Advanced Technologies

Sintered Metals

Sintered Metals – Aluminum Sintering

Sintering is the process of forming a solid mass of material with pressure and heat without melting. The pressure and heat can be applied at the same time ( through Hot Isostatic Pressing, or HIP) or in multiple steps. The HIP process is usually used for simple shapes and low quantities while the multi-step process is used for complicated products and large quantities. In either case the process begins with pSintered Aluminum Partsrecisely controlled powders. The multi-step process requires that the powder be mixed with an organic binder and lubricants then pressed into a shape that is slightly larger than desired. The final size of the part is a combination of the density

of the pressed part and shrinkage during sintering. The pressing can be done in numerous ways, but the most common is die pressing. The firing process requires that the binder and lubricants be removed before the parts are heated to just below the liquidus where they sinter or densify. After the binder has been removed the metal particles begin to attach to each other through surface diffusion. Next, the attachment points begin to grow as the surface diffusion increases – sometimes called necking. There is no decrease in the distance between particle centers. Finally, the part shrinks as the porosity diminishes and the distance between the particle centers become smaller – densification

Continuous belt furnaces are the best solution for high production volumes because of their exceptional uniformity, and excellent process repeatability. Minimizing the oxidation of the aluminum is accomplished by using nitrogen to ensure that there are low O2 and moisture levels.

Precision Controlled Belt FurnaceProcess Requirements for Inline Aluminum Sintering

  • Dry Nitrogen
    • < 10 ppm O2
    • < 50 ºC dew point
  • Peak Temperature capability of < 650 ºC
  • Atmosphere separation between the binder burn out and sintering section of the furnace to ensure good sintering.
    • A method to dispose of binder after removal
  • Ability to produce acceptable profiles
    • Peak temperature, ramp rates and soak time
    • Zone configuration
  • High power and enhanced cooling for heavy product loads
  • Product clearance, width, and throughput

BTU Controlled Atmosphere Muffle Furnaces (TCA) are optimized for aluminum sintering. The furnaces are fully customizable to meet varying process/production requirements. Key features include:

  • Muffle construction for high purity N2/H2 atmosphere operationEductor for convection heating or cooling
    • <2ppm O2 Inert atmosphere
    • National Fire Protection Association NFPA 86, NFPA-79 and UL508a safe atmosphere compliant
    • Made in the USA with high quality materials for maximum reliability
  • Left Center Right TrimImproves part uniformity and yield
    • Uniform eutectic across plates
  • Gas Barrier*
    • Superior atmosphere separation
    • <2ppm O2 Inert atmosphere
  • Cooling Eductors*
    • Shorter foot prints
    • Controlled cooling of heavy loads

*May only be required for most demanding applications based on load/profile