Unpacking CASE

Do you know about Chemically Assisted Surface Enhancement or CASE? This metal surface treatment is sometimes referred to as Isotropic Superfinishing. This fascinating process is worth knowing more about.

CASE is a metal improvement process. The aerospace and automotive industries rely heavily on it for component safety. It strengthens components without reducing efficiency by loading additional weight to the structure. And, it’s vital in delaying and preventing cracks due to tensile stresses.

The CASE process involves shot peening and chemical techniques. These techniques produce a perfectly finished product with optimal surface integrity.


CASE achieves ideal surface roughness and stress characteristics along with mirror-like finishes. Additionally, it reduces surface fatigue and prevents pitting. Surface finishing technology is used during the manufacturing process, improving the all-round performance of components.

Benefits of Isotropic Superfinishing include:

  • Enhanced bending capabilities
  • Resistance to high-loading
  • Contact fatigue strength

Chemically Assisted Surface Enhancement is completed in these 3 steps:

Step 1

Firstly, the component is shot-peened. The shot peening process has proven benefits for the performance of the component. It reduces maintenance requirements and extends the lifespan of critical components.

Shot peening is a technique where residual compressive stress is induced. This is done by introducing controlled impact to a component’s surface. Spherical particles create small indentations as they hammer against the surface, changing their physical properties. The particles are usually made of steel, ceramic, or glass materials.

Shot peening works on the principle that denting a surface compresses the material beneath it. This controlled hammering produces beneficial residual compressive stress. It also removes undesirable residual tensile stresses.

Step 2

Dual peening is the second step in the CASE process. The peening is accomplished at a reduced intensity with a smaller shot size. This reduces surface roughness, further increases compressive stress, and improves surface hardness.

Step 3

Final processing involves polishing the component into a perfect finish. Surface area protrusions are gradually dissolved with a chemical solution of oxalic acids and non-abrasive finishing stones. The result is the smooth, mirror-like surface finish that we expect to see on new metal components.

CASE is applied to a wide variety of shapes and surfaces. A few examples of automotive parts include gears, seal faces, and transmission shafts.

Isotropic Superfinishing is an exact science and is vital to the manufacturing process. It extends the strength, efficiency, and safety of a variety of components. Its application prevents cracks and extends the lifespan of crucial parts.

It’s easy to take metal surface treatments like CASE for granted. Most of us don’t think about how the components making up the structures we rely on daily are made.

If you need any advice on types of metal fabrication, please contact Steelmor here.