Powder metallurgy refrigeration compressor connecting rod rust problem and its solution
Powder metallurgy products refer to metal or alloy parts manufactured by powder metallurgy process, which have certain porosity and organizational structure. Powder metallurgy products in the process of use, sometimes there will be a defect, called trachoma. Sand holes refer to small holes similar to sand particles on the surface or inside powder metallurgy products, which will affect the appearance, performance and life of powder metallurgy products. So, what is the cause of trachoma in powder metallurgy products? What are the effective ways to deal with it? This article will give you a detailed answer.
The main reasons for trachoma in powder metallurgy products are as follows:
- Poor raw material quality: if the raw material contains impurities, oxides, carbides and other incompressible substances, or the raw material particle size is not uniform, the shape is irregular, the surface is not smooth, etc., will lead to the gap when pressing, forming sand holes.
- Unreasonable process parameters: if the pressing pressure is too low, the holding time is too short, the mold temperature is too high or too low, the mold lubrication is poor, etc., will lead to uneven density of the billet, the combination is not firm, and the formation of trachoma.
- Unsuitable sintering conditions: if the sintering temperature is too high or too low, the sintering time is too long or too short, the sintering atmosphere is inappropriate, the sintering speed is too fast or too slow, etc., it will lead to uneven shrinkage of the billet, incomplete porosity closure, uncontrolled REDOX reaction, etc., and the formation of trachoma.
Improper post-processing operation: if the machining cutting speed is too fast, the cutting depth is too large, the tool material or shape is not suitable, etc., it will cause cracks or fall off on the surface or inside the body, forming sand holes.
The treatment methods of powder metallurgy products with sand holes are mainly as follows:
- Prevention first: do a good job of quality control in raw material selection, process design, equipment maintenance, etc., to avoid the possibility of sand holes.
- Inspection as a supplement: strict inspection is carried out after each process to find and remove the blank body or part with sand holes in time.
- Repair for repair: For parts that have sand holes, you can use filling method, welding method, penetration method and other methods to repair. The filling method is to fill metal powder or liquid metal with the same or similar material to the part into the sand hole, and pressure or heating curing. The welding method is to weld the metal wire or strip with the same or similar material to the part into the sand hole and polish or polish it. The penetration method is to soak the part in a solution containing metal or non-metal elements, and heat or electrolysis, so that it penetrates into the sand hole and forms a firm compound.
FOSHAN LAUNCH SINTER METALS CO.,LTD
Material: Mainly produce stainless steel base, iron base, copper base, copper and iron alloy base. Products: Gear, flange, G Bushing, positioning ring, rotor, counterweight, valve disc, VVT parts, clutch parts, oil pump parts, bearings.
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Address：No. 1-1 Maning Industrial Park, Xingtan, Shunde,Foshan,Guangdong, China
E-mail address：sales-7@launchpm.com
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