What Do You Do With All Those Parts?

The PartMaster® from TRUMPF reduces offloading time by bringing the parts to the operator stationed at the end of the conveyor. Photos courtesy of TRUMPF.

Faster than the speed of … well … a solid-state laser. Not to knock CO₂ equipment—it’s holding its own on the manufacturing floor—but solid-state technologies can produce parts from thin sheet four or five times faster than their CO₂ counterparts using the same power. That kind of speed can be a game-changer, a competitive advantage, a challenge.

Does it really translate to shorter overall production time when a solid-state laser spews out parts at a lightning-fast speed? It can with help of advanced planning and automation. But without help, those rapidly produced parts could stack up, cause grief for the operator, waste cutting time, or simply push a bottleneck downstream.

“No matter what kind of laser you have, you want to maintain the uptime of the machine; keep it going as fast and as frequently as possible. You don’t want it sitting idle because a person or component can’t keep up,” said Stefan Fickenscher, product manager for TRUMPF’s TruLaser product group for North America, Farmington, Conn. “As a result of increased cutting speeds from the solid-state lasers, the operator or the person unloading the finished material and loading the next sheet has to be faster.”

Keep the Optics Flying

Fortunately, increased speeds haven’t been limited to the cutting process. The speeds of automatic loading and unloading equipment have been ramped up so operators don’t have to maintain an aerobic pace to keep up. Automation has also become more creative, giving manufacturers a choice between compact systems that take little more floor space than the laser itself or modular systems that can grow along with production demands.

Regardless of the type chosen, the need to couple automation with the purchase of solid-state lasers has not gone unnoticed. “About 93 percent of our fiber lasers have been sold with some sort of automation,” said Jason Hillenbrand, laser product manager at Amada America, Buena Park, Calif. “As a comparison, CO₂ lasers have a share of around 30 to 40 percent of the purchases that include automation.”

Aside from upping the cycle speed, solid-state technologies haven’t prompted a rush of substantial design changes in laser automation. Modular systems designed to tend multiple machines will service a mix of solid-state and CO₂ cutting tables.

Mike Monaghan, service department manager for MC Machinery Systems, Wood Dale, Ill., said, “We can add up to four of any type of laser tables to our modular system. It’s just a matter of extensions, possibly a set of carts. One company with our largest system ended up with 1,100 shelves and load/unload systems running 18 machines.

“The modular automation is quick, so it keeps up with the fiber lasers, but you need to schedule your production to take advantage of the efficiency,” Monaghan continued. “As more lasers are added, the time to load and unload takes longer because the automation is traveling farther. So you put the longer sheet cutting times on the laser that is farthest down the line. With our system, the load/unload automation averages 1 minute for laser one, 21⁄2 minutes for laser two, 4 minutes for laser three, and around 6 minutes for laser four.”

Creative expansion of existing automation systems can also alleviate problems caused by faster parts flow. “In one case, a manufacturer had an automation system working with their CO₂ machine and they added a fiber laser. Supplying the two machines, especially with the fiber’s speed, became a problem,” Hillenbrand said. “So we retrofitted the original system with an additional loader. One loader was dedicated to loading and the other was dedicated to offloading.”

Get a Grip on Offloading

Offloading is an area that still presents challenges. Many offloading systems use a rake system to push the completed skeleton and parts off the table onto a pallet or cart. Part separation is a separate process.

Automation options are sold with most solid-state lasers to avoid wasting cutting time while material is loaded and parts are unloaded. Photo courtesy of MC Machinery Systems.

“Part removal is still not a perfect science for any of the lasers,” Hillenbrand said. “The problem is that as you cut parts and leave them in the skeleton for offloading, there will be some twisting or turning, especially with the thin materials. And smaller parts tend to tip up so they may need to be cut with a tab to keep them in place when the skeleton is unloaded. That can keep the parts flat, but the negative side is that the operator has to pop the part off of the tab as well as separate it from the skeleton.”

A different take on parts removal is a conveyor system that brings the completed sheet to the operator. Fickenscher explained, “The conveyor system lets the operator stand in one place and the parts and skeleton move towards him for sorting. It saves about 30 percent of part removal time so the laser can keep cutting. The height of the system is adjustable to save back strain, and the good ergonomics keep the operator from becoming fatigued.” In a lights-out situation, the conveyor can be replaced with a pallet.

Vacuum sorters are a possibility, but they need to be carefully evaluated to ensure that they can keep up with the cutting speeds and work with the usual part configurations. According to Monaghan, they are most effective when paired with generic types of nests.

“Automatic vacuum part removal and stacking can be a difficult process as far as consistency goes, especially with consumable tables, but it is something customers are pushing for,” said Hillenbrand. “If you have any deviation in table flatness, the part will drop down and be difficult for the vacuum cups to grab. And if you swap tables before picking the part, there is potential for the part to shift or slide under the skeleton.

“No matter how you offload parts, the process needs to be evaluated. We look at the parts mix and help determine which process to use. It might be that automatic offloading will work for 50 or 80 percent of the parts, and the rest will require a different process.”

Avoid Downstream Pileup

As with any cutting process, material thickness and part complexity determine the processing time, but with the solid-state lasers it is not unusual to see large parts or a nest of simple parts completed in two minutes or less. Downstream processes need to be evaluated to avoid piling up WIP. That management might involve the purchase of new equipment along with the solid-state laser and its automation.

“Most people have an idea of what they will need to get the parts through production,” said Monaghan. “So, for example, they will include an additional press brake or a press brake with automation to speed up that process. If the parts do start to stack up, they can be stored in a tower system and retrieved as the downstream process catches up.”

Fickenscher said, “It is important to set up the production cells in the best way, and that means taking material flow into account. Automation teams from the equipment manufacturers can support and consult as automation is added to keep parts moving and allow for production flexibility. Knowing that the solid-state lasers are really fast, our task was to come up with automation solutions that help our customers so they are not waiting for a person or device.”