1, the internal force effect leads to parts processing precision changes in lathe processing, usually using the effect of centripetal force, with the lathe of three or four jaw chuck, the parts clamping, and then processing of mechanical parts. At the same time, in order to ensure that the parts in the force does not loosen, reduce the effect of internal radial force, must make the clamping force is greater than the mechanical cutting force. The clamping force increases and decreases with the increase of cutting force. Such operation can make the mechanical parts in the process of processing force stable. However, after the release of the three-claw or four-claw chuck, the machined parts will be far from the original, some polygon, some oval, showing a large deviation

2, the elastic deformation caused by external force effect in mechanical processing parts show elastic deformation of the main reasons for several aspects. First, if the internal structure of some parts contains thin slices, there will be higher requirements for the operation method, otherwise, when the operator locates and clamps the parts, it cannot correspond with the planning of the drawings, which simply leads to the occurrence of elastic deformation. Two is the lathe and fixture is not smooth, so that the parts in the fixed on both sides of the force is not uniform, resulting in cutting the force effect of the small side under the effect of force will appear translation parts deformation. Third, the positioning of parts in the processing process is not reasonable, so that the rigidity of parts decreases. Fourth, the existence of cutting force is also one of the reasons for the elastic deformation of parts. The elastic deformation caused by these different reasons explains the influence of external force on the machining quality of mechanical parts.

3, after heat treatment, the problem of simple deformation for thin section mechanical parts, because its length diameter is very large, after heat treatment, the simple straw hat twists and turns. On the one hand, there will be a phenomenon of center bulge and increase of plane deviation. On the other hand, due to the influence of various external elements, the parts will be tortuous. These deformation problems occur not only because the internal stress of the parts after heat treatment has changed, but also because the professional knowledge of the operators is not thick, do not know the structural stability of the parts, and then increase the probability of deformation of the parts.