Automatic focus control gives manufacturers the tool they need to laser cut parts with varying thicknesses
Above: Laser Mechanisms’ FiberCUT STa gives manufacturers the ability to cut material of varying thicknesses with its programmable focus position adjustment feature.
December, 2023- Mixed materials have become the hallmark of carmakers seeking to develop lightweight, sustainable, fuel-efficient vehicles. The movement has grown exponentially since Ford switched the body and bed of its F-150 truck to aluminum in 2015. For manufacturers, the trend can translate to laser cutting parts with varying thicknesses. Automotive body components, for example, have transitioned from traditional steel unibody assemblies to aluminum castings. Tailored blanks have moved to lap-welded hot-stamped parts. Gauges can more than double when cutting these components.
The need to adapt cutting and trimming processes to changing material thicknesses prompted Laser Mechanisms Inc. to develop a laser processing head with the capability for automatic focus control. The company specializes in the design and production of laser beam delivery components and articulated arm systems and introduced FiberCUT STa at Fabtech 2023. The processing head collimates and focuses a fiber-delivered laser beam and directs it through the nozzle for optimal metal cutting. Its programmable focus position adjustment improves manufacturers’ ability to cut material of varying thickness. Operators can also pierce metal very quickly. Paired with a 16 kg robot, FiberCUT STa can perform 3-D cutting with up to 30 mm of programmable focus-to-tip adjustment.
LIGHT YET STIFF
“Castings are designed to be a structural support for other components in a vehicle,” says Tom Kugler, fiber systems manager for Laser Mechanisms. “Strength requirements dictate changes in material thickness, especially in areas where other components need to be mounted. New casting technology means a carmaker can replace a dozen or more components with one large, intricate casting. It’s critical for a supplier to get good quality cuts on parts that may be 1 mm thick in one area and 5 mm or more thick in another section.”
When focus position is optimized for only one thickness, it produces poorer cut quality, higher dross and slower cutting speeds, as seen in the thicker areas of this aluminum casting.
FiberCUT STa’s programmable focus position adjustment delivers excellent cut quality and faster cutting speeds in material with varying thicknesses
Hot stamping allows automotive manufacturers to make stronger, lightweight equipment for improved fuel efficiency. Suppliers can also use it to produce complex items in a single process. The technique yields a high-strength multi-component that is lighter yet stiffer.
“Hot stamped parts harden once they are quenched in the die,” says Kugler. “You cannot cut the material with anything but a laser. New hot-stamped parts involve lap-welded assemblies for stiffer, stronger zones. Cutting these parts with step changes in thickness requires a different laser focus position for optimum piercing, and cutting speed and quality. By providing an automated focus control system, we can program thicknesses into the robot for high-volume jobs.”
A complete FiberCUT STa system consists of a cutting head, motorized fiber collimator and linear drive with position monitoring. Internally plumbed wiring and assist gas lines avoid costly snags and breaks. The FiberCUT STa works with all fiber laser systems up to 6 kW with wavelengths of 1030- 1080 nm. Laser Mechanisms works with an integrator for robotic solutions, which can run in line with auto load and unload.
The focus position of the laser in relation to the surface of the material is critical for cut quality and speed when piercing. The operation involves drilling a hole in the material to be cut, which allows the laser beam to enter at the top of the cut zone and molten metal to fl ow from the bottom. “If piercing isn’t clean, it can slow the process and create defects,” says Kugler.
“A bad pierce can create a volcano of material in aluminum around the pierced hole. A clean hole means the fiber laser can cut at maximum speed with no defects. The ability to adjust the focus for different thicknesses results in minimal dross. Metal left hanging beneath the cut can be unsightly or require a secondary process to remove it. Consistency of piercing means consistent part quality.”
Piercing with focus near the tip exit creates a buildup of material resulting in poor cut quality for the lead-in and first part of the hole cutting path.
Laser Mechanisms introduced its FiberCUT Straight laser processing technology in 2009. The original model allowed an operator to set the focus of the laser cutting head in the optimal position. “That worked well for single thickness sheet or material that varied by just a couple of millimeters,” says Kugler. “Today we are seeing variations close to 10 times that [range].” FiberCUT STa’s nozzle senses the required tip standoff from the workpiece and automatically maintains that standoff through its internal drive system. The latest model was engineered specifically to withstand the harsh environment of a job shop or factory production floor. “We’re always looking at the market and working to anticipate what we need to do to make improvements to our products,” Kugler says. “At the end of the day, it still comes down to cut quality, speed and piercing.”
Laser Mechanisms Inc., 248/474-9480, http://lasermech.com/