|Fringe Projection for Fast Scans
New ZEISS 3D sensor speeds up digitalization of parts
|Optical metrology is not new to the world, but it is a cutting-edge technology
topic for most industries. The fringe projection technology, in particular,
opens up various application possibilities. Carl Zeiss Optotechnik GmbH has
now launched a successor model of this sensor in the market, ZEISS
"Even if not all measurement tasks can be solved optically, they are suitable for an increasing number of industrial applications," says Dr. Marcus Steinbichler, Managing Director of ZEISS Optotechnik. The great advantage of all optical 3D measuring methods is their speed with which they capture many measuring points at a time – and is on a continuous technological evolution path. With the new 3D sensor ZEISS COMET LƎD 2, ZEISS has now reduced the measuring time by 50 percent per sequence compared to the predecessor model. So, as much as 5 million measuring points can now be captured in one second. "With our new system, fringe projection has become even more interesting for companies", Dr. Steinbichler claims. The CEO's expectations do not seem to be over the top, as the forerunner model, ZEISS COMET LƎD, has already been an industry favorite for several years.
|Blue light visualizes geometries
The new generation of the ZEISS COMET LƎD 2 fringe projection sensor uses advanced optical technology. It has a projector module which projects blue LED light as a striped pattern onto the measurement object. This pattern is specifically distorted by the geometry of the respective component and captured by a camera. A software links the individual camera pixel to a point on the part via triangulation calculations. The point cloud generated in this way is then converted to a triangle mesh in STL format, with which a 3D model can be generated. This model can then be used for target / actual comparisons to the 3D CAD model. Compared to laser scanners, fringe projection provides more precise results. For this reason, this method is particularly suitable for quality assurance, as the following applications prove.
|Focus on quality – Total Quality Improvement.
"Good quality is of crucial importance. There is always room for improvement!” Ernst Mahle, the company founder of MAHLE Group, made this statement more than 100 years ago, but it is still one of the company's most important business maxims. For this reason, MAHLE Behr GmbH & Co. KG, headquartered in Stuttgart, continually defines more effective standards for quality planning during product development and production start-up, and systematically monitors internal production processes.
When MAHLE took over Behr company in 2013 - a German family-owned company that e.g. manufactures air-conditioning for cars – a decision was made: the stainless-steel rectangular tubes used for producing EGR coolers for cars and trucks
should no longer be purchased from external suppliers, but produced in-house on a production line planned specifically for this purpose. This required random dimensional inspections to be carried out in series testing, combined with a new measuring system.
|Focus on total surface
MAHLE Behr defined several requirements for a new measuring system. For instance, it should be able to do even two-dimensional (2D) evaluation of the wall thickness across the stamped area of the tube as well as of the pipe ends. In addition, an automated measuring process and a compact measuring system were required since the plant operators should carry out the measurements in a small measuring room directly on the production line. The measurement system should also be easy to duplicate so that it could be used for future production lines worldwide. The fringe projection sensor ZEISS COMET LƎD met all these requirements. As the entire surface can be analyzed and evaluated using false-color representation, the machine operator is able to make any necessary fine adjustments of the slider on the stamping press while still maintaining the required minimum wall thickness. Moreover, geometric dimensions can now be tested to enable error-free automated assembly.
|Reduction in measurement time
Not just MAHLE Behr, but also HERU Werkzeugbau GmbH & Co. KG uses the fringe projection sensor for demanding applications in quality control. Founded in 1987, the company develops and manufactures complex sheet metal parts as well as numerous tools. Tactile measuring machines are used to measure the components in order to ensure high product quality, however, these machines were reaching their utilization limits. The requirement for fast, complex measurements in series production was gradually becoming the primary focus of quality assurance. "We have now become so accustomed to this convenient measuring system that we can no longer imagine quality assurance without it," emphasizes Markus Hesse, Managing Director of HERU Werkzeugbau GmbH & Co. KG, Lennestadt-Grevenbrück, "We should have taken this step much earlier." Due to the possibility to do target / actual comparisons quickly and with minimal effort as well as the easy handling and the fast analysis of new parts, the company decided to opt for a ZEISS COMET LƎD. It fulfills the desire to perform fast measurements – in less than two seconds per sequence, even complex parts are scanned.
|Faster product development
The ZEISS COMET LƎD sensor not only proves its advantages in quality assurance, many companies also use the system for product development, such as the shoe manufacturer Lorenz Shoe Group AG from Austria. The development of a new shoe model starts with the creation of a master model that is used as the basis for the subsequent series production. In order to create new models more quickly, the company employing more than 1,000 employees was looking for a measurement system to digitize the shoe lasts and then develop the soles in 3D. With the COMET LƎD and the automated COMETrotary turn-table for positioning of components, the master model is now fast and easy to measure, and the master data can be created and saved in just a few steps. "By introducing the COMET LƎD sensor we have been able to reduce development lead times to a fraction of what they used to be" says Florian Kaidlsdorfer, developer at the Lorenz Shoe Group, "We can respond much faster to fashion trends and develop intermediate collections for our own international retail business."
|3D data for unique glass objects
Cristalica GmbH, a glass factory in Döbern, Germany, is even one step further in product development than the Lorenz Shoe Group. It allows the end user to modify existing 3D models of their products and thus create unique designs. Before the introduction of the ZEISS COMET LƎD sensor, samples had to be manually measured and recorded in order to display them digitally. The portable ZEISS sensor makes 3D data acquisition much easier, faster and more accurate. In addition, the handling is very convenient for its users. The glass factory also uses the 3D data obtained by the ZEISS system for quality assurance and for preparation of series production.
|Wide range of applications
Bernstein Innovation GmbH also appreciates the range of applications of the system. "The ZEISS COMET LƎD has paid off from the very first day," says Stefan Niedermair, CTIO of Bernstein Innovation GmbH. The Austrian company develops and produces consumer goods by means of 3D printing and was initially looking for a measuring system that precisely captures complex geometries and can measure a wide range of component sizes ranging from a few millimeters up to 55 cm edge length. With the acquisition of the ZEISS COMET LƎD, another field of application soon opened up: digitalization of components. Thus, the company can easily create 3D components which have not been digitized. This provides enormous potential for the 3D printing.
Although ZEISS COMET LƎD can already be used for a wide range of applications, because of its performance parameters and its compactness, the new ZEISS COMET LƎD 2 which has been available since February 2016, will "continue to drive this development," claims Herbert Daxauer, Product Manager 3D Digitizing. A significant advantage for companies looking to scan complex and or large components is a short measurement time of only about one second. They can save up to one hour of measurement time during each project. As the sensor is even more compact than its predecessor, it is even more handy. This is an advantage when, for instance, interior or compact spaces are to be digitized, or when the sensor has to be transported to different sites. As with the predecessor, the modular design allows changing the measurement field easily and quickly. For this reason, companies can solve different measurement tasks with just one sensor. According to Mr. Daxauer, the developers of the ZEISS COMET LƎD 2 have not only limited themselves to improving the existing functions, but have also created new features. The new sensor detects changes in exposure and vibration. An innovation that, according to Mr. Daxauer, "reduces the uncertainty of measurement and thus inspires product developers and quality managers".
for Inspection Engineering® .
Last updated July 24, 2017