1, see if the specification model is suitable When purchasing Sheet Metal Parts, first find out what type of machine parts are, and then ask if they are the specifications you need. For example, when purchasing electrical parts, check whether the voltage and power of the replaced parts are consistent. When purchasing the transmission belt, pay attention to whether the model and circumference are consistent. When purchasing the fuel injection head, pay attention to the diameter of the nozzle and the angle of the atomizing cone. Whether it is accurate; when purchasing pistons and piston rings, it should be distinguished whether it is standard or enlarged. 2, see if the trademark logo is complete The package name and box should be marked with the product name, specification, model, quantity, registered trademark, factory name and telephone number. Some large or important parts are also equipped with instructions for use, certificate of conformity and seal of inspector when they are shipped. They should be recognized when purchasing, so as to avoid the purchase of counterfeit and shoddy products. 3. See if the joint is flat. For joints, especially those with sudden changes in diameter or welds with welds, see if there are burrs, defects or cracks in the joint. 4, see if the surface of the part is rusted Whether the metal parts have rust spots on the surface, whether the rubber and plastic parts have obvious aging, cracking, loss of elasticity, and whether the shaft parts have obvious turning lines on the surface of the journal, if any, should be exchanged. 5, see if the protective surface is intact The piston pin and the bearing bush should be protected by paraffin. The piston ring and the surface of the cylinder liner are coated with anti-rust oil and wrapped with wrapping paper. The plunger pair, the outlet valve pair, the needle valve pair, the valve, the piston, etc. are immersed in anti-rust oil and pressed with plastic sleeve. Sealed. Nbstarlite is a professional parts supplier, can provide you with a variety of professional Bakelite Parts and other parts series, no matter what kind of products you need, we will do our best to meet you, so come and contact us.