Introduction of Shot Blasting Process

1. What is shot blasting process?

Shot blasting process, which is also known as shot blasting strengthening, is one of the effective methods to improve the fatigue life of parts. Shot blasting process is to spray high-speed shot flow onto the surface of the workpiece, causing plastic deformation on the surface layer of the workpiece, forming a certain thickness of strengthened layer, and forming a high residual stress in the strengthened layer. Due to the existence of compressive stress on the workpiece surface, a part of the anti-stress can be offset when the workpiece bears the load, so as to improve the fatigue strength of the workpiece.

2. The use of shot blasting

Shot blasting is used to remove oxide skin, rust, molding sand and old paint film on medium or large metal products, castings and forgings whose thickness is not less than 2 mm or which are not required to maintain accurate size and contour. Shot blasting process is a cleaning method before surface coating, and it is widely used in large shipyards, heavy machinery plants and automobile factories.

Shot blasting is a cold-treating process, which is widely used to improve the  strength of metal parts that serve under high stress conditions for a long time, such as compressor blades of aircraft engines, fuselage structural parts, automotive transmission system parts, etc.

Shot blasting process is to spray numerous small circular media called steel shots onto the surface of parts continuously at a high speed under a fully controlled state, thus producing a residual stress layer on the surface. When each steel shot impacts the metal part, it hits the surface like a micro rod, knocking out small indentations or depressions. The surface of the metal is stretched when it is depressed. The grains compressed under the surface layer try to restore the surface to the original shape, so as to produce a hemispherical trace under the effect of high compressive force. Numerous depressions overlap together to form a homogeneous residual compressive stress layer. Finally, under the protection of compressive stress layer, the fatigue strength of the parts is greatly improved and the working life is prolonged.