A reasonably designed fixture is right. Landlords and turners must know that rough turning and fine turning are separate. Some people are self-righteous and ignore it. It must be the deformation of thin-walled workpiece, and some outer circles or inner holes cannot be clamped hard. Fixtures should be made reasonably according to different workpieces, and proper circles, holes and surfaces should be used to support the clamping force of workpieces, the cutting force of cutters and the tolerance of workpieces, so as to achieve the purpose of small deformation of workpieces. It is impossible to control the thin-walled workpiece to the minimum range without deformation. There is also a hot deformation finishing car before water cooling, and the car is expected to mine after it is determined by hand that it is not hot.