Busting A Bottleneck

"Business is booming right now, and without the Makino MMC and the A100E machining centers, we'd have a hard time keeping up. Fortunately, we invested at the right time and are ready to handle business as it comes in the door."

"We had a definite bottleneck in our shop," says Gregg DeCheck, manufacturing engineer for Twin Disc of Racine, Wisconsin. "We knew why the process was being held up - old machinery that couldn't keep up and forced us to re-work parts."

Twin Disc was experiencing first-hand a problem many other shops in the U.S. are struggling with. A particularly important process was hindered by worn-out, inefficient equipment.

"A bad part won't leave our shop," says Tom Mutter, CNC tool operator for 33 years for Twin Disc. "Not only were the old machines slow, but we'd have to prove parts two and three times to make sure they were right. It really slowed down our progress.

"On top of this, we had very limited flexibility. We couldn't stop what we were doing to start urgently needed parts. The person in need would just be out of luck."

"We knew we needed a fix," adds DeCheck. "More importantly, we knew we needed a reliable, efficient process upgrade that would allow us to cut parts for years without any issues. We choose a Makino MMC with two A100Es to bust our bottleneck."

Making Things Work

For 87 years Twin Disc has been developing, engineering, manufacturing and distributing power transmission products that make things work. The products they produce are seldom seen, but go into machines that contribute to the high standards of modern life.

Twin Disc products are installed in the drivelines and powertrains of farm tractors, road pavers, cranes, mining trucks, oil rigs, logging equipment, firefighting and rescue vehicles, pleasure craft, fishing and work boats, pumps, turbines, and many other products. The company takes great pride in the fact that they help feed us, provide natural resources, build our cities and homes, transport us, defend us and influence our lives daily in many unnoticed but critical ways.

Most of these products manage and control the horsepower generated by internal combustion engines and electric motors. Where there's an industrial strength vehicle or machine that requires converting horsepower to productivity, Twin Disc has a way to do it, and has helped put the world to work for nearly a century.

This experience has made Twin Disc a well-oiled manufacturing machine, cranking out thousands of parts each year for customers with demanding specifications and schedules. With many of their customers beginning to demand customized parts, and some requiring parts in a JIT (just-in-time) manner, Twin Disc found their process slowing down at one particular point - the machining of transmission housings.

The Bottleneck

"It was common knowledge that the housings were holding up everything else. Until the housing was complete, all other processes had to wait. For a company like ours that is so experienced at manufacturing, a bottleneck is unacceptable," says DeCheck.

The transmission housing setup was a simple one - two machines with two operators, each loading castings onto fixtures. There were six pallets of parts, all loaded into the machines as they were ready to be cut.

After the part came off, it would go to layout where it was checked for accuracy. Often, they'd have to put the part back on the machine at least once to fix imperfections - re-setting up the part, running a partial program to fix the flawed cuts, and then re-checking the part for accuracy.

When everything on the part finally checked out, it would be sent down to the next stage.

"The old process was a pretty static one. If a request for an urgent part that was not already in progress came in, we were stuck," says Mutter. "The process took so long and was so labor-intensive we couldn't afford to push parts to the head of the line unless it was absolutely necessary."

This lack of flexibility left Twin Disc unable to get ahead of production on the transmission housing, which meant the additional processes, such as gearing, were forced to wait on the housings.

"Hence the bottleneck," comments DeCheck. "We were always waiting on the housings to be done before moving on. This became especially frustrating when a customer needed a custom part urgently. The lack of flexibility meant we'd have to sacrifice other parts to get the custom part done quickly."

Machining Solutions

"We knew the old machinery was costing us time and money," says DeCheck. "As a fix, we tried to have one of the machines rebuilt. It didn't work like we hoped.

"The rebuild threw off the perpendicularity of the machine, making a bad problem even worse. The old machines just wouldn't do what we needed to make the parts quickly and efficiently, while maintaining our high standard of quality."

Twin Disc looked at many manufacturers' machines to replace their worn-out equipment. They focused on ROI (return on investment), reputation and the financial stability of the manufacturer.

"We didn't want to buy a machine that the manufacturer could disappear tomorrow, get rid of their line of machines, or do anything else that might jeopardize our ability to manufacture parts," says DeCheck. "We knew Makino by their reputation of reliability, accuracy and customer service. And we knew Makino wasn't going anywhere, so they'd be around for the future for service, upgrades, and new machines."

Twin Disc ended up purchasing a Makino Machining Complex 2 (MMC2). The machining cell consisted of 22 pallets (11 per machine) and two A100E horizontal machining centers, each with a 244-tool magazine.

The A100E's cutting feedrates and rapid traverse rates are 1,970 ipm (50m/min). It comes standard with Makino GI control feature that allows for high feedrates and superior accuracy.

The MMC allows Twin Disc to load several parts onto fixtures, and then have the machine automation do the rest of the work. All the operator has to do is load/unload parts.

Big Transmission

"We have one really big transmission housing that demonstrates the advantages of the new setup well," says Mutter. "The housing starts out as a 1600-pound casting. The final piece is four and a half feet tall, four feet wide, and two feet deep.

"We have many processes to get this part done, including boring radial holes, milling mounting pads, drilling and tapping. We semi the bores first, then drill and tap all the faces. We mill and finish-turn a pilot diameter on the back where the front housing bolts up to."

