LIMITATIONS OF POWDER METALLURGY
1. Powder metallurgy process is not economical for small-scale production.
2. The cost of tool and die of powder metallurgical set-up is relatively high.
3. The size of products as compared to casting is limited because of the requirement of large presses and expensive tools which would be required for compacting.
4. Metal powders are expensive and in some cases difficult to store without some deterioration.
5. Intricate or complex shapes produced by casting cannot be made by powder metallurgy because metallic powders lack the ability to flow to the extent of molten metals.
6. Articles made by powder metallurgy in most cases do not have as good physical properties as wrought or cast parts.
7. It may be difficult sometimes to obtain particular alloy powders.
8. Parts pressed from the top tend to be less dense at the bottom.
9. A completely deep structure cannot be produced through this process.
10. The process is not found economical for small-scale production.
11. It is not easy to convert brass, bronze and a numbers of steels into powdered form.
Source Introduction of Basic Manufacturing Processes and Workshop Technology by Rajender Singh.