When measuring any mechanical artifact, thickness measurements obtained using a coordinate measuring machine (CMM) are affected by geometric variations having different wavelengths, leading to uncertainty in the reported thickness. These effects can be very pronounced in cast iron products, as the surfaces can be quite rough. This paper presents a methodology for reducing the uncertainty in the thickness measurements by comparing the measurements obtained using profilometry with CMM measurements. The surface data obtained from a profilometer are filtered using standard ISO filter and also using a morphological filter. The different wavelength components — such as the waviness profile and roughness profile — are separated and the thickness values are obtained from the filtered and unfiltered surface profile. The efficacy of different filtering methods is examined, and a procedure for reducing the uncertainty of the reported thicknesses is proposed.

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