Sintered powder metallurgy parts can be finished or treated like any other metal parts to obtain the required characteristics-corrosion resistance, improved strength and hardness, surface wear resistance, edge sharpness elimination, porous sealing, and size and surface Control of finish. Electroplating, coating, deburring, welding, furnace brazing, heat treatment and steam treatment are secondary operations successfully used in the process of manufacturing finished powder metallurgy parts.
Unlike parts manufactured using other metal forming processes, powder metallurgy parts can be pressed or cast, and can also be adjusted in size to densify or change the surface shape and provide more stringent dimensional control. Since the early 1920s, powder metallurgy self-lubricating bearing components have been impregnated with oil, and the components can absorb 12%-30% of the oil. Resin impregnation can also be performed on powder metallurgy parts to improve processability or prepare the surface for electroplating. Penetration is the second process step to increase strength or seal parts to make them airtight or liquid tight. Optionally, like resin impregnation, it can also be used to enhance processability, improve ductility and prepare parts for electroplating.
Processing powder metallurgy parts
With well-designed tools, good processing capabilities and compact CNC closed-loop control, most powder metallurgy (PM) parts processing may not be needed. In many cases, the tight tolerances of the mold and the tight control of powder selection (control of part size changes due to material selection) mean that the machining that may be required according to the application requirements is very easy to manage.
Having said that, due to the nature of PM as a net shape axial compaction process, there are processing features that cannot be formed in place, such as cross holes, undercuts, and threads. Using machining charts made for forged materials may lead to marginal results. In the past, the PM industry has made considerable efforts to solve this problem. The first is to understand the microstructure relationship between PM and processability, as well as processability characteristics, blending and pre-alloy additives, as well as "green processing" (non-processing non-processing). Machining) and other technologies. -Sintered PM real parts). Processing high-density PM parts (density> 92%) is similar to processing forged materials.
Depicts those variables that affect PM processing. Addressing these variables methodically at once will help optimize processing practices for a given material. As with all metals, the processing practices for a given material under given "conditions" will affect speed, feed, and tool selection. When considering PM processing, one of the key variables is the porosity (or density) of the part. The traditional method of improving machinability is to infiltrate the holes of the part with resin. This fills the pores and provides some lubrication, thereby preventing the tool from overheating and "chattering". Similarly, copper can be used to infiltrate parts and increase the strength of parts, but at an increased cost.
As found in the forging process, alloy additives such as manganese sulfide can improve the workability of the alloy. The widely used iron-copper PM alloys with and without MnS are compared. The use of MnS additives leads to a 25% reduction in drilling force and a 50% reduction in wear.