Shot Peening

Shot peening is a process used to finish metal to prevent fatigue and stress corrosion failures and help to increase product life cycles. When shot peening products, small spherical shot is blasted against the surface of the part causing dimples in the materials surface. These dimples overlap each other, which in turn causes the material to be work hardened on the surface and on the deeper level has residual compressive stress. The benefits of shot peening are:

  1. The spring surface is harder (stronger)
  2. The wire surface is smoother and more consistent with wire drawing marks being removed
  3. There will be a residual compressive stress on the inside surface of the compression spring where the supplied stress in service will be a maximum.


Stainless steel components that need an extra resistance to rust and corrosion can be passivated.

Passivating involves thoroughly cleaning and then soaking the spring in an acid bath so that when the springs are removed from the acid the surface is uniformly oxidised creating a protective barrier on the component.

We passivate to the ASTM A967/A967M standard.

Bright Zinc Plating

Bright Zinc Plating is a process that plates the spring with zinc. This adds an additional layer of protection against corrosion, but it is also used to apply a bright and shiny surface for appearance.

Delta Toning

Delta Toning is a micro layer zinc flake coating that provides a greater level of corrosion resistance for when it is really needed. Some advantages of delta toning are:

  • Sacrificial cathodic protection
  • Barrier-effect due to zinc and aluminium flake
  • Reaction of binding systems with base
  • Consolidation of Delta-Tone 9000 film under corrosion loading

Chemical Blacking

Chemical Blacking is a metal finishing process that provides the many ferrous materials with a protective and decorative black coating. The formation of the black oxidised coating strengthens the component with impressive anti-chip and anti-scuff properties, and the process does not alter the dimensions of the component.

Finish & Coating

If there are any other finishes or coatings that you need for your product we can provide them. This includes colour passivating, painting or dyeing for identification purposes.

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