The fact that cars in factories get painted by robots is not a surprise to anyone. The car production process is highly automated and automation is only progressing. In fact, it is the car industry that is leading the industrial robot revolution, encouraging human-robot cooperation in the workplace. But some parts still require human attention.
The terahertz-based measurement system is way more automated and cost-effective. Image credit: BMW
Having in mind that car producers are among the biggest employers in Europe, it seems obvious that people are involved in car manufacturing, even though robots do a lot of the hard work. Quality assurance is one of the steps that require human eyes and hands. After the car is painted, how can you tell that the robot did a good job and achieved a thick uniform layer of paint? Well, if the part is metal, paint‑thickness gauges can be used – these are able to estimate the thickness of the paint layer by measuring magnetic induction. The process is very different when the part is made from plastic.
Up until recently, in BMW’s Plant Leipzig paint layer thickness inspections on plastic exterior components involved scalpels and microscopy. Inspectors literally cut through the paint to measure its thickness. Obviously, this was not done to each part, only a few from each batch, to make sure that robots are working as intended. This cutting and measuring process using scalpels is destructive and causes waste. There are better ways.
The Plant Leipzig is now introducing a terahertz-based measurement system for this purpose. This method is non-destructive and is completely automated and integrated into the production process, which means that deviations from the standard can be identified very early.
How does terahertz-based measurement system for plastic parts work? Naturally, robots are involved. Instead of measuring magnetic induction, which obviously wouldn’t work with plastic, sensors analyze the time‑of‑flight of reflected terahertz waves. Terahertz waves are electromagnetic waves with frequencies between 0.1 and 10 THz (and one THz is 10¹² Hz).
Terahertz-based measurement saves time, refuses waste (since it’s non-destructive) and produces quick accurate results. It might actually help ensure a higher standard of quality too, although people were never complaining about BMW’s paintjobs.
“The combination of higher measurement accuracy, direct process integration and full digitalisation delivers tangible benefits across the entire production chain, strengthening quality, economic efficiency and resource conservation in equal measure,” Christoph Theiselmann, Head of Exterior Plastics, Production at Plant Leipzig, said.
Written by Povilas M.
Source: BMW
