS:-

As sintered (Ra = 10 µm)	Shot-peened with Metal (Ra = 5 µm)	Shot-peened with Metal & Ceramics (Ra = 4 µm)

Polishing

Metal polishing is the process of smoothing metals and alloys and polishing to a bright, smooth, mirror-like finish. This can enhance the aesthetic appearance of parts as well as preventing corrosion, particularly those being used in automotive and aerospace environments. Medical instruments can also be highly polished to maintain hygienic conditions and prevent contamination in marks in the metals.

Polishing is a metal-finishing operation where articles are polished using abrasives or mops, in a multistage process. Firstly, coarse grit abrasives are applied at high speed to remove surface defects like pits, nicks, lines and scratches.Then fine grit abrasives are used to remove the residue and smooth the surface. Finally, cotton mops are used to give a mirror-like finish to the articles. Lubricants such as wax, diesel fuel and kerosene are used as lubricating and cooling media during these operations. Sophisticated computer-controlled machines can be used to polish intricately shaped articles, although much of this work can also be carried out by hand.

Example parts showing difference between 'as sintered' and polished finish