1. causes of residual stress
a. When cutting in Dongguan CNC processing plant, plastic deformation occurs in the surface metal layer, which makes the specific capacity of surface metal increase. Because plastic deformation only occurs in the surface metal, the specific capacity of the surface metal increases and the volume expands, which inevitably is prevented by the inner layer metal connected with it. Therefore, the residual stress is produced in the surface metal layer, and the residual tensile stress is produced in the inner layer metal.
b. In cutting, a large number of cutting heat will be produced in the cutting area.
c. Different metallographic structures have different density and different specific capacity in Dongguan CNC processing plant. If the surface metal has changed the metallographic structure, the change of the specific capacity of the surface metal must be hindered by the matrix metal connected with it, so there will be residual stress.
2. selection of final process processing method of main working surface of Dongguan CNC processing plant: the selection of final process processing method of main working surface of parts is very important, because the residual stress left by the final process on the working surface will directly affect the use performance of machine parts. The specific working conditions and possible failure modes of the main working surface of the part must be considered when selecting the final working procedure processing method of the main working surface of the part.
Under the action of alternating load, local micro cracks on the surface of machine parts will expand the primary cracks due to tensile stress, and finally lead to the fracture of parts. Considering the improvement of the fatigue failure of parts, the final process of the surface should choose the processing method which can produce residual compressive stress on the surface