FFJ 0317 face squareFace Time - Processing heads with integrated beam shaping and beam steering options give rise to new applications, says Hans Herfurth, director, global business, at Laser Mechanisms.

September 2019 - Processing heads with integrated beam shaping and beam steering options give rise to new applications, says Hans Herfurth, director, global business, at Laser Mechanisms.

Q: What process scenarios can laser beam shaping and steering accomplish that traditional laser processing heads cannot?MM 0819 face lead

A: Special processing heads that form rectangular spots with homogenized intensity distribution are often preferred in surface hardening and cladding applications to create wear-resistant surfaces on larger parts and tooling. Using the rectangular spot, larger areas can be treated in less time with fewer overlapping tracks, something not achievable with the traditional round spot. Combining the rectangular beam shape with a zoom module allows on-the-fly adjustment of the beam width to match the width of the wear zone being treated. Integrated process monitoring and control measures can adjust the laser power automatically with changing spot dimensions to maintain constant intensity in the spot and achieve consistent quality.

Scanning heads that steer the laser beam in two or three axes at high speeds within a limited processing space are in wide use. Examples include marking materials, high speed drilling of solar cell wafers, welding battery cells and automotive seat frames.

More recently, processing heads that provide fast beam oscillation with small amplitudes (stir welding) superposed to the regular beam path have opened further applications. Freely programmable oscillation patterns enable better control of the heat input and melt pool shape during welding. This has led to significant improvement in quality for laser welding of dissimilar materials and materials that are otherwise difficult to join with lasers, such as copper. Laser beam oscillation is also successfully being used in additive manufacturing to optimize the heat input for powder and wire-based direct metal deposition processes.

Q: Beyond welding, how can an oscillating laser beam work to improve cutting accuracy?

A: Beam oscillation mainly improves process capability, performance and quality. Recently, the first industrial laser cutting system using beam oscillation was introduced to the market. The oscillating beam widens the cut kerf, which makes it easier to eject the melt out of the kerf and therefore enables higher cutting speeds.

Q: What is twin-spot laser welding?

A: For twin-spot welding, the processing head includes a beam splitter module that separates the incoming beam into two. Each creates a focus on the workpiece surface. The two foci can be oriented perpendicular in the weld direction to widen the melt pool and bridge gaps between sheets or in-line with the weld seam to elongate the melt pool and help with degassing to reduce porosity and weld spatter. Twin-spot welding is used to make tailor-welded blanks, joining sheets of steel or aluminum with different thicknesses, material properties and surface conditions.

Q: Has improved beam manipulation contributed to a growth in applications for stir welding?

A: Definitively, yes. Many sectors that produce sheet metal components, structures and parts made of high-strength steels, aluminum alloys and nonferrous alloys use this welding technique to achieve high weld quality. A growing field of application is in making electric vehicle batteries. Here, welding of copper and other dissimilar material joining is required in the battery assembly process, and laser beam oscillation is an enabling technology.

Q: Can these heads be retrofit onto existing equipment?

A: Yes. In most cases, processing heads with unique capabilities can be retrofitted to existing machines and custom solutions can be provided.

Q: What steps should companies take when implementing this technology to achieve the best results?

A: Best results begin with a thorough evaluation of the application and a clear definition of the expected quality and production requirements. At Laser Mechanisms, we have a multidisciplinary engineering team that includes laser, design and application engineers that specify the entire beam delivery system, including the processing head. In some situations, feasibility- and product-related studies are needed to customize the design for optimum performance. n

Hans Herfurth is director, global business, and part of the industrial sales team at Laser Mechanisms, Novi, Michigan. He has more than 30 years of experience in laser technologies, from applied research and development for government and industry to the design of industrial laser applications and systems.