Advances in laser power for tube processing haven't been as monumental as those seen for flat-sheet metal. But that's for a good reason. PHOTO courtesy TRUMPF.
We live in a world of tubes. From our homes and furniture to our cars and exercise equipment, there is such a variety of components requiring metal tubing they make for a wide range of opportunities for job shops looking to serve new markets. What’s more all these components can be produced using fibre laser systems, doing away with many of the traditional work steps—sawing, drilling, milling, deburring—in the process.
If you’re looking to get into tube processing using fibre laser, here are five considerations to keep in mind when selecting which laser tube cutting system to go with.
1.DON’T BE POWER HUNGRY
The rapid advances in fibre laser power for flat-sheet metal processing are downright impressive but don’t expect to see such increases on the tube side, and for good reason, as Adi Buerkler, TruLaser Tube product manager for TRUMPF, explains. The most obvious difference between sheet and tube is that tubes have a closed shape with an opposite wall that can be affected by what happens during the initial wall cut by the laser. Buerkler points out that TRUMPF has increased power with tube over the past five years, starting at 2 kW and now offering 6 kW, and that’s plenty.
“The reason you don’t need the same kind of power in tube that you have in flat sheet is that the wall thickness of the tubes you’re working with is typically a half inch or less. Cutting half inch tubes with 6 kW is more than sufficient,” Buerkler says, emphasizing that with more power “you would blow a hole on the other side.”
2. FAST BUT STEADY
Another important consideration when selecting a laser tube cutting system is that the material moves throughout the process. After being loaded into the cutting area, the tube continues to be moved during the job back and forth. The rotations are at high speed and at times high acceleration. That places a lot of stress on both the material and the machinery. If you’re processing thin, flexible tubes they can bend and jam if not properly guided. Heavy tubes apply stress to the machine from shocks and vibrations, so the machinery has to be built in a way that makes it capable of withstanding all the pressure placed upon it long term.
“That’s why our machines are dynamically controlled. So if you load a six-inch tube that is mild steel and quarter-inch thick, it will act and move differently than if you were to load a two-inch tube that is quarter-inch thick. Same material, same thickness, same cutting gas, but different weight per foot, therefore the machine is going to manipulate the material in a different way,” says Robert Adelman, North America laser product manager, BLM Group.
3. SUPPORT ACCURACY
How longer tube lengths are supported also needs consideration. Does the system have enough chucks to ensure positioning accuracy when the tube is rotating? Support for the tubing on both sides of the cut area prevents the inaccuracies that can occur if the tube is unsupported on one side. Buerkler says TRUMPF chucks are pneumatic chucks rather than hydraulic for greater accuracy.
“We have four rollers to support the material, feed it through, and turn the tube or profile. On our TruLaser Tube 3000 and 5000 fibre laser the chuck can open up fully. It can go from 0 up to 6 inch and bring in the tube without collision problems,” Buerkler says. “We can control the pressure, adjusting to a lower pressure for lighter, thinner tubes or higher pressure for thicker, heavier tubes, which allows us to control the bow and always get perfect accuracy. Also, the cutting head is an inch away from the rollers to maintain accuracy.”
4. KEEP IT CLEAN
With laser cutting there are sparks and debris and slugs that fall inside the tubing. This must be dealt with, or you risk damage to the tube. Look for fibre laser machinery that provides “clean tube” technology or what is commonly referred to as a “spoon”.
“It’s an option we offer on all our fibre lasers,” says Adelman. “It is a device that is installed in the machine, located on the unloader, and it is equipped with a suction device as well as anti-splatter protection so that the splatter doesn’t make it to the other side of the tube. It’s captured, sucked up, and evacuated. Our smaller machines are used to process tubes with smaller thicknesses so there are differences in the spoon device used but they all work based on the same concept.”
5.SECURE STORAGE
From the time the tube material is received to when it’s processed, proper storage keeps it from being deformed. Look for systems which can be paired with the laser tube machine for greatest ease of use and efficiency. That’s something BLM Group offers with its larger machines and absolutely recommends it, says Adelman.
“The higher the power the faster the machine, so now what you’re waiting on, if you don’t have a tube storage system, is loading and reloading. Most of our tube lasers come with a bundle loader so you can load a bundle and work four to six hours off that bundle. But when that bundle is done, if the operator is on a break or the person picking the new material didn’t do it, you have the machine on standby waiting on material. A better way of doing this is connecting your storage system directly to the machine so that the correct material is picked, arrives at the machine in time and you’re not having material stored that is getting bowed, twisted, or damaged in any way,” Adelman explains. The system can also be integrated with the ERP for better inventory management. SMT
