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Capture 20000 points per second by upgrading your CMM with a laser probe
Laser scanners capture thousands of points every second, drastically improving reverse engineering and inspection processes. A laser probe can reduce the time needed to measure complex parts from hours or even days to just minutes. The resulting data from a laser scanner is a 3D pointcloud that can be further processed for reverse engineering purposes or even more applicable for inspection purposes where the 3D pointcloud is compared to the original CAD model.
Limitations of tactile probing
The key advantage of a touch probe is definitely the ability to measure individual points with a high level of accuracy. Recent trends are however highlighting several limitations of a touch probe.
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The part geometry has grown increasingly complicated often with complex 3D contours. As a result, thousands or even millions of points are required to accurately model geometrically complicated parts. The time needed to capture single points can grow to days or sometimes weeks for complicated parts.
New materials are constantly introduced in today’s products. Measuring the surface of flexible or fragile parts with a touch probe, will create an indentation reducing the overall accuracy or damaging the part.
Principle of laser scanning
Laser scanning is a new technology that easily overcomes these problems, making it ideally suited for today’s quality control and reverse engineering challenges. Laser scanning systems work by projecting a line of laser light onto the part surfaces while cameras continuously triangulate the changing distance and profile of the laser line. The image of the line is then translated into 3D coordinates.
Benefits of laser scanning
Laser scanners are able to quickly measure large parts while generating far greater numbers of data points than probes without the need for templates or fixtures. Since there is no contact tip, the problems of depressing soft objects, measuring small details, capturing complex free form surfaces are eliminated. The laser scanner can also be programmed for automated inspection of volume parts. The operator can switch from laser probe to conventional touch probe in minutes, so no functionality of the original CMM is lost.
Different scanners serve different purposes. The all-purpose LC50 laser stripe scanner is typically used for scanning larger parts at high speeds. The laser width of 50mm enables to digitise a part in very fast way.
The smaller LC15 has a 15mm by 15mm field of view making it ideally suited for capturing the smallest details at the highest accuracy. This laser sensor is often used in applications where small objects such as electronic parts, mobile phones, small turbine blades need to be inspected.
Finally the XC cross scanner is a patented high-speed, multi-stripe laser sensor that enables more efficient scanning of features such as holes, slots and gap & step that are typically inspected in automotive applications. A higher speed and increased flexibility is obtained for real 3D measurement by avoiding the use of a motorized sixth axis.
Typical applications where laser scanning is particularly suited are e.g. sheet metal, engine parts, windows, turbine blades, mobile phones, electronic components and many more. Today even complete cars are scanned for inspection.
Applications for laser scanning
The laser scanning is particularly suited for two applications, namely reverse engineering and full part inspection. These applications are found as well in automotive, aerospace, energy as in medical or consumer goods industry.
Due to the completeness of the measured data, the reverse engineering of the most complicated parts can often be accomplished in a couple of hours. Paraform, Metris’ solution for reverse engineering, turns the measured pointcloud into curves, NURBS surfaces or solids, which can be further used in downstream CAD/CAM applications such as design or manufacturing.
An even more significant application is the inspection of first articles or production series. CADcompare, Metris’ solution for 3D inspection, aligns and compares the actual measured part to the original CAD file in no time. The result is a color deviation plot that shows in a glance how much the part deviates from the original design. This goes far beyond the dimensional checks that can be performed with touch probes. Therefore laser scanning opens a new world for the manufacturers since important time is saved during the design, prototyping, pre-production and production cycles. Also the design engineers have better information about the quality of the parts, which ultimately saves the company money and produces a better end product for the consumers.
Conclusions
Upgrading a CMM with a laser probe can significantly improve productivity and reduce reverse engineering and inspection time. Also the ability to capture complete geometries rather than a limited number of points improves overall part analysis and thus quality.
Download: 3D Laser Scanning (ENG) (PDF file)
Download: 3D Laser Scanning (FR) (PDF file)
Download: 3D Laser Scanning (DE) (PDF file)
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