Why Sintering Is Where Quality Is Won or Lost in PM

Powder metallurgy has four stages: mixing, pressing, sintering, and post-processing. If you're evaluating a PM supplier's quality capabilities, pay the most attention to their sintering operation. Here's why.

What Sintering Actually Does

After pressing, you have a "green compact" — metal powder compressed into shape but with minimal structural integrity. Sintering heats this compact to just below melting temperature, causing the metal particles to bond through solid-state diffusion. The part transforms from a fragile blank into a structurally sound component with real mechanical properties.

The Three Quality Checkpoints

Quality-focused manufacturers monitor three critical parameters during sintering:

• Dimensional stability: Did the part hold its dimensions through the thermal cycle, or did it deform?
• Porosity reduction: Was the porosity brought within acceptable limits for the application's requirements?
• Target density: Did the finished part achieve the density needed for specified mechanical properties?

What to Look For in a Supplier

When auditing a PM supplier's sintering capabilities, check for:

• Modern sintering furnaces with precise temperature control
• Controlled atmosphere (hydrogen, nitrogen, or vacuum) to prevent oxidation
• Documented temperature profiles for each part number
• In-process density and dimensional checks
• Statistical process control (SPC) data on sintering outcomes

Without proper sintering, every downstream operation — machining, plating, heat treatment — is built on a weak foundation. Smart buyers know to audit this step first.