"We also use techniques such as circular interpolation and helical milling so we don't have to use very large boring bars," adds Mutter.

"This big guy has bores 22 inches deep. It's big and complicated, but we've reduced the process time down from 14 hours to seven hours with the MMC and the A-Series machines."

Tool Usage

"One tool we use to do deep bores is a 21-inch mill with a special shank to cut down on vibration and chatter with the tool. We cut all the 21-inch counter-bores with that tool on the A100Es.

"We use two state-of-the-art mills on nearly all the cuts, which allow us to run at a high RPM and feedrate, taking off about 200 thousands of stock per pass. Our old machines didn't let us use this modern, highly efficient tooling. This cuts down production time significantly."

"Next we do the finish work and drilling/tapping," explains Mutter. "Again, we run high-performance drills at high speeds, which is considerably faster than standard milling. After we're done drilling and tapping all of our holes, we do the finish boring."

The entire process takes just seven hours using the Makino Machining Complex and A-Series machines, a 50 percent reduction over the previous time.

"As far as quality goes, all first-pieces off the machine are checked," says Mutter.

"We check every bore and spot check caps and some of the other processes as it is running. The quality we're getting is excellent. We run some government work that is very tightly spec-ed, and with the Makinos we're often seeing perfect parts. That's pretty hard to believe from where we were coming from with the older equipment we replaced.

"One of the biggest problems we ran into on the old setup was deep perpendicular bores, maybe five or more inches deep, where we'd have to hold a couple of tenths perpendicularity per inch. We couldn't pull that off on the old machines, but with the A-100Es, we're getting it right every time."

Busted Bottleneck

"We've experienced a 30 to 40 percent decrease in cycle times on the housings, most of which came from reduced setups and faster feedrates," says DeCheck.

"We've been able to have operators double-up on machines, too, which saves a lot of time and money. We used to have to assign one person to each machine, but because we don't have to pull the part off the fixture for each new piece we put in, one operator can now handle two machines."

Twin Disc used to have two six-pallet machines dedicated to gear housings. These machines each had an operator, standing by to pull finished parts off the fixture and replace it with a new part to be machined, then pull the part off and take it to layout for proving.

Twin Disc is finding savings in areas they did expect, such as machine uptime and cycle times. And they are also saving time and money in areas they didn't expect, such as tool life and tool changes.

"One of our primary concerns was reducing the amount of machine down- time," says DeCheck. "Our older machines were ready to be retired, and reminded us of that fact often by going down all the time. When we went to look for a new CNC tool, we wanted something that would run reliably. Makino's reputation for reliability was something we were very interested in and has proven true.

"The 22 pallets allow us to cycle parts much faster, allowing the machines to keep cutting instead of stopping to have operators constantly load/unload parts. Our

feedrates have improved by 25 percent. The new machines have increased our ability to feed from 158 inches per minute to well over a thousand inches per minute, though we don't run them quite that fast all the time."

"The high-pressure coolant allows us to get better tool life and easily flush chips from the holes," comments DeCheck. "The new boring tools allow us to save space in the magazine

- we can cut most of the bores with the tools on board. Because of this we can often mill-bore where we'd have to hand-bore in the past, which is a very expensive and time consuming process."

"It's important to our company that every major purchase have a clear ROI (return on investment)," adds DeCheck. "We had to see how spending the extra money on a premium machine would benefit us quickly, as well as in the long-run. Because we were able to have one operator on two tools, from one-on-one, and because our speed improved by 30 to 40 percent immediately, ROI wasn't hard to establish."

Short Runs

Finally, short runs are now possible. "Being a custom transmission shop, everything is different and everyone wants something different. We now have the ability to switch from job to job on demand," says DeCheck.

"We might be in the middle of a run and someone would need a different housing. In the old setup, the person needing the housing would be out of luck. Now, in a matter of a few minutes, we can make a quick change and run the job. They don't have to wait for castings anymore - it's moved the bottleneck down to the next stage of the process."

"We can have the parts sitting on the rack, have several orders opened and in partial operation, and we can switch back and forth between any of the orders open at the time. Give them two pieces of one, one of another, whatever they need at that moment," adds Mutter.

"We're running parts so fast now that we're having problems keeping up with supply of castings - we cut them faster than we can get the raw pieces to cut."

Eliminating Future Bottlenecks

"We're looking into buying more machines to improve other processes in our shop, hope-fully eliminating other bottlenecks in the process," says DeCheck. "We're slowly moving more towards a JIT (just-in-time) scenario, as long as the equipment and people to support that are in place.

"Business is booming right now, and without the Makino MMC and the A100E machining centers, we'd have a hard time keeping up. Fortunately, we invested at the right time and are ready to handle business as it comes in the door."

For Twin Disc, the improved cycle times, dramatically improved reliability, added manufacturing flexibility, and reduced labor adds up to tangible savings, everyday.

"The Makino MMC and A-Series machines have eliminated our bottleneck," says DeCheck. "This technology has helped show us what new equipment can do to improve our manufacturing process."

Twin Disc
Racine, Wisconsin
Phone: 262-638-4000
E-mail: [email protected]
Web: www.twindisc.com