What is the Difference between Shot Blasting and Shot Peening?

2 workers seen through a shot peen

Shot peening and shot blasting are two common processes used in the manufacturing industry. Industries that employ metal parts rely on these processes for achieving different objectives. Manufacturers choose one method over the other; here are the differences between the two processes.

Shot Peening

Application of stress onto a metal surface can strengthen its properties. Such application of pressure relieves tensile stress while adding a layer of compressive stress to the metal piece.

Peening refers to the process of increasing the strength of a metal surface. Traditionally, a metal used to be struck with a ball-peen hammer to strengthen it. However, in today’s large-scale manufacturing, such traditional methods have been rendered useless. Instead, mechanical shot peening is employed.

Shot peening works by shooting a stream of material against the metallic surface. Each shot acts like a ball-peen hammer, making the metal surface stronger and resistant to cracks and corrosion. Shot peening is also employed to render a textured surface to the metal part.

Shot Blasting

Metal parts typically require a coat of paint for welding work before they can be finalised.  It is important for the surface of the metal to be clean to perform these processes. Shot blasting is the process of preparing metal parts for further treatments, such as welding or powder coating. It is a crucial step that ensures the coat adheres properly to the metal part. Shot blasting can be used to remove contaminants, such as oil and dirt, eliminate oxides like rust, or smoothen the surface of the metal.

The metal surface is exposed to a pressurised stream of abrasive material, also called shots. The shots may be propelled using a centrifugal wheel (wheel blasting) or using a pressurised fluid like compressed air.

The final results depend on the size, density and shape of the shots. Some examples of shots that are used in shot blasting include aluminium pellets and copper shots.

These processes are an improtant part in the maufacture of metals, of which the modern world depends on in many ways.