What Are The Defects In The Powder Metallurgy Compacting Process?

1. The compact density does not meet the design requirements

In the production of powder metallurgy parts, the higher the density of the material, the higher the physical and mechanical properties. That is to say, the density and distribution of the compact density of the powder metallurgical parts will determine the performance of the final product. Therefore, in the powder metallurgy mold debugging and pressing process, the density of the green compact is a project that must be detected. In the density detection, it should be noted that different structures and required compacts should be treated differently.

2, The compact size does not meet the requirements

2.1 Unqualified radial dimension or unacceptable hole pitch

There may be problems with mold design or manufacturing. If the error can be eliminated by adjusting the process (ie by adjusting the powder composition, compact density, sintering process, etc.). It can also be remedied, otherwise only scrap molds will be scrapped.

2.2 Axial size is unqualified

For stepless cylindrical compacts, adjust the powder size, change the pressing pressure or extend the holding time, etc., and adjust and stabilize the axial dimension. For the step press blank, the step height dimension can be changed by adjusting the forming position of the combined die punch, the powder loading ratio of each stage, and the running speed of the floating die punch.

3, The geometric tolerance is out of tolerance

3.1 Straightness

The reasons for the straightness difference are: the straightness of the mold is excessive, the density distribution of the compact is not uniform, and the wall thickness of the compact is not uniform.

3.2 Parallelism

The reasons for the parallelism are: the parallelism of the mold is too poor, and the powder is uneven.

3.3 Coaxiality

The reasons for the difference in coaxiality are: the accuracy of the mold is too poor, the precision of the pressing tooling and equipment is low, the mold installation does not meet the requirements, and the dressing is uneven.

When the powder flow rate is appropriate, the mold precision meets the design requirements, the pressing tooling and the equipment precision meet the installation requirements, the shape tolerance is mainly related to the density distribution of the compact. In the case where the pressing method is determined, the density distribution of the compact is directly related to It is related to the effect of filling powder.

4, The appearance is unqualified

High roughness, excessive burrs, falling corners, napped and cracks are common defects in the appearance of compacts