Ever Considered Making Your Own Tools?
Whether you use a lot of cutting tools, or sometimes find yourself desperately lacking the right tool, you've probably considered making your own. Or at least sharpening your worn tools. But how do you decide if taking tool grinding in-house is the smart decision? It's a question GKN Aerospace Engine faced, and Principal Manufacturing Engineer Jeremy St. Pierre walks us through their considerations. Plus, he offers priceless advice on best practices if you make the leap.
Jeremy St. Pierre led the creation of an in-house tool grinding operation at GKN Aerospace Engine that paid for itself in only 2 years (Image provided by ZOLLER)
CNC tool grinders and the required ancillary equipment represent a significant investment. So, GKN's management asked St. Pierre to study their tool consumption and project the potential savings they could achieve by taking tool grinding in-house.
One key factor, explained St. Pierre, was the fact that many of their tools can be reground multiple times. For example, he pointed to their many tapered ball nose end mills, which can be sharpened to the desired "true form, every time."
Conversely, St. Pierre cautioned, many of these tools are complex, with unequal indexing and variable helices, so many outside vendors do not want to regrind these tools unless they made them originally. So, if you can't regrind them yourself, you're locked into a limited supply, which is a costly and potentially risky place to be.
On a standard tool, GKN goes through 22 to 30 different parameters. But they make a lot of variable index, variable helix tools, so they have to check every flute, especially on a setup.
St. Pierre also found that some of their high-volume tools were very expensive just because they were not standard in the industry.
"Instead of having a half inch cutter, we might have a 0.485" cutter diameter. Because that technically is a custom, we were paying a premium and ordering 12 weeks of tooling. And we had long lead times."
By calculating their true cost of tooling, including the frequency with which they had to "send out 70 tools at once to get a good price," St. Pierre was able to make a strong case for investing in an even more capable tool room than originally envisioned, with four ANCA MX7 Linear tool grinders, a ZOLLER Titan measuring machine, and a full complement of support equipment like a wheel dresser and a drag finisher.
Yet the payback time turned out to be just two years.
VIDEO: ANCA's MX7 Linear Machine
Having said that, St. Pierre recognizes that GKN is a large company that spent a fortune on tools, so starting smaller makes more sense for many companies. He also suggested taking a close look at the "easy wins," the tools that are both important and doable, "before you say, 'We can bring in everything.'" Then you can confidently specify the grinder and associated gear and see if the numbers work.
Faster Turnaround
St. Pierre's tool room significantly improves GKN's overall efficiency simply by delivering the tools the production floor needs quickly. And it's not just regrinds.
"We're currently using the ANCA machines to grind everything from one-eighth inch diameter tools up to one by eight inch, with a five-and-a-half inch length of cut," explained St. Pierre. "We do a lot of one-off custom tooling and whatever emergency repairs are needed. Any tool that can be made outside, we now make. We make composite tooling, special material tooling, tooling for plastic, wood...whatever we need to do. Lead times for custom tools are as little as one day," he added, and a maximum of 2 weeks. "And if you want just one, we make you one."
Tweaking Designs to Improve Machining
You might think that an in-house grind shop wouldn't make better cutting tools than the specialized manufacturers. But owing to their focus on GKN, and St. Pierre's willingness to experiment, the team has in fact "beaten out a fair amount of tooling from other very well-known tool manufacturers," said St. Pierre. "Not that that's our intention. It's just that we're able to really focus on our operations and our products and customize a tool for that production environment. We have the ability to tweak tooling just for us."
The MX7 Linear is a powerful, versatile CNC tool grinder designed for production grinding. It is built to meet the demands of high output, high precision manufacturing.
St. Pierre summarizes his approach as "push things until they break and then dial it back to make that best tool." They'll try tools at the attached GKN plant if there are idle machines, or send them to their Swedish location, where they have a dedicated testing machine and can provide immediate feedback. They'll also give sample tools to companies they've worked with over the years and ask for their input.
St. Pierre also credits ANCA (based in Wixom, MI), with helping meet some of his tool design challenges. "I go to Michigan a few times a year because the trip is worth it. If I'm struggling, I usually give ANCA tools that not many people are making, and we'll sit down together and design it. Or they'll call me and we do it over the phone. Within a day or two, we'll have a tool together. And they don't ask anything for it. They just want to know how it's going. They've helped out a lot."
One surprising discovery St. Pierre reported was being able to eliminate the need for coating on many of their tools by instead honing the cutting edge in an OTEC drag finishing machine. "Our tools are lasting longer edge prepped than they were coated," St. Pierre observed.
ANCA's MX Linear range includes new technology linear motors that enable them to achieve even higher levels of accuracy and performance.
In addition to the higher performance, St. Pierre added, edge prepping also eliminates the roughly one-week lead time required for coating, plus that cost and the extra shipping and handling. "A regrind might cost $5, or $100," he continued. "But if it's a $5 regrind, it's still a $10 coating. Now you're basically at three times the tool cost. We can eliminate that with a process that takes a few seconds." (GKN's average honing time is about a minute, and the OTEC processes 25 tools at a time, according to St. Pierre.)
Independent Profit Center
St. Pierre's tool room is attached to GKN's Aerospace Engine plant in Newington, CT, but it's run as a separate profit center. They service all 7 GKN Aerospace Engine sites in North America, plus they sell tools to other local aerospace companies. They've even been able to bring in outside work for other companies to add revenue. It's a sidelight for GKN, but it's also worth considering this possibility when deciding to pursue in-house tool grinding.
Choosing the Right Grinder
If you're ready to take the plunge into tool grinding, the next most important consideration is which tool grinder you should invest in. Naturally, ease of use and support are key factors, and it's wise to think beyond the machine builder. Ask your current suppliers what machines they use and if they are willing to share programs or offer other assistance. For GKN, ANCA was a clear choice, because they're a market leader and the Swedish operation had ANCA machines.
"That way we can help each other out," explained St. Pierre. "We can send programs to each other, we're grinding the same way. If they need us to make some tools, they can send us a program, we can run the tools, ship them back, and the tools are exactly as if they'd made them there."
VIDEO: GKN Aerospace Global Capabilities
It should be emphasized that although St. Pierre had years of manufacturing and problem-solving experience when he started the project at GKN, he'd never ground a tool. That also holds true for everyone who joined the team thereafter.
"I hired people that I knew were mechanically inclined and understood the real world and how you shouldn't overcomplicate things," recounted St. Pierre. "They were all nervous at first, but the first thing we did was fly out to Michigan for two-weeks of training with ANCA. And then we started running."
They've been learning ever since, and made some mistakes, he added. But only once have they sent out a tool that failed.
Want more information? Click below.
Rate this article
View our terms of use and privacy policy ::m::