With developments in computer science and technology, microelectronics, precision engineering, and micromechanics, many engineering parts with small sizes and tight tolerances must be measured with high accuracy to ensure their engineering functional requirements. This includes one-, two-, and, three-dimensional measurements ranging in size from micrometers to 1 mm, combined with the measurements of curves, angles, geometric form, and position errors, as well as surface roughness and waviness.

By profiling methods such as contacting stylus techniques or by area profiling methods such as phase-shift interference microscopy, confocal microscopy, or a rastered stylus technique, combined with different surface sampling intervals, profile separation techniques, and algorithms.

The

Figure 1.  Rockwell indenter.

Figure 2.  A stylus instrument and x-y rotary stage.

A stylus instrument and an x­y rotary stage (see Figure 2), combined with NIST designed calibration and check standards, calibration and uncertainty procedures, algorithms, and software, are used for this purpose. The expanded measurement uncertainties are ± 0.4 micrometers for the 200 micrometers tip radius, and ± 0.01 degrees for the 120-degree cone angle calibrations. Meanwhile, profile deviations from the least-squares radius, cone flank straightness, holder axis alignment error, and surface roughness can also be measured.

The NIST has the highest accuracy microform calibrations for Rockwell diamond indenters in the world. Indenters calibrated here are used in the NIST Rockwell Hardness calibration facility in the Materials Science and Engineering Laboratory. Under a new project, NIST and several other national laboratories are teaming up to establish a worldwide unified Rockwell hardness scale based on precisely calibrated standard grade Rockwell diamond indenters.