Users are increasingly demanding the quality of automobiles and their parts. Brakes are the key components of automobiles and their product quality and functional reliability are particularly important. Brake pump leakage is one of the most prominent quality problems in automotive parts. It is a hidden quality problem. The manufactured product can not find the problem from the appearance, it will not produce oil seepage phenomenon at the beginning of use, but after using for 1 month or more, some products will see oil seepage. This phenomenon occurs in many products. It all happened. To solve this problem has some difficulties, and the verification is more difficult. In recent years, the author has carried out some explorations and studies on the oil leakage problem of the sub-pumps. In terms of the key factors affecting the oil leakage of the brake sub-pumps and their solutions, some conclusions have been drawn. Experience and effective methods are described below. Choosing a reasonable method of precision machining of the cylinder bore, and strictly controlling the roughness of the cylinder bore, the machining process of the cylinder bore of the cylinder bore using the finishing method of the cylinder bore grinding. There are two ways of finishing: rolling and grinding. Rolling process is currently a more advanced finishing process, but the material is HT250's sub-pump. During the blank manufacturing process, due to the slight changes in the material and casting, aging treatment, the partial hardness of the sub-pump rough is uneven. Rolling pressure is difficult to flatten the local hard spots, the surface of the pump hole during the rolling process will also increase the hardness, the local contour peaks and valleys of the cylinder hole (the peaks and valleys will accelerate the wear of the sub-pump bowl, damage the cup and oil spills ), it will be more difficult to eliminate. In addition, due to the poor plasticity of the cast iron material, it has notch sensitivity. After being calendered, the surface of the cylinder hole is serrated at the microscopic level. During the use of the brake, the piston of the cylinder is moved axially, and the lip of the cup is under high pressure. With the cylinder hole activity, axial grooves are drawn, resulting in oil leakage. 3D Folding Face Mask,3D Folding Protective Mask,3D Foldable Ffp2 Respirator,3D Folding 5 Layer Disposable Respirator Henan Aklly Filter Engineering Co., Ltd , https://www.akllyfilte.com