Fraunhofer ILT: Laser deburring increases component quality

Burrs on cut and punched edges of sheet metal increase the risk of injury and often cause cable damage and scratched surfaces. For this reason alone, it makes sense to deburr edges. If this is done by laser, the fatigue strength of the components also increases, edges can be reinforced in a targeted manner and the tendency to crack is reduced. Laser deburring has become established in some large-scale production processes in the automotive industry over the last decade. "But the potential of this technology is far from exhausted," says Dr. Edgar Willenborg, expert for laser polishing and laser deburring at Fraunhofer ILT. Deburring sheet metal in particular is uncomplicated, improves component quality - and with processing speeds of up to twelve meters per minute, it is also fast and efficient. To get these messages across to experts, the Aachen-based institute's Polishing Group, headed by Willenborg, will be exhibiting at EuroBlech in Hanover for the first time in October 2024.

Laser deburring offers a long list of advantages

Up to now, mechanical processes have usually been used to remove burrs. However, research by Fraunhofer ILT shows that laser processes have clear advantages here. The process itself is uncomplicated. "The laser focus must hit the front of the sheet edge and cover it completely," explains Willenborg. There, the focused beam of light briefly melts the metal edge and burr. The surface tension then causes the liquid metal to smooth itself out. This creates a rounded edge. "Alternative process control makes it possible not only to round off the edge, but also to strengthen it in a targeted manner," says the expert. To do this, the power of the laser is increased. This additional energy input melts more material, which is placed around the edge like a reinforcing round seam. The smooth, round edges prevent cuts as well as damage to cables and surfaces. But the laser process can do more. It leaves defect-free edges. "This results in clear advantages in the fatigue strength and mechanical forming behavior of the sheet metal components," emphasizes Willenborg. Tests with high-strength steel show that its fatigue strength increases by 220 percent as a result of laser deburring. At the same time, the degree of forming up to the edge crack also increased by 240 percent. The expert explains the positive effects by the fact that laser melting eliminates any micro-defects from the mechanical processing of the edges. Such pre-damage, which is invisible to the naked eye, is often the starting point for crack formation.

Laser deburring is fast, clean and inexpensive

According to Willenborg, another major advantage of laser deburring over mechanical processes is that no grinding dust is produced. Instead of removing it, the excess material is only melted briefly. This also contributes to the fact that laser deburring is comparatively easy to integrate into existing process chains and production environments. Where integration is practicable, the benefits quickly become apparent. "Laser deburring is particularly advisable for highly stressed components," he emphasizes. He cites chassis parts as an example: The increased fatigue strength in the edge area allows their manufacturers to design them to be thinner and therefore lighter and ultimately more fuel-efficient. When it comes to formed 3D sheet metal components, the laser can be mounted on robots. One advantage here is that fiber-coupled diode lasers are used for deburring anyway. According to Willenborg, the standard lasers in the near-infrared wavelength range are also inexpensive and readily available. The Fraunhofer expert invites interested parties to find out more about the possibilities of laser deburring and the latest processes for laser polishing sheet metal at EuroBlech 2024 in Hall 27, Stand D142.