①The influence of material density is steel ball, cast iron ball, alloy steel ball and so on. The density of different materials is different, the density of steel is bigger than that of cast iron, and the alloy steel is different according to the density and content of main alloy elements.

②The influence of steel ball manufacturing method: the steel balls produced by rolling and forging are compact and dense, and the microstructure of cast steel balls, cast iron balls or cast alloy balls is not very dense, or even stomata, so the density is smaller.

③The microstructure of steel ball affects the density of martensite, austenite, bainite, ferrite and other different crystal structures, and also influence the crystallinity of the steel.

④The influence of chemical elements: as the chemical composition of steel ball is different from those of iron, carbon, chromium, manganese, sulfur and phosphorus, it has different effects on the hardness and impact wear of steel ball. Generally speaking, the steel ball has high wear resistance when it contains large amounts of chromium.