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Precision metrology, like other machine tool technology, has found a way to deal with complex parts more accurately. Multi-sensor machines use two or three synchronized instruments in one machine to gage, measure, and inspect a part.
The combination is usually the result of adding sensors to an existing platform designed around a sensor, according to Fred Mason, marketing communications manager, Optical Gaging Products. "The most common examples are video measuring machines to which laser and/or touch probe sensors are added, and CMMs (touch probe) to which a video sensor is added," Mason says. While laser, video, and touch probe are the most commonly used sensors, new entries like infrared technologies are making their mark.
Each sensor can bring a degree of uncertainty to the measurement accuracy, requiring the strictest calibration. But the machines do have their advantages. "The more properly synchronized sensors that exist on a system, the less changes have to be made for measurements of features on a part," explains J. Orlando Vera, product manager, multi-sensor products, Mahr Federal Inc. "This in turn minimizes repositioning errors as well as handling errors."
Value comes from combining functions on one machine, eliminating the need for multiple units and different types of software. Although multi-sensor measurement is not a new idea, many companies are adding features that make the process more efficient.
Once measurements are taken with the sensors, software takes over. "Keeping track of all the measurement data points from multiple sensors as the part is rotated in more than one axis is the job of the software. Tight integration of sensors into the software ensures the necessary accuracy," OGP's Mason says. "The best implementations incorporate all sensor data into a common part analysis, not as separate, independent capabilities," says Mason.
Software is at the heart of Mahr Federal's approach to multi-sensor measurement. The newest option on the Multiscope 222 is the CAD interface that allows the user to import a CAD model and measure directly from the CAD model, rather than a manufactured part. The machine's software supports CAD import/export, DMIS interfacing, real-time statistical analysis, 2D profile scanning, and 3D profile analysis export.
Brown & Sharpe multi-sensors use PC-DMIS, among other types of...