The production and manufacturing industries are becoming increasingly automated and complex. This has caused the development of complicated machinery to meet the demands of factories. As industrial components become more specialized, miniaturized and precise, there is an increasing requirement for 3D optical metrology, also known as 3D surface measurement.
Advantages of Accurate 3D Surface Measurement
Surface measurement is important. It is able to maintain machinery tools and detect inaccuracies and defects in the products produced. In some cases, minute differences in specification and manufacture can have a significant effect on the product’s application. Accurate 3D surface generation allows a company to be confident in all the products developed in their factories. It also has the added advantage of automating some of the processes.
Recently, there has been a surge of interest in the use of robots to perform high-resolution 3D surface measurement. Conventional surface measurement techniques use portable tactile profilers to measure a surface’s roughness. They also measure replicas. However, these can only be used on large parts and are unable to accurately determine surface defects or micro-geometries. This changed when companies started to use high-resolution 3D optical sensors mounted to automated robots.
One such system was discussed in “Robot solutions for automated 3D surface measurement in production” by Reinhard Danzl, Thomas Lankmair, Anne Calvez, and Franz Helmi. The system included the use of an optical sensor mounted to a collaborative six-axis robot.
According to their paper, the machine allowed for a fully automated measurement of the cutting edge geometry of large tools used in basic production. These tools included milling machine blades, which are used to make large aerospace turbine discs. They propose that the robot could be integrated into the cutting process by using a polishing cell. This cell could send measurement results to the machine, which corrects the part if it does not match with the correct specification.
ATOS 3D Digitizer
Another robot, the ATOS 3D Digitizer, uses fringe projection to accurately create 3D measurement data. Fringe projection is the method of projecting lines of light at varying intensities over an object, in order to triangulate the contours of an object. By using this technique, in just 1 to 2 seconds, the robot is able to capture approximately 16 million independent measuring points. Due to the number of data points, this automated robot is able to measure both large components and small, intricate machine parts.
Nanotechnology companies such as NanoFocus have developed intricate robotic systems which use optics, electronics, and CAD to create an industrially applicable surface measurement tool which analyses technical surfaces and custom products.
Applications of Automated 3D Surface Measurement
Automated 3D surface measurement can be used in a variety of industries. It can be used in fuel cell research, the manufacture of electronics and semiconductors, medical technology, material science research, art evaluation, solar technology, mechanical engineering, tool manufacture, and in the automotive and printing industries. Interestingly, automated 3D surface measurement can be applied to safety engineering, in which tools used by criminals can be analyzed and compared to fingerprints. With the use of accurate surface measurement tools, even nano-scale traces can be mapped.