In the realization of punctual, high quality and low cost production, the trigger probe can provide more support than just looking for the positive workpiece. That is to say, it is also of great value to directly examine the geometric accuracy of the machined workpiece on the machining tool. Because through this direct accuracy test, we can quickly detect programming errors and tool defects, as well as the adverse consequences of processing. However, such testing methods are often not used because people feel that the programming process is too complex, or the accuracy of machine tools is not reliable. However, the basic accuracy of machine tools is an important prerequisite for machining precision parts. Therefore, we should use the instrument such as laser interferometer to check the geometric parameters of machine tools periodically. For this kind of measure, Renishaw Company recommends the use of laser interferometer system - ML10GoldStandard. In addition, the QC10 circular measuring instrument should be used regularly for inspection. In this way, the subsequent measurement on the machine tool also creates conditions for process control. The measurement on the three coordinate measuring instruments only indicates whether the processed workpiece is in conformity with the requirements and cannot be used to distinguish the effects between the machine tool, the tool and the process. If the machining deviation of the workpiece is measured, it is difficult to get the actual cause of the deviation. Therefore, the appropriate or necessary corrective measures cannot be reliably obtained from the results of this measurement.、

Measurement task for machine tools

There are basically 4 typical user requirements for measuring tasks in machine tools:

（1） It is only the alignment of the workpiece or the measurement of the tool.

（2） Inspect some incidental measurement tasks based on the drawings, the measurement cycle is integrated in the program flow, and the processing is controlled according to the results of the measurement, and the results of the measurement are simply output.

（3） All the measurement tasks are integrated into the processing program directly and completely, and the processing is controlled according to the results of the measurement. According to the CAD data programming, the collision test is carried out by graphic simulation, and the results are output in tabular way.

（4）  After processing, the geometric accuracy of the workpiece is tested, the CAD data is programmed, the collision test is carried out through graphic simulation, and the measured values are counted, analyzed and processed, and the results are expressed and analyzed in form and graphic mode

To this end, Renishaw's measuring technical experts provide several packages designed for different requirements, and if the user just wants to find a positive workpiece and a measuring tool, then a widely popular cycle measurement package for control should be used. With this package, the workpiece alignment and tool measurement can be programmed simply and conveniently.

Replacing inspection precision with control precision

At Renishaw, through the software family, Productivity can easily program the measurement program for milling machine under the support of graphics interaction , without not relying on the machining tool own control system. In programming, all workpiece measurement programs and tool measurement programs are incorporated into the processing program through the input of ActiveEditor and ActiveEditorPro together with additional CAD data, as a result, these procedures can achieve process adjustment through direct feedback from measurement results. This can not only modify the coordinate system of the machine tool and the data of the tool, but also automatically realize the logical choice to some extent according to the data, without the need to identify the instructions required for the control. In this way, this simple and hierarchical rule structure also enables users not to use some special NC instructions and not to have detailed knowledge of program structure. To do this, the action interface provides appropriate predetermined values and checks to see if all absolutely necessary inputs are implemented.  The program and instructions for the selected control are generated only by running the postprocessor. Therefore, when the machine tool processing plan changes suddenly, the parameters can be adjusted exactly like reverse conversion. The CAD input ActiveEditorPro version not only simplifies programming further, but also fully represents measurement movements and measurement simulations, including collision testing, which also takes into account clamping tools.

Accuracy of measurement and recording

After the machining, in order to test the workpiece directly on the machine tool and test the complex or large workpieces, Renishaw company co developed the RenishawOMV software with the CAD/CAM experts of the British Delcam company. By clicking on the features and surfaces of the CAD artifact model input, the OMV software can generate the required measurement program, such as ActiveEditor providing a predetermined value suitable for use, and testing the credibility of the input at the input.

After data input, the program shows a graphic simulation of the measurement program, which undoubtedly increases the user's trust in the accuracy of the measurement process. Using a highly accurate principal axis based on the resistance strain gauge in all measurement directions -- the trigger probe, such as the new compact OMP400, or the proven MP700 trigger probe, to measure the point on the surface, and the transmits the data to the PC.

The analysis and processing of data is accomplished by a special measurement and calculation method, which is similar to the measurement and calculation method of the tri-coordinate measuring instrument, therefore, it can also be used to measure the complex free surface. For this reason, the trigger gauges MP700 and OMP400 not only need to be calibrated in all vector directions, but also can be measured immediately in all vector directions. This also significantly improves the cycle time, since each artifact must have a small number of measurement points.

According to the CAD model, the OMV software of Renishaw not only indicates the deviation measured, but also uses color points to show the deviation value. These points produce a color map that can quickly judge the accuracy of the workpiece, which provides a number of possibilities for statistical analysis and the graphical representation of the measurement results. A set of measurement points can be adapted to the CAD model (optimal satisfying function), so as to avoid errors when the workpiece is aligned and determined datum point. Therefore, before the workpiece is removed from the machine tool, its error can be identified and corrected. The possibility of checking the dimension precision of the workpiece under various machining conditions not only saves time, but also increases the trust of machining.