There’s a tendency to put self-lubricating bearings in their own applications spotlight. Alternatively, given the chance, curious would-be engineers should try giving other powdered metal parts their chance to shine. Granted, bearing technology owes a lot to powder metallurgy, but there is a whole other range of equally capable powder-fabricated products, all of which use their porous structures to good effect. Filtration systems are one popular example, then there are powdered and sintered gears, plus many more examples.
Classifying Powdered Metal Parts
Strictly speaking, powdered metal parts are made out of mountains of atomized material. At least that’s how the process begins. Then, acting as the pressing and bonding force, the sintering stage shapes the discrete particles into a solid form. Of benefit to rotating shafts, low maintenance bushings and bearings are produced when the powder is mixed with a lubricating agent. Porous by design, the end product “sweats” slippery oil. Again, this is the application that most trainee engineers think about when they first get involved with powder metallurgy. Shifting gear, let’s push way beyond this key application base. Let’s see some other examples of powdered metal parts, ones that rely on this specialized fabrication method.
The Benefits of Controlled Porosity
Solid filtration components employ this principle when challenging, tortuous environments demand precise fluid sieving mechanisms. Made of a toughened metal, the filters channel high-pressure, high-temperature fluid loads in oil refineries and chemical processing plants. Mounted in a caustic processing line, a corrosive atmosphere can’t damage a porous chunk of metal. Likewise, pressurized hydraulic and pneumatic systems employ metals and glasses, ceramics and engineering plastics. All of those pressure retaining materials expand and compress at different rates, unfortunately. It’s tough to fit a metal cap or seal that can expand at a similar rate. Using a similarly specified PM produced component, the powder metal part is imbued with a low coefficient of thermal expansion, so its expansion rate mirrors the cylindrical valve it’s sealing.
In the first generation of sintered products, self-lubricating bearings took flight. Bushings conquered maintenance problems and oil-feed issues. Then came filtration solutions, intricately shaped gears, and more. Now there are powder metal parts that satisfy hundreds of different usages. Carriage bushings move on rails while delivering that same ever-handy self-lubricating feature. Then there are magnetically charged powdered components, which add exotic powders to the mix. Just by altering compaction pressure and sintering temperature, the magnetic strength of a geometrically sophisticated component is easy to manipulate. This feature, now popular in the automotive industry, is opening new avenues for the powder metallurgical sector.