After precision machining, magnetic testing was carried out, and the impedance composite muffler was demagnetized. Technical difficulties: in order to complete the camshaft processing and meet various precision requirements, it is necessary to put in the profiling or CNC processing equipment to ensure that the contour processing of the three cams on the shaft meets the requirements. Now the company is short of funds, unable to purchase equipment, processing projects in hand can not be implemented. In the case of no obvious decline in heat transfer performance, a kind of chemical film which can fully protect the surface is developed to solve the corrosion of aluminum plate fin muffler heat exchanger in specific working environment; a fin forming mold with fin spacing of 1.0 mm and fin thickness of 0.25 mm is developed, and the design pressure of the fin can reach 6.0 MPa; the common quality problem is between the two pipelines The leakage of single-layer pipeline or string leakage. Can most of the external leakage or series leakage be solved under the premise of properly reducing the pressure bearing capacity? High strength aluminum alloy: it is suitable for vacuum brazing process. Using the existing vacuum brazing furnace, high strength aluminum alloy is used to adapt to the design pressure of 40bar plate fin air-cooled heat exchanger.