This paper is an attempt towards comparing experimental and theoretically results of forces obtained by varying interference. with of contact of the Tool and materials , calculated theoretically, may also be helpful for many production and design calculations. The fatigue strength can be increased by 50 to 100% or even more as a result of cold surface plastic deformation. Cold plastic deformation completely eliminates the unwanted stress raisers. Fatigue strength of machine components can be increased by plastic deformation. Various steels, cast irons and non ferrous alloys, all undergo favorable changes in their surface layers form fatigue strength view point as a result of cold plastic deformation. Surface of work piece hardening, perhaps the most effective method of increasing the fatigue strength of machine components. Use of cold plastic deformation increases the wear resistance of machine components. The explanation is that the relationship between the contact area and the force is near linear for these materials, and therefore the contact pressure force as a ratio of force to area is practically constant. In the case of hard metals (for example hardened steels) the significant elasticity causes the contact area to increase more slowly than the force. Therefore the contact pressure force for hardened steels increases with the Ballizing force. As the forces required are excessive, Tensile testing machine .The material of the ball is so selected that it is not suggests 2 to 3 percent interference between the ball and the hole. In the experience Hardened steel balls were used for low carbon, or medium carbon steel bushes. Aluminium bushed and the same hardened steel ball combinations were also used. Ball Ballizing is a mass production process for improving the accuracy and surface finish of holes.