Advantages of a Multi-Sensor CMM
When one is just not enough!
All is right with the world: the CMM is merrily beeping away inspecting parts to its heart's content. What could be wrong with this? This is the perfect device for measuring everything; or is it? The CMM itself is a three-axis, high accuracy, positioning device. What transforms this mechanical entity into a measuring machine is its ability to perform probing. Touch trigger probing (TTP) is extremely versatile, but often there is a better tool for the job!
With the advent of quick-change adapters on robotic heads, it's now possible to utilize several sensor configurations on a single coordinate measuring machine. Furthermore, the changeovers between the different sensor systems are written into the software, so they can therefore run unattended.
Touch probing provides the coordinate measuring machine user with flexibility, but it doesn't do everything well. A scanning probe is a powerful addition to any CMM, mainly due to its ability to accurately measure form deviation and to quickly scan contours in a fraction of the time taken by touch trigger probes. Scanning probes also have dual capabilities, as they can measure discrete points like a touch probe or gather thousands of points per second in the machine's scan mode.
Most video probes feature ultra-high-accuracy CCD camera systems, and they occasionally use a laser locator. Upgrades also feature enhanced lighting packages, allowing the system to create contrast for better edge definition.
Applications for video probes include any part with densely populated features. They are ideal for electronic and medical devices; precision components with micro holes are also easily measured. Basically, anywhere the touch probe cannot go, the video system can and with extremely accurate results. Video probes may be mounted on the measuring machine’s change rack and swapped out for other probing when not required.
For soft-bodied parts that can be deformed by a touch probe, sheet metal parts, and other inspection applications where throughput and speed of measurement are important, laser technology is an excellent addition to your CMM and a sound investment. Laser scanners are best employed in situations where you need to repeatedly inspect similar parts, or where you need to combine free-form surface inspection with feature scanning.
Laser scanners can often be utilized in conjunction with touch probing, producing optimum results through the use of the right combination of sensors. Because of their high rate of data collection, laser scanners can create solid models from surface profiles, making the laser scanner ideal for reverse engineering, product development and rapid prototyping applications.
These sensors are also extremely valuable when comparing actual data to nominal data. A graphical analysis, illustrated in different colours, can be displayed on three-dimensional CAD models, showing the actual data overlaid on the nominal data. This visual representation allows quick decisions to be made on the shop floor, without the requirement of analyzing numerical data.
Many laser scanners gather 200,000 or more points per second, over a line width of 50 to 100 mm, with accuracies varying from 15 to 40 microns.
MAKING IT ALL WORK
Not only do you have the option of adding additional sensors to your coordinate measuring machine, multisensor machines are now available on the market. These systems come fully equipped with the three basic sensor technologies (tactile, laser and video).
Multisensor machines have some distinct advantages. For example, all the sensors are integrated so only one software package is required to drive the entire suite of probes. Generally, one fixture or setup covers the entire range of measurement requirements, saving time and additional expenditure for fixtures. The flexibility to measure all features with optimum probing technology provides better accuracy, increased repeatability and trustworthy measurements.
Multisensor technology can breathe new life into your existing coordinate measuring machine and greatly expand your measurement and inspection
This article was updated on April 19, 2018.