Meaning
Coordinate measuring machine probe distortion patterns quantify directional variation in trigger force when a tactile stylus contacts a measured surface. In mechanical metrology, stylus lobing represents the systematic triangular measurement error caused by internal spring forces within kinematic touch-trigger probes. The metric governs spatial measurement uncertainty during three-dimensional part inspection and ceases to apply when using optical sensors or continuous contact scanning probes.
Contact Geometry
Internal mechanical seats arrange three equidistant contact points around the internal pivot mechanism of touch probes. Bending moments vary depending on whether the contact force aligns with a support seat or falls between two supporting pins.
Error Characterization
Touch probe triggers generate a characteristic three-lobed error pattern when plotted across three hundred sixty degrees of contact angles. Evaluating stylus lobing involves measuring a certified reference sphere at multiple vector approach angles to construct an accurate error map. Calibration software compensates for these lobing errors by applying directional trigger offsets during part measurement cycles.
Uncompensated lobing introduces artificial surface form errors into inspection reports, compromising quality acceptance records.
Equipment Acceptance
Purchase agreements for high-accuracy coordinate measuring systems establish strict maximum limits for probe lobing errors. Equipment inspection protocols require verifying stylus lobing using standardized calibration routines before signing off on final machinery acceptance certificates.
