Isotropic Finishing (Superfinishing)/Case Finishing

Applications

CASE sm is ideal for surfaces that require both excellent fatigue strength and surface finish due to contact loading. This technique has proven effective in improving resistance to macro and micro pitting of gear teeth flanks and failure mechanisms that limit the performance of many gear designs.

For example, transmission gears utilised in aerospace, automotive racing and off-highway applications are required to run reliably under high root bending loads and tooth flank contact loads. CASE sm has proven success in all these industries.

Surface finishes of better than 0,25 microns (Ra) are attainable with CASE sm on carburized, nitrided and induction hardened gears.

Process

CASEsm, is a two-stage process developed by Metal Improvement Company (MIC) to extend a component's surface fatigue life beyond that provided by Shot Peening alone. CASEsm consists of Shot Peening followed by Isotropic Finishing. The Isotropic Finishing involves traditional vibratory honing techniques which remove the asperities left from Shot Peening and/or machining but retains shallow micro-indentations for lubricant retention.

Secondary processing by Shot Peening (Dual Peening) at a lower intensity and modified shot size will have the effect of reducing roughness, increasing the surface stress and increasing the cold work of the near surface area will give additional benefit.

  • Surface reduction to mirror like finishes
  • Optimum surface roughness and stress characteristics
  • Reduced contact/surface fatigue
  • Increased lubrication retention, heat transfer and reduced noise
  • Good rounding ability to sharp edges for ease of handling and assembly
  • Reduced manufacturing times and production costs
Isotropic Finishing (Superfinishing)Isotropic Finishing (Superfinishing)