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Densification
 Density is the key parameter which largely determines the performance of powder metallurgy components. Density is defined as mass per unit volume, and is typically stated in terms of grams per cubic centimeter (g/cm3). For wrought materials, density is nearly a constant. For powder metal materials, however, a given alloy system can be produced in several density ranges.
Several properties of powder metal materials are directly affected by density. These include: - Electrical/Thermal Conductivity
- Magnetic Permeability
- Saturation Induction
- Ultimate Tensile & Yield Strength
- Fatigue Strength
- Rupture Elongation
- Apparent (Macro) Hardness
- Modulus of Elasticity
- Poisson's Ratio
- Surface Roughness
- Hardenability
Conversely, the following properties are not affected by density: - Coefficient of Thermal Expansion
- Thermal Capacity of the Mass
- Melting Temperature
- Temperature of Microstructural Transformations
- Particle (Micro) Hardness
Precision Cold Forming There are a number of processes that, when properly executed, can improve the density of powder metal parts. One of these is Precision Cold Forming, or PCF. Developed by Metal Powder Products Company, Precision Cold Forming is an innovative technical breakthrough. PCF technology produces gears and other components that exhibit excellent endurance and superior wear characteristics. PCF combines several technologies to produce components such as gears with powder metallurgy economics and cut wrought gear performance. Typically, as can be seen in the chart at the top of this page, increasing performance results in ever-increasing costs. PCF offers the design engineer the ability to obtain enhanced performance and improved economics. MPP has used the PCF process to develop products such as bevel gears used in high-performance garden tractor applications to replace cut steel gears. Static and dynamic test results have been extremely positive, and PCF has proven to provide better fatigue properties. In a series of accelerated life, test track, and flywheel inertia tests, the PCF gears exceeded test goals by 10% to 200% with only minimal wear. Other potential applications for this technology include demanding applications such as truck and automotive differentials, PTOs, and similar right-angle gearboxes used for the transfer of motion.
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