Copper and copper alloy P/M parts can be pressed and sintered to their final shape and size, usually with the desired surface finish and with no draft angles. They can also be sized to close tolerances by coining or repressing, thus eliminating much of the machining required when other metal forming procedures are used. They can be machined, plated and joined by brazing and some of the alloys can be heat treated to enhance their properties.
Using commercial automatic presses, copper and copper alloy P/M parts can be produced rapidly and accurately at an average rate of 1,000 parts per hour. Some very simple shapes have been produced on rotary compacting presses at rates as high as 63,000 parts per hour. Sizes can range from miniature parts smaller than the ball of a ball-point pen to bearings weighing over 100 pounds.
The physical and mechanical properties of copper and copper alloy P/M parts are comparable with those of cast and wrought copper-base materials of similar composition. However, the P/M process permits a flexibility that the other processes do not possess. Parts can be produced that vary in density from the low-density required for self-lubricating bearings or filters to almost the theoretical density of wrought parts.
P/M parts are produced with a minimum of raw material loss and greatly reduced processing wastes, resulting in a new approach toward lower overall costs. As a further advantage, there is no pollution of the environment in the production of P/M parts.
Some of the basic advantages of powder metallurgy are:
- Metal powders are high-purity materials
- Close dimensional tolerances can be maintained
- High-volume process with excellent reproducibility
- Quality control is inherent in the process
- Low labor input
- Machining is eliminated or reduced
- Scrap losses are eliminated or reduced
- Segregation is avoided
- Controllable porosity and density can be precisely controlled
- Combines immiscible metals
- Complex shapes can be produced