PM Process - Overview

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

Blending

Compaction

Sintering

Coining

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 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 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.

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.

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.