Why Burnish or Deep Roll?

Both burnishing and deep rolling cold work the surface of a workpiece. This cold working not only provides a highly polished surface, but also results in enhanced performance characteristics, such as increased strength and resistance to stress corrosion cracking.

ECOROLL is the world leader in developing burnishing and deep rolling technologies.

At the contact point, the tool force generates Hertzian contact stresses in the material’s edge zone, plasticizing the material’s top layer. When this stress is higher than the material’s yield strength, the material near the surface starts to flow.

As the tool moves across the surface, the elastically deformed material springs back, pushing the now plastically deformed zone into compression. As long as the tool or the workpiece continues to rotate, this forming process continues over the entire workpiece surface.

By plastically deforming the workpiece’s surface layer, both roller burnishing and deep rolling achieve a very smooth surface finish. The surface’s peaks are pressed down, almost vertically, into the surface and the material then flows into the valleys between the peaks.

The resulting smooth surface occurs because the material is plastically deformed — it flows.

Both burnishing and deep rolling change surface microstructure. The material characteristics achieved depend on the amount of cold work and the material’s properties.

The Deep Rolling Difference

Deep rolling is similar to roller burnishing, but combines burnishing, cold working and the generation of compressive stresses in the edge zone. Together, these three physical effects increase fatigue strength and reduce or even prevent stress corrosion cracking.

Simultaneously, the deep rolling process induces compressive residual stresses. By precisely controlling the rolling pressure (or burnishing force), ECOROLL tools can produce the specific stress characteristics required for a given workpiece.