Inertia compensation while scanning screw threads on coordinate-measuring machines

Usage of scanning coordinate-measuring machines for inspection of screw threads has become a common practice nowadays. Compared to touch trigger probing, scanning capabilities allow to speed up measuring process while still maintaining high accuracy. However, in some cases accuracy drasticaly depends on the scanning speed. In this paper a compensation method is proposed allowing to reduce the influence of some dynamic effects while scanning screw threads on coordinate-measuring machines

New advances in traceability of CMMs for almost the entire range of industrial dimensional metrology needs

The paper reports on results of the European project EASYTRAC. The first main goal of this project was to significantly reduce the efforts associated with the traceability of industrial dimensional metrology laboratories by means of the almost exclusive use of coordinate measuring machines (CMMs) in combination with laser interferometers. The second main goal was to develop and validate CMM-specific methods for task-related measurement uncertainty analysis. In this paper, significant achievements from the EASYTRAC project are reported, with particular emphasis on : i) error compensation using reversal techniques; ii) use of laser interferometers on CMMs to reduce measuring uncertainty when calibrating standards of length; iii) development of other task-specific calibration techniques; and iv) use of multiple measurements strategies for uncertainty assessment. Uncertainty analyses of virtually any measurable feature were performed and validated, including freeform, gear and thread parameters. This work has provided an extensive experimental basis for the elaboration of the ISO/TS 15530 series of standards