In achieving just-in-time, high-quality, and low-cost production, trigger probes offer far more support than simply aligning the workpiece; that is, directly inspecting the geometric accuracy of machined workpieces on the machine tool is equally valuable. This direct accuracy inspection can quickly detect programming errors, tool defects, and adverse consequences of the machining process. However, this inspection method is often not adopted because programming is considered too complex or there is a lack of confidence in the machine tool's accuracy. However, the basic accuracy of the machine tool is a crucial prerequisite for machining precision parts. Therefore, instruments such as laser interferometers should be used to periodically (recheck) the geometric parameters of the machine tool. Renishaw (www.renishaw.de) recommends the ML10 Gold Standard laser interferometer system for this purpose, and also periodically uses a QC10 circular measuring instrument. This subsequent measurement on the machine tool simultaneously creates conditions for process control. Measurements on a coordinate measuring machine (CMM) only indicate whether the machined workpiece meets requirements and cannot be used to distinguish the influence between the machine tool, cutting tools, and the machining process. If the machining deviation of the workpiece is measured, it is difficult to determine the actual cause of the deviation. Therefore, it is not possible to reliably derive appropriate or necessary corrective measures from the results of such measurement. Measurement tasks for machine tools There are basically four typical user requirements for measurement tasks for machine tools: (1) simply aligning the workpiece or measuring the tool; (2) some ancillary measurement tasks based on drawings, with the measurement cycle integrated into the program flow, controlling the machining based on the measurement results, and simply outputting the measurement results; (3) all measurement tasks are directly and completely integrated into the machining program, controlling the machining based on the measurement results, programming based on CAD data, performing collision checks through graphic simulation, and outputting the measurement results in tabular form; (4) inspecting the geometric accuracy of the workpiece after machining, programming based on CAD data, performing collision checks through graphic simulation, statistically analyzing and processing the measured values, and representing and analyzing the results in tabular and graphical form. For this purpose, Renishaw's measurement technology experts have provided several program packages designed for different requirements. If the user only wants to align the workpiece and measure the tool, then the widely popular control-oriented cyclic measurement program package should be used. This software package makes workpiece alignment and tool measurement very simple and convenient to program. It replaces simply verifying accuracy with controlling precision . At Renishaw, the Productivity software family allows for the easy creation of all measurement programs for milling machines, independent of the machine tool control system used, with the support of a graphical interface. During programming, the Active Editor and Active Editor Pro, along with additional CAD data input, are used to incorporate all workpiece and tool measurement programs into the machining program. These programs can then adjust the process through direct feedback from the measurement results. This not only corrects the machine tool's coordinate system and tool data but also, to some extent, automatically performs logical decisions based on this data, without requiring the identification of instructions needed for control. This simple and hierarchical rule structure also allows users to operate without using special NC instructions or having detailed knowledge of program structure. The user interface provides appropriate preset values ​​and checks whether all absolutely necessary inputs have been implemented. Only through the execution of the post-processor is the program and the instructions for the selected control generated. Therefore, when the machine tool machining plan changes suddenly, the parameters can be precisely adjusted as if in reverse. The Active Editor Pro version of CAD input not only further simplifies programming but also provides a complete representation of measurement motions, including measurement simulations such as collision checks. This simulation also takes into account clamping tools. Measurement and Recording Accuracy After machining, to directly inspect samples on the machine tool, especially complex or large workpieces, Renishaw collaborated with CAD/CAM experts at Delcam (www.delcam.de) in the UK to develop the Renishaw OMV software. By clicking on the features and surfaces of the input CAD workpiece model, the OMV software can generate the required measurement program. The Active Editor provides preset values ​​suitable for practical use and performs reliability tests during input. After data input, the program displays a graphical simulation of the measurement program, which undoubtedly increases the user's confidence in the accuracy of the measurement process. Using a highly accurate resistance strain gauge-based spindle—a trigger probe, such as the new compact OMP400 or the proven MP700 trigger probe—points on a surface are measured, and the measuring instrument transmits the data to a PC. Data analysis is performed using a specialized measurement calculation method similar to that of a coordinate measuring machine (CMM), thus allowing for the measurement of complex free-form surfaces. For this purpose, the MP700 and OMP400 trigger probes not only require calibration in all vector directions but also enable immediate measurement in all vector directions. This significantly improves cycle time, as each workpiece requires a small number of measurement points. Based on the CAD model, Renishaw's OMV software not only indicates the measured deviations but also represents these deviations using colored dots. These dots generate a color map that allows for rapid assessment of workpiece accuracy, providing numerous possibilities for statistical analysis and graphical representation of measurement results. A set of measurement points can be adapted to the CAD model (optimally satisfying functionality) to avoid errors during workpiece alignment and reference point selection. Therefore, the errors of a workpiece can be identified and corrected before it is removed from the machine tool. The ability to inspect the dimensional accuracy of workpieces under various processing conditions not only saves time but also increases confidence in the machining process.