Sintered mechanical parts
Parts with varying thickness
It is more difficult to obtain homogeneous density in parts with varying thickness: for this reason it is necessary to use much more complex presses and tools.
Image 3 shows a typical item with varying thickness, before and after compaction.
Density in the different zones is determined by the compaction ratio initial thickness/ final thickness - in this case it is equal to 2.2.
It is clear that it is impossible to guarantee the same compression ratio in zones with different thickness, if punches for the thinner sections cannot move independently.
Generally it is necessary to split the lower (thinner section) punch when the thickness varies by more than 15%.
The number of possible splits (and so the number of different possible thicknesses) is obviously determined by the versatility (number of independent movements) of the press.