PM Process - Overview

The basic PM process can be broken down into four sequential steps:

Blending

Compaction

Sintering

Coining

Blending (brief)

• PM alloys are pre-mixed in the powdered state using mechanical blenders
  
• Highly specialized blenders are utilized to create and homogenize that mix.
  
• The blends used at Sterling Sintered are usually made in 5,000 to 20,000 pound batches.
  
• Blending can often happen such that thousands to millions of parts can be made from a single batch.
  
• Click here for a more detailed description of blending.
  
• Click to see the process controls utilized at Sterling Sintered during blending.
  

Compaction (brief)

• Compaction of PM parts happen under very high pressures.
  
• Compaction pressures of 80,000 psi are not uncommon.
  
• Powder flows downward into the mold die from the feed shoe using gravity.
  
• A compaction punch enters the die, sealing it off from above.
  
• That top punch in conjunction with punch(s) from below compact the powder in the die increasing the powder density as they do.
  
• The top punch retracts
  
• The bottom punch pushes the part out of the die.
  
• Many times, the part shape dictates the use of multiple punches and motions during compaction.
  
• Sterling Sintered has many compacting presses with multiple motions ranging from 4 to 110 Ton capacity.
  
• See our case study page for examples of part designs.
  
• Click here (link) for a more detailed description of Compaction.
  
• Click to see the process controls utilized at Sterling Sintered during compaction.
  

Sintering (brief)

• Sintering of PM parts happens at elevated temperatures.
  
• The parts are heated to a hot enough temperature that the metals weld together.
  
• Also, elemental ingredients diffuse and the final alloy is created.
  
• A reducing atmosphere consisting of Hydrogen and Nitrogen is used to protect the metals.
  
• Next the parts are cooled down to room temperature.
  
• Specialized Sintering can occur at Sterling Sintered to accomplish specific effects.
  
• Copper infiltration can increase a steel part’s strength significantly.
  
• Varying the protective atmosphere can also affect certain mechanical properties.
  
• Sterling Sintered can vary that atmosphere all the way from 100% Hydrogen to
  100% Nitrogen to swing those properties. Most of our competition is locked in at one ratio.
  
• We can also vary the cooling rates such that some steel materials can land in the
  Rockwell C scale without post-process Heat Treatment!
  
• Click here (link) for a more detailed description of Sintering.
  
• Click to see the process controls utilized at Sterling Sintered during sintering.

Coining (brief)

• Where needed (less than 10% of the time) Coining and Sizing operations
  are used to reduce dimensional variation and/or improve part properties.
  
• Let the Sterling Sintered engineering department help you balance product requirements and cost.
  
• Click here (link) for a more detailed description of Coining.
  
• Click to see the process controls utilized at Sterling Sintered during coining.
  

Other Secondaries

• Nearly any secondary operation that can be performed to a wrought part
  can be performed on a mechanical component made by PM technology.
  
• Click here for more details on secondary operations available at Sterling Sintered Technology.
  
• Click to see the process controls utilized at Sterling Sintered during Secondary Oprns.

If you have any questions on the PM process, give us a call. We are available to discuss your PM needs M-F, 9-5 GMT-5, at 860-379-2753.