With isotropic superfinishing, a component is firstly shot peened, to create multiple indentations in the surface using the spherical shot media from which it draws its name. As each indentation is made, the surface will try to yield, but is restrained by the substrate, introducing a residual compressive stress and removing any prior manufacturing-related tensile residual stresses. This proven technique makes the surface resistant to crack initiation and propagation.
Secondary processing by further shot peening (or dual peening) at a lower intensity with modified shot size will have the effect of reducing surface roughness and increasing the compressive stress and cold working of the near surface.
Final processing is then carried out in a controlled and gentle manner using non-abrasive finishing stones together with oxalic acids: here, the most positive or peak surface areas are progressively removed, producing a mirror-like surface finish with an extremely low surface roughness.
Some of the most common applications for isotropic superfinishing by Metal Improvement Company include the manufacture of gears, transmission shafts, bearings, cams and cam followers, journals, seal faces etc. Key benefits of isotropic superfinishing include achieving the optimum surface roughness and stress characteristics, being able to produce mirror-like finishes, the reduction of contact/surface fatigue and the prevention of micro and macro pitting. CASE is just one of many surface finishing options available to discuss on the Metal Improvement Company stand at the forthcoming Engineering Materials Live event on March 12th.
Entry to the Engineering Materials Live event is free of charge by pre-registration. The event takes place at the acclaimed British Motor Museum, located adjacent to the Aston Martin and JLR plants at Gaydon south of Warwick and just 1 minute from the M40. There is abundant free parking, and for visitors arriving before 1030, a free bacon roll and brew too. Tea and coffee is provided free of charge all day at the event, and pre-registered exhibition visitors can also visit the superb Museum, with almost 300 fascinating cars on show, free of charge too (standard adult entry fee otherwise is £14.50).