Automate and separate

Feb. 12, 2009
In TNT EDM’s milling machine room, the shop specializes in 5-axis machining and hardmilling of parts. At TNT EDM Inc., success hinges on working smarter, not working harder. The Plymouth, Mich., jobshop gets about 60 percent of its work ...
In TNT EDM’s milling machine room, the shop specializes in 5-axis machining and hardmilling of parts.

At TNT EDM Inc., success hinges on working smarter, not working harder. The Plymouth, Mich., jobshop gets about 60 percent of its work coming from the automotive sector, runs more than a third of all its jobs in lights-out production, and has most of its machinists running multiple machines simultaneously. Machinists run as many as 10 machines or more at a time.

Automation plays a critical role in TNT’s “working smarter” game plan, as does the way the shop arranges its machine tools.

“We have changed the way we approach jobs,” Tom Mullen, president and owner of TNT EDM, said.

“For example, with EDMs, we realized that jobs typically involve multiples – either multiple pieces or multiple burn areas. By incorporating robots, we can accomplish both. Instead of running one or two pieces of a job on a machine, we may run 50, and change them using a robot. With large parts requiring multiple burns, we always try to do them all in one setup.”

EDM automation at TNT EDM consists of tool/electrode changers and workpiece and pallet changers. A large portion of such automation can be found tending the shop’s Mitsubishi sinker and wire EDMs.

“When we look at a job, we think of how we can automate it. Even if jobs just to take the operator out of the equation. Automating is part of working smarter, and it doesn’t always involve a robot.

On one of the shop’s jobs, an operator was running two parts simultaneously. The shop re-thought the job and built a fixture that holds 10 pieces. The operator now runs four of these fixtures at a time – a total of 40 pieces. TNT EDM actually does the job for less than it cost the customer to do it in house.

Mullen said it is that kind of thinking that makes the shop competitive. But, he mentioned that once an EDM is automated and pretty much running around the clock, the only way to increase capacity is to add more machines, which is what his shop did.

TNT EDM keeps its Mitsubishi sinker EDMs in the shop’s “sinker” room loaded with electrodes and workpieces using automated robots.

TNT EDM started out as an EDM house doing strictly mold work, but after about four or five years, Mullen realized that the only way to grow the business was to expand its capabilities beyond EDM. There weren’t a lot of customers that wanted the shop to do just the EDM work on a job.

And while TNT EDM is still a premiere EDM house, it now has more milling, turning, grinding and inspection machines than EDM equipment. With this added capability, the shop has been able to win work in the aerospace, land-based power generation and medical industries.

Nowadays, some jobs don’t even make it to TNT’s EDMs, Mullen said. Instead, the shop may use five-axis machining or hardmill parts after they’ve been hardened.

“If we hadn’t taken the gamble to buy the equipment we did about seven years ago, we’d be dead in the water as far as winning new work is concerned. We can now go after the parts that are complex, hard to program and difficult to process. We can’t just machine square blocks and expect to be competitive,” Mullen said.

As TNT EDM acquired new types of machine tools, it arranged them in such a way that would allow for working smarter, not harder.

Within TNT EDM, there are, for the most part, 13 shops within a shop, and types of machines are separated and segregated into individual rooms. The sinker EDM room is separate from the hardmilling room, as is the wire EDM room separate from the green-machining room and the grinding room. While this may not be how most shops organize machines, Mullen said he gets a lot more output from his arrangement.

Automated robots also tend Mitsubishi wire EDMs in TNT’s wire-EDM room.

His logic is “do what you do best and forget the rest.” For example, the guys that run the wire-EDM room program and run only wire EDMs. They aren’t operating sinker EDMs or milling graphite for electrodes.

“All the different machines are in their own rooms, and the work comes to them. At one time we had six similar types of EDMs located in six different areas of the shop, with five separate operators running them. Now, we have 15 of the same type of EDMs in one room, and two people keep them all working,” explained Mullen.

The shop blasts through much more work with one guy running 10 or so machines as opposed to the same guy running one wire EDM and one sinker EDM, for example.

“For us, and I believe so for the overall job shop environment, the cell concept does not work. Cells mean you have to have one guy that knows how to run, for example, an EDM, a milling machine, and maybe a grinder. And being able to effectively process all that those operations entail is just too much,” Mullen said.

TNT EDM automates wherever possible, including these Roku Roku vertical milling machines.

With TNT EDM’s machine arrangement, parts that require operations on different types of machines travel from one room to the next by way of carts. And whether it’s 5 parts or 100 parts, all the parts of a job stay together and are not scattered around the shop at different machine locations.

Parts move to one area/process, get signed off on from that area, move to the next process area, are signed off on, and so on until completed.

Mullen said there is nothing better than a visual – all the parts for a job sitting on a table – to find out exactly what stage a job is at in production. And, most of the shop’s parts weigh 5 lbs to 20 lbs, so transporting them around the shop is no big deal.

TNT EDM will continue to develop into a flexible job shop.

“Our work is changing. We started out with only EDM, and now our 5-axis and other milling machines can out work our EDM equipment. To complete the shop, we will invest in waterjet and laser cutting machines. This flexible fabricating equipment will move us into new markets and help us to continue growing,” said Mullen.

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