Coining or Cold Deformation
A sintered part is forced to conform to a rigid mandrel or substrate and in doing so the body is slightly deformed to match the substrate. This provides additional control for dimensional tolerances. Coining is also used to improve flatness.
All common machining operations can be applied to MIM components. Machining is often performed to add threads, undercuts, grooves, or other special features that would be difficult or expensive to accommodate in the tooling.
MIM components utilize the same heat treatment operations as their wrought counterparts to increase material properties, such as quench and tempering. In some cases, heat treatment is included within the cooling cycle or by use of a properly designed post-sintering cycle.
Hot Isostatic Pressing
Hot isostatic pressing is a process that utilizes elevated temperature and isostatic gas pressure to eliminate non-surface-connected porosity and increase density in metals. In most cases this increases the part to 100% of theoretical density and imparts the associated improved mechanical improvements accordingly. This improves the material’s mechanical properties and, potentially, workability.
Carbon is important to attaining high strengths in steels. A high surface hardness is attained with carbon surface additions using a heating cycle with an atmosphere containing a high carbon potential.
Like other metallic components, MIM components are joined by welding, brazing, or even adhesive techniques.
Surface treatments such as polishing, coating, painting, cleaning, anodizing, plating, sealing, and laser glazing can all be applied to MIM components.