High-Speed Laser Shines at Shop-Air Cutting of Aluminum

Production Manufacturing Inc. processes 3/4-million lbs. of aluminum sheet a year at high-speed on linear-motor-drive CINCINNATI CL-707 laser cutting center.

Laser cutting of aluminum got a slow start, but it is catching up fast. Just ask Jim Napier, president of Production Manufacturing Inc., Hamilton, Ohio. PMI processes on average 3/4 million pounds of thin sheet aluminum a year at high speed on a linear-motor-drive CINCINNATI CL-707 laser cutting center. Moreover, speed is only part of the story - PMI also saves big time on assist gasses by using specially conditioned shop air.

"We started looking at laser cutting back in the early '90s," says Napier, "but the reflectivity of aluminum was a problem. We also wanted to avoid the costs of using nitrogen."

When Cincinnati Incorporated showed that it could solve both those needs, plus deliver state-of-the-art processing speeds, Napier was sold. "CINCINNATI was so far ahead of the curve, we knew it would give us a commercial advantage," he says.

Napier calls PMI a high-production sheet metal shop. "We run some steel, stainless and galvanized," he says, "but 90% of our production is aluminum, mostly in the .020" through the .125" range." Installed in 2002, the high-speed laser delivered faster throughput on volume jobs - as much as twice the processing speed of PMI's 1000 strokes/min turret presses, plus edge quality that requires no deburring or post-processing.

PMI typically cuts aluminum at 800 in/min on the CL-707. "We can run at 1100 and 1200," says Napier, "but then the machine may actually outrun the operator. We adjust the machine speed so it works comfortably for the operator and provides time for loading and part transfer."

Besides bringing high throughput to PMI's volume production, the CL-707 opened the door to new work and to part improvement opportunities. "Our customers want very tiny openings that our turret presses can't do," he says. "And, the laser makes it quicker and simpler to do prototyping and custom work. I don't have to blank everything and cut each part independently. Usually, we can cut everything from one sheet and have all the parts ready for fit-up and check-out."

PMI has worked with customers on redesigning parts to take advantage of the laser's capabilities. For example, notes Napier, one customer approved a change to a part made from rectangular tubing, requiring multiple cutouts and processing steps. Instead, PMI forms the 3D piece from a flat laser-cut blank, at considerable savings.

"We fight cost all the time - finding ways to produce parts for customers at lower costs by modifying the design and simplifying the processing," he says. "We're constantly looking for ways to do it better."

Thin parts are cut almost totally with shop air. "It has saved us a fortune," states Napier, co-owner of PMI along with Dale Henderson. In fact, that savings was key to PMI's cost justification for purchasing the machine. "If we couldn't have done it with air, we wouldn't have bought the machine," he says. He estimates that PMI realizes 65-70% cost savings by using shop air instead of bottled gas.

The laser is located in its own cell served by a dedicated, two-head reciprocal compressor. The heads typically alternate- one is running while the other rests. "We're not overworking the system," he notes. "Even if one head would quit or something go wrong, you know you've got air on line all the time." All the air lines are stainless steel and the system has its own filters and refrigerated dryer. "The cleaner your system is, the more precise your cutting will be," he says.

Air pressures and usage can vary with material - from 60 psi on 20-gage steel to anywhere from 115 psi to 165+ psi on aluminum, he notes.

The CL-707's diffusion-cooled resonator allows PMI to provide its customers with superior, consistent precision, particularly on edge quality and tiny, tight-tolerance part features. Diffusion-cooling delivers exceptional mode quality, allowing the beam to be focused into a smaller, hotter spot. The tight beam focus is especially effective on thinner materials, cutting faster and cleaner with narrower kerf, superior edge quality and small heat-affected zone (HAZ).

The combination of small HAZ and high speed processing minimizes heat input to the aluminum, avoiding thermal effects. "Flatness is a big issue with our customers," explains Napier. "Aluminum is difficult, because it holds the heat and is especially reactive."

The laser's precision and consistent quality are critical, he stresses. PMI can't afford mistakes. It cuts some specialty aluminum grades with polished, matte and pebbled finishes that can run as much as $4-$5 a pound, he notes, compared to 40 cents a pound lately for steel.

"We have a reputation for quality and are very proud of that," says Napier. "Quality, price and getting it there on time - that's what keeps our customers coming back. The CINCINNATI laser gives us a competitive edge on all three."