What are the causes of cracking of powder metallurgy products?
Dec 10, 2022
What are the causes of cracking of powder metallurgy products?
The problem of cracks after powder metallurgy pressing has always been a headache in the powder metallurgy industry. It not only affects the mood of the production staff, but also slightly neglects. Many parts with cracks, cracks and fractures after powder metallurgy pressing are directly transferred to the next process, even shipped, which is irresponsible for customers. What are the reasons for the cracking of powder metallurgy products? The following is an analysis of Zhongwei Precision Editor:
powder metallurgy
Intergranular translocation
The adhesion between particles is mainly formed by plastic deformation and powder block movement at first. Under ideal conditions, the densification process is bidirectional, symmetrical and synchronous, and there is no edge displacement between particles The displacement movement after the densification process will prevent the formation of inter particle bond, and can destroy the bond that has been formed in the early stage of forming.
2. High tension, shear force
In the powder metallurgy embryo state, if the tension and shear force generated by external or internal factors are higher than the embryo strength of the shape itself, cracks will occur.
3. Wrong material integrity
For various reasons, metal powders use additives. For example, adding a suitable lubricant for mixing improves compressibility and reduces demoulding force However, adding too much lubricant to mixed iron powder will inhibit the formation of adhesion between particles, and adhesives, impurities and even residual air will have a negative effect on the formation of adhesion.
4. During abnormal plastic strain separation forming
Irrecoverable plastic deformation will occur to the particles. In addition, recoverable plastic deformation will also occur. After the final forming stage, the relevant pressure will reduce and eventually drop to zero during the demoulding process At the moment when the forming pressure is released, the compressive stress is released, and the preform will suddenly change from plastic to elastic stage. If the internal stress is greater than the strength limit of the preform, cracks will occur.
The above is the introduction of the main reasons for the cracking of powder metallurgy products. Now do you know? Of course, there are some minor defects in powder metallurgy technology, but this does not affect the current important position of powder metallurgy in industrial production. Any technology has minor defects, but we should look at the good side. Don't focus on the trivial problems. At present, powder metallurgy technology is widely used in the field of home appliances, automobiles, medical equipment, digital electronics, etc, Powder metallurgy technology has higher cost performance ratio and more stable quality.
