Combo Machines: It's All About Throughput

By: Lou Kren

Thursday, June 1, 2017

After World War II, Japan sought to regenerate its auto-manufacturing industry. During the war, needing to produce trucks, buses and military equipment in large quantities with little specialization, Japanese plants could, and did, mimic the production strategies and large lot sizes of American automakers. But after the war, Japanese manufacturers shifted to satisfy domestic demand. Here, vehicle and part lot sizes frequently numbered only in the hundreds or, at most, a few tens of thousands.

Whereas in the industrial age the goal always had been higher and higher production volumes with as little variety as possible to achieve economy of scale, the end of World War II signaled a manufacturing sea change. Led by Japan, which had to find ways to produce products economically in lower volumes, the quest to profitably manufacture smaller and smaller part lots of greater variety began. And it continues to this day.

Goal: Maximize Throughput

As job-shop fabricators know, today’s work schedule can see hundreds of part jobs with part lot sizes topping out in the hundreds—or less. Given this fact, throughput must be optimized.

That is the whole idea behind the development of combination laser-punching machines. These machines, in operation since the 1970s, can deliver benefits above and beyond those of separate machines, if fabricators focus on throughput as opposed to singular process time.

“The key to job-shop sheetmetal fabricators meeting low-volume, high-variety challenges is having a piece of equipment that can deliver a number of processes in one platform,” says Brian Welz, product group manager at TRUMPF Inc., Farmington, CT, speaking of the efficiencies of combination machines.

Advances in punching and laser technology have made combination punching and laser-cutting machines potent allies in helping fabricators navigate a changing manufacturing world where part mix increases while job volumes drop. The flexibility of two systems in one enable multiple processes to take place at a single station, cutting time and costs associated with secondary processes performed on other machinery.
“At your production facility, every day is like race day,” he offers. “How many laps do I need to win the race? Today, I need to go 500 laps. Some days, with breakdowns and other problems, I may only go 480 laps. Other days I may go 520. To succeed, I need to keep my car racing on the track. Success means being able to change over and move from job to job to job and progress, turning those laps and producing those parts to satisfy production requirements.

“Secondly, we race against the competition,” Welz adds. “How do we as a company separate from the competitors in order to provide product faster and more effectively, and at the lowest cost?”

Multiple Process in One Location

Successful job shops gain efficiencies by performing as many actions as possible at a single location.

“I’ve seen fabricators embrace the ability to conduct multiple operations at one machine stop,” says Welz. “At one machine a user may countersink, place holes, tap certain holes, etc. In contrast, transporting a part from one location to another to perform these functions, and then tracking that part throughout the process, is extremely costly.”

In assessing the value of a combination punching machine and laser cutter, Welz explains, fabricators should consider the entire throughput time, and not be hung up on processing time for a single operation. Focusing on single-operation time may lead fabricators to send parts from location to location, where advantages of a quick operation are more than negated by the aforementioned travel inefficiencies. While a laser-cutting machine can take 1 to 2 sec. to create a hole, a punch machine may take a quarter of a second, if that. Welz cautions not to try switching from machine to machine to capture those speed differences.

“For example,” he says, “a job shop may need to make a 12 by 16-in. part from 1⁄8-in.-thick material, and this part requires a series of holes and a countersink as well as some tapping. The job shop first takes that job to a laser-cutting machine, which rips through its tasks in 8 sec. Now this unfinished part is removed from that machine and placed in a bin for travel to another machine for another task. In this process, the quick laser-cutting speed is negated and then some.”

Multiply that by the number of processes and station changes, and the efficiencies of a laser or punching machine are removed.

“A combination laser-cutting and punching machine, on the other hand, performs all of the required processes in one station, with the same edge and hole quality gained by using those machines separately,” says Welz. “From a throughput standpoint, when looking at the time allotted for creation of a complete, finished part, a fabricator often will see that the combination machine is much faster because the entire process has been enveloped in a single station. This is a very diverse piece of equipment that can adapt to incoming projects, and do so economically.”

Offering the Latest Technology

Combination laser and punching machines certainly have shown their worth, bringing the best of both processes in a single platform, and incorporating advances in each of the technologies. An example, explains Welz, is Trumpf’s 2016 introduction of a new combination punching and fiber-laser machine.

“Fiber lasers have become the accepted laser performers in the fabrication market, due to rapid cutting speed, reduced maintenance requirements and process stability,” he says. “The ability to marry the fiber laser and punching machine on an economical platform has been well-accepted in the market.”

With JIT and lean manufacturing, running thousands upon thousands of the same part no longer is common for job-shop fabricators. As punching machines offering increased speeds and process capabilities combine with improved laser technology, thriving in a low-volume, high-mix environment is well within reach. MF


See also: TRUMPF Inc.

Related Enterprise Zones: Fabrication

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