Calibration of an interferometric on-machine probing system on an ultra-precision turning machine

Abstract

Surface measurement is fundamental to further enhance accuracy and efficiency in ultra-precision machining. Advanced on-machine measurement (OMM) is evolving as the key enabling technology for autonomous and intelligent manufacturing. The present work integrates an interferometric probing system on an ultra-precision turning machine. However, due to relatively harsh environment in the machine tools, metrology characteristics of surface measuring instrument would deviate from those tested in laboratories. In order to improve the performance of on-machine measurement system, it is necessary to calibrate the OMM system and compensate the systematic errors. Three major error sources, including on-machine vibration, machine tool kinematic errors, and linearity errors are investigated according to the characteristics of interferometric single point OMM. For on-machine vibration, a theoretical study of the relationship between sampling frequency, scanning parameters, vibration frequency and topography frequencies of interest is first presented. Static and scanning vibration tests are performed in order to select the proper sampling frequency. Machine scanning error is mapped for OMM correction with the proposed kinematic error modelling measurement and compensation method. Calibration of the response curve and linearity error correction is conducted by measuring a radially distributed step height sample on the machine. Experimental investigation is conducted which proves the validity of proposed calibration methodology and the effectiveness of OMM. After the calibration process, OMM results agree well with calibrated offline measurements.

Development and Application of Interferometric On-Machine Surface Measurement for Ultraprecision Turning Process

“…More OMSM experiment results has been presented in authors' previous work [28,29], which indicate that the established OMSM has comparable measurement accuracy with commercial offline measurement in terms of form evaluation.…”

“…Due to mechanical imperfections, wear of machine tool elements, and stage misalignments, the deviation from the programmed scanning path (known as kinematics error) will induce additional measurement errors. The above issues has been addressed in detail in the authors' previous work [28,29].…”

On-machine and in-process surface metrology for precision manufacturing

“…Compared with on-machine full-field measurement systems, on-machine probe-scan systems are more flexible in terms of measurable shapes and sizes of workpiece. However, in addition to vibration, the mounting/alignment errors of the probe as well as the error motions of the machine axes have to be taken into account as the major sources of measurement uncertainty [146]. Thermal drift of the probe output and thermal expansion of the workpiece and the machine tool are also uncertainty sources due to the time-consuming scan operation.…”

Measurement of Freeform Optical Surfaces: Trade‐Off between Accuracy and Dynamic Range

“…As a result, the surface error “copied” from the motion error is not detectable through the probe with the same motion error. Therefore, calibration [ 195,196 ] or separation [ 197,198 ] of the motion error is indispensable. The on‐machine measurement is thus significantly different from the off‐machine measurement as shown in Figure a.…”