Powdered Metal Use In Automatic Transmissions

OK Transmission Techies, remember the old days when you disassembled a clutch pack or planetary gear set and sliced up your hands on a clutch pack housing, disc, or planetary carrier assembly?  Many of these components were stamped, cast or machined steel and commonly lacked the deburing and finishing processes needed in order to reduce process costs.  Well those days are diminishing…  Why?

Many transmission component manufacturing is going to a process called P/M (Powder Metallurgy).  This is a process where ferrous and non-ferrous metals and alloys are in a powdered form.  These powders are then fed into a die, and then pressed into shape.  The part is now ejected out and sent through a sintering furnace where the part is hardened.  Unless a resizing or finishing process is needed, basically you now have a net-shape or near net-shape part.  The first part is basically a duplicate of the last part…

What types of transmission parts are manufacturered with P/M?

  • Torque Converters
    • Turbine Hubs
    • Stators
    • One way clutches
  • Pump Systems
    • Gear Pumps
    • Gerotor Pumps
    • Vane pumps
  • Clutches
    • Clutch plates
    • One-way clutches
    • Clutch Hubs
  • Gears and Drive
    • Planetary Carrier and Gears
    • Drive & Driven Sprockets
    • Output Flange Hubs
  • Speed sensors (Alloy Portion)

Not to mention many other small parts that can be produced by P/M.

What are the advantages of P/M?

P/M is Versatile: The basic versatility of P/M is applied in numerous industries including automotive, business machines, electronics, small and major appliances, agricultural and garden equipment, hand and power tools, recreational vehicles and heavy truck. Thousands of different cost saving, reliable P/M designs now serve these industries in a wide range of engineering applications. 


Custom Made Compositions: Materials can be combined to produce specific properties not usually attainable by conventional ingot metallurgy. Dissimilar materials, metallics, non-metallics plus materials of widely different characteristics can be compacted into Parts which have specific and unique properties. The combining of materials through the use of P/M technology is limited only by research and experimentation. 
Precision Control:  The P/M Parts producer is able to control his product from the raw powder to the finished part. He can create the material and produce a finished product resulting in an end  product which can be suited to the demands of the application. The end user of P/M parts is assured of uniformity and optimum performance characteristics. 

Unique Physical Properties: Physical properties can be varied from low density filters and self lubricating bearings to high density structural parts with minimum porosity. Tensile strengths can be varied from low to high. Due to inherent porosity in P/M parts, self-lubrication is another property only attainable through P/M technology. Parts can be made self-lubricating. Gears and other parts made from P/M possess sound dampening characteristics which permit quieter operation.
Less Material Loss and Usage: There is very little raw material scrap or excess waste in the P/M process. With the elimination of further processing such as machining and finishing, parts can produced with little to no scrap. 

Reduced Machining and Finishing: The experienced P/M Parts producer can work closely with the customer to produce a design which requires little to no secondary processing and handling thus offering a cost savings to the customer.
Repeatability and Reproducibility: The first part is the same as the last. Since P/M Parts are compacted in precision dies, each subsequent part is a duplication of the previous part. Each step of the process from the powder to the end product can be controlled precisely resulting in parts which can equal to or in most cases maintain closer tolerances than other metalworking processes.
P/M Is An Energy Efficient Process: A detailed study showed the total energy required to produce a P/M part is often 25%-50% less of that required to produce the same part by machining it from wrought.   
Below is a comparison chart of P/M versus other similar processes (Click on Chart to View Full Size):


P/M components have become far more stable than in the past and is becoming more cost effective in automatic transmission production, and yet provides net-shape green parts.  No burrs, no contaminating flashings that block screens, ports and shift valves, pre chamfered, aids in lubrication to friction plates, pretty much a perfect part every time.  A leading manufacturer of P/M technology is Fansteel-AST.  When producing high volume parts, P/M is the best choice.

 If you have further questions regarding P/M, feel free to contact me.

– Jack Miller (Click to View Business Card)


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