The growth of the P/M industry during the past few decades is largely attributable to the cost savings associated with net (or near-net) shape processing compared to other metalworking methods, such as casting or forging. In some cases, the conversion of a cast or wrought component to powder metal provides a cost savings of 40% or higher.
PM typically uses more than 97% of the starting raw material in the finished part and is specially suited to high volume components production requirements.
There are two principal reasons for using a powder metallurgy product:
- cost savings compared with alternative processes, and
- unique properties attainable only by the PM route
In the automotive sector, which consumes about 80% of structural PM part production, the reason for choosing PM is, in the majority of cases, an economic one.
PM process enables products to be made that are capable of absorbing up to 35% of selected fluids.
Why then is PM more cost effective?
Better material utilisation with close dimensional tolerances. Conventional metal forming or shaping processes, against which PM competes, generally involve significant machining operations from bar stock or from forged or cast blanks.
These machining operations can be costly and are wasteful of material and energy.This is illustrated in the figure below which shows that material utilisation in excess of 95% can be achieved with close dimensional tolerances.
Raw material utilisation and energy requirements of various manufacturing processes.
This is a comparison between various manufacturing processes (Casting, Cold or Warm Extrusion, Hot Drop Forging, and Machining Processes) and PM sintering for a production of notch segments for truck transmission.
The PM process has:
- the highest raw material utilisation (over 95%)
- and the lowest energy requirement per Kg of finished part
- comparing with the other manufacturing processes
The energy savings alone contribute significantly to the economic advantage offered by PM..
An example is given below for a notch segment used in a truck transmission, where PM consumes only around 43% of the energy compared with forging and machining and the number of process steps has been greatly reduced. .
Comparison of the PM Process and Forging and Machining (energy requirements and number of process steps)
This is an example for a notch segment used in a truck transmission, where:
- PM consumes only around 43% of the energy compared with forging and machining, and
- the number of process steps has been greatly reduced
Forging and machining :
Cost Comparison between PM and Forging: