June 2008 Edition

CUTTING TOOLS

Carbide to the Rescue

A carbide end mill that finished the job in two hours, instead of three-and-a-half days, ended a backlog for an oil industry manufacturer

Coming in as a new manager to a backlogged shop can be an intimidating experience, but as a veteran in the business, Pat McLaughlin was unafraid when he took the reins of Machining and Manufacturing, Houston, TX, a MIC Group subsidiary. Instead, he looked for ways to improve profitability and delivery to customers. McLaughlin was the equivalent of the cavalry riding to the rescue.

M&M makes large parts for the oil industry, mostly in forged 4140 and 17-4 stainless steels and Inconels. However, with 22 machines and 28 employees, the shop was running a single eight-hour shift every day with a daunting production backlog.

One particular backlogged product was a large cylindrical flapper housing, 30" diameter by 36" length, in 17-4 stainless forged to 42 to 44 HR_C. Designed for sub-sea applications on oil rigs, flapper housings have to withstand the corrosive effects and stresses of the undersea environment. Nature is relentless so the housings have to be replaced often on a regular basis.

McLaughlin said the problem was obvious when he looked at lead times.

"Forging requires a four-month lead time, and manufacturing time is about 10 weeks. It’s a pretty complex part."

Three Problems, One Solution

The job begins by removing a lot of material, shaving metal to a 0.500" depth, totaling 505 in³ of material removed around 2,525" of the exterior. To achieve this, M&M used a 3-flute 1" indexable mill with rectangular inserts with two cutting edges each on a 30 hp DMG running at 1,337 rpm with flood-type coolant.

The first problem was that almost half the time on that machine was unproductive.

"We weren’t even getting fifteen minutes of cycle time between indexing," McLaughlin said. "Every time we indexed, it took about 10 minutes," he said.

The second problem was that the operator was running through inserts almost as fast as it took to replace them; the inserts’ shallow cutting depth required five passes.

"We were only taking 0.100 with each pass," he said. "Due to the lead time, we sometimes had to use a different machine, and on the other machine it cut even less per pass."

Finally, the overall machining operation for one part took three-and-a-half days. So M&M could ship, at best, only three parts every two weeks.

The solution arrived with a chance visit by Pat Vroenen, an IMCO sales rep with Tooling & Accessories Group, Inc., Omaha, NE, who recommended a pow·r·feed M90 end mill from IMCO Carbide Tool Inc., Perrysburg, OH.

A Dramatic Difference

Vroenen had been making sales calls at M&M when the company was having a problem with the part.

"I showed Vroenen what we were doing, and I asked him, ‘What do you have that would fill this void?’ He said he had something we might want to try," McLaughlin said.

Vroenen arrived the next day to run a test with a different tool – the 5-flute pow·r·feed M90 end mill, the newest end mill from IMCO, a manufacturer specializing in precision rotary cutting tools.

"I knew this was a job for pow·r·feed; it’s exactly what the name suggests," Vroenen said. "I’d seen customers get much higher feed rates at higher speeds with the original 4-flute, and the new 5-flute is getting even better feeds. M&M works in some tough materials, but the machine would fly through those, no problem."

As the shop prepared for the test, Vroenen gave setup instructions to the programmer.

"He thought I was crazy when I first gave him the speeds and feeds," Vroenen said. "But, once the run started, the difference was so dramatic that everyone on the shop floor came to watch.

"As it was running during the first hour, everybody was quiet, and the machine itself was quiet," he said. "They couldn’t believe how quiet it was and how fast it was cutting."

Within two hours, it was done – the same job that used to take them three-and-a-half days and 10 tool replacements

Within two hours, it was done – the same job that used to take them three-and-a-half days and 10 tool replacements. And, the pow·r·feed tool was still in viable condition.

"We’re switching to carbide end mills because you can push them so much faster," McLaughlin said. "The end mills just hold up so much better. The wear on them – we could probably get two parts per tool with the pow·r·feed. I’m not going to push that, but you could do it. I send them out and have them reground."

And, It Improved Other Projects Too

Discovering longer tool life and repeatable savings is a common revelation after shops try a premium carbide tool, Tim Elfreich, regional sales manager with IMCO, said. He sees it time and again in tests IMCO conducts in customers’ machine shops under actual work conditions.

"Companies try to save money by buying low-cost tools, which is understandable when you’re trying to keep costs down," Elfreich said. "But, they’re increasing their tool costs, because they have to buy multiples to equal the life of one really good carbide tool."

According to Elfreich, a better tool also saves time because of fewer tool changes, and the shop has less nonproductive time.

McLaughlin agrees.

"It’s made a huge, huge impact as far as delivery to the customer, profitability, and our backlog," he said.

Since that first test, M&M has tested IMCO carbide tools on other jobs and cut cycle times on smaller, less complex parts as well.

One of those parts is a wire cover, also made from 17-4 stainless for sub-sea application. Another of the shop’s consistent orders, this job involves cutting a 0.5" wide slot at a 0.1" depth of cut to form a loop 270" around.

Vroenen suggested a test using a 4-flute coated pow·r·feed in place of the shop’s general-purpose 4-flute end mill, and running the job on the same machine with the same width and depth of cut.

"I’ve seen test reports where a 4-flute took a 29 percent larger chipload in 316 stainless," Vroenen said. "It was perfect for this job, a no-brainer."

In fact, it more than doubled the chipload of the coated general-purpose end mill, taking 0.0018" versus 0.0008" per tooth. The operator was able to more than double the rpm – 2,101 from 955 – completing the job five times faster.

"The carbide tool lasted three times longer than our old tool, so we now get three parts per tool instead of one," McLaughlin said. "We were impressed."

With these productivity improvements, McLaughlin is looking forward to working through M&M’s backlog.

"We’ve identified four or five more projects where we’ve gained time savings, and we can probably find at least four or five more," he said. "We’re looking at a lot of IMCO end mills. We’re testing and using a lot of carbide end mills to help us improve our numbers." IMCO Carbide Tool, Inc.

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