TPT March 2010

F inishing , E nd F inishing & S uperfinishing “Superfinishing can give a surface finish of 0.01 μm.” To grasp the sense of one one-hundredth μm, the reader of a paper on tube superfinishing has first to revisit the definition of μm. An µm (micrometre, or micron) equals one-millionth of a metre. Visualisation is of limited use here. The capability of such a process must be seen in the benefits it delivers: greater wear resistance, improved load-bearing properties, tighter seals, longer part life, fourfold durability. While this is impressive, the commitment to precision that makes such results possible is not unique to micromachining but standard throughout the finishing specialities. A routine end-finishing job will involve careful consideration of materials and wall thicknesses; dies and arbors, heads and blades, facing and centring; spherical radii, spindle speeds, cycle times, and parts counting – and much, much more. With working to extremely close tolerances the industry norm, it would come as no surprise – certainly not to the professionals whose products and services are reviewed in this section – if the results of even the simplest de-burring operation were to prove accurate within a very few µms.

Grind Master’s square tube polishing machine