In the design of the compaction process, the powder metallurgy gear will produce compact defects due to the analysis of various problems, which will lead to the scrap metallurgy parts in my country. So, what are the defects in the powder metallurgy gear compaction process?
1. The density of the green compact does not meet the design requirements
In the production of powder metallurgy gears, the higher the material density, the higher its physical and mechanical properties. In other words, the density and distribution of powder metallurgy gear components will determine the performance Chinese Powder Metal parts of the product. Therefore, in the debugging and pressing process of powder metallurgy gear molds, the density of a single box is an item that must be tested. In density testing, it should be noted that the different structures and requirements of the pressure blank should be treated differently.
2. The size of the round sample does not meet the requirements
Unqualified radial size or hole distance
2.1 There may be problems with mold design or manufacturing. If the error can be eliminated by adjusting the process (that is, by adjusting the powder composition, green compact density, sintering process, etc.). ). It can also be remedied, otherwise only the mold will be scrapped.
2.2 Different axial sizes are unqualified
For stepless cylindrical breast blanks, adjusting the powder, changing the pressure or extending the holding time, you can adjust and stabilize the axial size. For the step pressure blank, adjust the forming position of the combined die punch, the powder ratio of each station, the running speed of the floating die punch, etc., and the height of the step can be changed.
3. Out of tolerance of shape and position
The reasons for the out-of-poor straightness include: out-of-poor mold straightness, uneven green density distribution, uneven green wall thickness, and so on.
The reasons for an out-of-poor parallelism include: out-of-poor mold parallelism, uneven powder loading, and so on.
The reasons for the difference in coaxiality are: the precision of the mold is too low, the precision of the pressing tools and equipment is low, the mold installation does not meet the requirements, and the dressing is not uniform.
When the powder flow rate is appropriate, the mold accuracy meets the design requirements, and the compaction tooling and equipment accuracy meets the installation requirements, the geometric tolerance is mainly related to the density distribution of the green compact. When the compaction method is determined, the density distribution of the green compact is directly related to the powder filling effect .
4. Unqualified appearance
High roughness, excessive burr data, falling edges and corners, fraying and cracking are all common defects in the design of the green compact.