Continuous Production Doubles Shop's Output

When considering continuous production versus batch production, a shop has to weigh the pros and cons. If a batch of a product is not selling, then the manufacturer can cease production without sustaining huge losses. Batch production is useful for companies that make products for which demand is difficult to forecast. Also, some smaller businesses can’t afford continuous production. For shops with high-volume orders, however, the production-cost advantages of decreased downtime from producing parts without stopping are compounded by a reduced need for machine reconfiguration and testing. 

Faced with an inefficient reliance on batch production last year, GLT Inc. (Dayton, Ohio), a source of precision CNC machining, welding and assembly, decided it was time for a change. GLT opened as a warehousing firm in 1987. By 2002, however, the business had expanded into three facilities for assembly, kitting and machining. “GLT was buying a lot from machine shops, so the owner decided we should start our own machine shop,” says Jason Heggs, manufacturing manager for GLT. Mr. Heggs came on board at that point, and three machines were quickly purchased. After 16 years that number has expanded to 31 spindles and focuses on horizontal, vertical and lathe turning.

In 2007, the company was bought out by Kevin Knight, Chris Knight, Jeff Banford and Brad Labensky (the vice president of operations). Today, GLT does a multitude of machining—including castings, weldments—and from raw stock including long, skinny stainless steel parts for commercial equipment used in the food service and grocery industry. The shop has 60 employees, with about 35 working in the machine shop. Mostly, it only runs first and second shifts, although machines can run overnight with operators coming by every four hours or so to check on them.

These two daily shifts were producing 600 long rods for a customer with one operator on a Mori Seiki SL 25, a 30-year-old standard turning center lathe the company had purchased around a dozen years earlier. This process, however, involved paying $35,000 a year for an outside saw operation to cut bars to length. When the cut bars were returned in batches, an operator would manually feed them into the turning center all shift long. “It’s the same operation on both ends, and it’s a 20-second cycle time,” Mr. Heggs says. “The poor guy would have to take the conveyor rod and spin it around, and do that all day.”

This expenditure of time, labor and money wasn’t allowing the company to stay competitive, so a decision was made in 2017 for GLT to reach out to distributor Advanced Machinery Companies (AMC). Started in 1978, AMC is a full-service machine tool organization, located in Dayton, Ohio, that distributes and installs new and used CNC machines. AMC’s answer for GLT was an RB20Y Swiss-type CNC lathe from Swistek Machinery America, which offers packaged machine configuration systems.

The turning center has a tooling system that features eight external and five inner toolholders and accommodates as many as seven side drilling devices. It also includes a FANUC 32i-B control system, revolving guide bushing, removable guide bushing for short parts, part catcher, part conveyor, chip conveyor and a cart. As well, Swistek recommended a Hydromat Edge Technologies Scout 320—an automatic magazine-style bar feeder designed for feeding round, square and hexagonal barstock in lengths up to 12 feet, with a diameter range of 3 to 27 mm. 

The machine was installed by Swistek in December and was up and running by early January. Swistek shipped it to AMC, which then rigged the machine in GLT’s machine shop. Then Swistek sent a technician in who spent a week with GLT setting up the CNC, programming it and training the supervisor. “It’s a little bit of a different animal than what we’re used to, machining-wise,” Mr. Heggs says. “The technician was very thorough, though, and Swistek has been a great support since. Whenever we call or email them, they get back to us right away.”

Now GLT is running continuous production, making 1,000 parts across the two shifts. The bar feeder loads full-length, 12-foot bars in, and after every cycle the machine cuts them down. “It comes in and does the front side, pulls the part, parts it, and then while it’s doing the front side, it does the back side too, and then ejects the part,” Mr. Heggs says. Consequently, continuous production has completely eliminated the outside saw operation.

Any new addition like this isn’t necessarily seamless. “There have been some growing pains,” Mr. Heggs says. One issue GLT had to get used to is tooling life. The way the Swistek operates, even if a cut-off tool breaks, the bar feeder will continue to feed the machine. When the tool moves aside, this can bend the bar into an S shape, which has resulted in more than a few destroyed collets. GLT has, however, been able to adapt. “We get about 5,000 parts per insert, so every 4,000 parts we change all our inserts to try to avoid that,” Mr. Heggs says.

GLT hopes this transition away from batch production into continuous production is the start of a new direction for the shop. It has mostly been doing short-run production, with 500-1,000 pieces as the norm, but Mr. Heggs hopes to expand to more long-run production. “We’re going to do as much bar feed as we can and are looking into implementing robotics,” Mr. Heggs says. 

But the company is doing a lot of both milling and turning, so it is looking into mill-turns and has also explored additive manufacturing, having taken seminars at the University of Dayton. “We’re always looking to eliminate operations,” Mr. Heggs says. “The less time a part is handled, the less often it can be loaded incorrectly.”  

GLT Inc. 937-237-0055. gltonline.com. 

Advanced Machinery Companies, 937-278-7337, advancedmachinery.com

Swistek Machinery America, 203-301-4848, swistek.com