Powders for Metal Injection Molding

Metal Injection Molding offers diversity: Stainless steels to titanium and superalloys

In Metal Injection Molding, particle size distribution is the most important powder characteristic as this determines the sinterability and surface quality of the final product. As a general rule, the finer the powder the better.

 

Carbonyl iron and nickel powders

Fortunately for Metal Injection Molding technology, very fine carbonyl iron and nickel powders were already in industrial production when the process was developed.

Powders for Metal Injection Moulding - Carbonyl

Fig. 4 Carbonyl iron powder (SEM, top, with scale showing 5μm) and cross-section of a particle (Courtesy BASF, Germany)

These powders have spherical particles, which is beneficial for good flowability, with particle sizes of less than 10 µm, an order of magnitude finer than the common atomised and reduced iron powders used in uniaxial powder compaction (Fig. 4).

Carbonyl iron powder has excellent sintering properties. The small particle size provides a high sintered density, excellent strength and surface texture quality in the final part. The uniform spherical particle shape gives high dimensional accuracy.

Many ferrous MIM alloys are based on carbonyl iron and nickel. Powders are mixed with elemental or master alloy powders to achieve the desired alloy composition.

 

Powders for Metal Injection Moulding - gas_atomised_powder_Osprey

Fig. 5 Gas atomised 90% 16 μm 17-4PH metal powder produced by Sandvik Osprey, UK

Water and gas atomised powders

Prealloyed powders are predominantly (but not exclusively) used for high alloy steels, nickel and cobalt base alloys. Alloy powders are usually gas atomised and have a spherical particle shape.

In some cases, water atomised powders with irregular particle shapes are also added.

With the growing demand for fine metal powders, manufacturers have improved their atomising techniques. Today, specialists offer many kinds of high alloy steel powders with less than 10 µm average particle size.

There are a number of well established companies supplying atomised powders for Metal Injection Molding, including producers in Europe, North America and Asia.

> Next page: Binders and Binder Removal Techniques

 

Industry News

Read the latest issue of PIM International

The latest issue of PIM International magazine is available to view online or download in PDF format.

As well as an extensive MIM, CIM industry and sinter-based AM industry news section, this 124-page issue includes the following exclusive articles and reports:

  • Bosch Advanced Ceramics: Driving ceramic Additive Manufacturing for series production with Lithoz
  • High precision, flexibility and intensive customer support: How Demcon MIM is planning ahead for long-term growth
  • Playing the long game: The story of Binder Jetting, and ExOne’s view on a rapidly evolving technology landscape
  • Riding the storm: A review of progress in China and Taiwan’s MIM industry during 2020
  • Advanced Powder Injection Moulding process developments presented at Euro PM2020
  • > Go to magazine page

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