Case Study: Enclosed Striker

Process: Metal injection molding (MIM)

Material: S7 tool steel

Density: 7.5 g/cm³ 

Tensile Strength: 1,850 MPa (268,000 psi)

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End Use and Function

The enclosed striker is integral to the firing mechanism of a commercial grade pistol. It is sold by a global manufacturer of striker-fired handguns that serve both law enforcement and civilians.

Fabrication

The enclosed striker is made in a 2-cavity mold. Strategic tool design and staging was implemented to mitigate differential shrinkage out of sintering, which often occurs with long, thin geometries. The additional upfront engineering was rewarded, as the ideal staging method was identified, eliminating a sizing operation. Post-sintering, hot isostatic pressing (HIP), and heat treatment are performed to increase mechanical properties. The parts are
made using S7 tool steel powder processed to a 7.5 g/cm³ density and a tensile strength of 1,850 MPa (268,000 psi). A two-stage grinding process
is required to achieve the 0.1 mm (0.004 in.) tip position specification. The grinding process includes machining the two main datum diameters on the body and the functioning tip of the striker. The position of the tip to the primary body of the component is critical for part functionality. The parts are finished with an electroless nickel coating.

Results

The enclosed striker was designed for the MIM technology, allowing for a near-net-shape part directly out of the mold. The specific alloy and
HIP process were selected to ensure the component’s resistance to wear—essential for the function of the striker.