Dimensional Tolerances

As a starting basis, MIM is capable of as-sintered tolerances of +/-0.3% of nominal (i.e. 1.000” +/-.003”). The exact tolerance capability on any feature is influenced by a variety of variables that are inherent in the MIM process.

  • The resulting tolerance capability may be less than the +/-0.3% noted above or greater in some cases
  • Variables such as part design, size, shape, material, gate location, number of cavities, mold construction techniques, annual part volume, and inspection techniques need to be taken into consideration
  • The material chemistry selected for your application can have a greater effect on tolerances than you might imagine
  • Not all materials produce the same tolerance results. Gauging or inspection requirements are an integral element of a component design and can have a heavy influence on tolerance capabilities
  • It has been our experience that theoretical intersections, centers of radii, and very small features require larger percentage tolerances due to gauge resolution, repeatability, and capability limitations. Our engineers are available to discuss gauging designs while assisting your component design efforts
  • Depending on component geometry, flatness and straightness specifications of down to .001 inch-per-inch are achievable
  • This is especially true if the entire critical surface can be supported during debinding and sintering, or the critical feature is perpendicular to the supported surface
  • Gate location, cross-sectional thickness, and cross-sectional geometry have an effect on the resulting straightness or flatness

Secondary operations

To minimize the cost of secondary operations, the general tolerance guidelines should be applied: 

  • Should a feature require a tighter tolerance than the MIM process can offer, a secondary metalworking operation can be performed
  • Our MIM material can be machined, tapped, drilled, broached, sized, ground, or welded like its wrought material counter-part
  • When annual volume requirements are high enough, we develop fully automated secondary operations to minimize the part cost of these added process steps

Feature Best possible + / - Typical + / -
Density 1% 1.5%
Weight 0.4% 0.40%
Linear Dimension 0.3% 0.5%
Tightest Linear Tolerance             0.03 mm 0.05 mm
Hole Diameter 0.3% 0.5%
Tightest Hole Tolerance             0.015 mm  0.05 mm
Average surface roughness 0.3 µm 0.8 µm

Source: MIMA Standards


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Last updated 11.27.2019