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Heat treatment boosts tool life.

Sometimes, snake oil works. Consider these before/after tooling examples:

* A machine shop, using a HSS drill to enlarge 0.062" holes to 0.076" in 302-stainless tubing, got four to six holes per sharpening, two to four sharpenings per drill before losing size. After a proprietary heat treatment, the company gets 20 to 30 holes per sharpening and holds drill size for the life of the drill.

* A tool-and-die shop, using a pierce/parting die and HSS perforators on 0.020"-thick spring-steel sheets, got 30,000 pieces per regrind. After treatment, it gets 75,000 pieces per grind and punches last 3.5 times longer.

* A manufacturer, using HSS thread chasers on Inconel, got 4 to 6 hr per grind, four grinds per tool set. After treatment, it gets 16 to 20 hr per grind, eight grinds per tool set.

The heat-treatment process that achieved these results is simple: a short dip in a hot bath of proprietary chemicals, followed by air drying. So, what's the trick-how are you changing the tool's metallurgy? Answers Bill Goodwin, president, The Solvenite Process, Roselle, IL, We don't really know. We like to use the term 'densify.' We densify the steel by penetrating 0.064" deep into the substrate with our chemicals. Unlike nitriding and other processes, there's no surface build-up."

Most small pieces are treated in 2 hr. A large die-a 2-ft cube, for example-might take 24 hr. Any hot-worked steels can be processed, always staying slightly below the material's tempering temperature, but never processing anything below 900 F.

The Goodwin family developed the process by experimenting with various "recipes" and giving treated tools to friends and local companies to try out. A metallurgist at Mercury Marine used macrophotos of a treated tool to establish the 0.064" depth of penetration.

The only visual difference of a treated part is an oxidation effect-a mottled brown appearance-from cooling in air. The larger the part, the longer the cool-down period, and the greater the discoloration. They have since added a glass-beading clean-up option for appearance purposes. (It is always a question of whether to use the tool's changed appearance to reassure people that the tool was actually treated or to clean it up and create suspicion that nothing was done to the tool, Mr Goodwin says.)

Can't anyone dip a sample out of your tank, have it analyzed, and steal your recipe? "Some have tried that," Mr Goodwin admits, "but failed to figure it out. I feel good that people are trying. Even if they knew what chemicals we were using, they couldn't get them in the right proportion. Metallurgists have examined parts to see if something physically changed, but they never shared that information with me. The true test, of course, are the results you get in production."

Although the best results were a 1000% improvement for gear hobs cutting brass, more typical is a 300% boost in tool life. Properly resharpened, the Solvenite benefit remains on the tool's leading edge, so there's no need to reprocess a tool. Says Mr Goodwin, "A gear-cutting hob can be ground all the way back to the center bore and still have Solvenite on the teeth. That's why we feel our process is a lot better than titanium nitride that has to be reapplied when the TiN coating wears off.

"We've had some of our tooling outperform carbide in interrupted cuts where carbide chips out. On the other hand, sometimes a customer sends me a dull tool to treat, and then grinds the incorrect rake on it and blames me because it did worse than before."

Many of his customers aren't talking, he says, for fear of giving away their "cutting edge." Some even deny using Solvenite to throw their competitors off the track.

So, why not give away the first tool treatment free to get new business? "That doesn't usually work," Mr Goodwin explains. "If it's free, management doesn't feel it's worth assigning someone to watch the tool to measure the change in performance. When I charge for it, people are more inclined to pay attention and record any change."

Mr Goodwin charges by the pound. "HSS cutting tools under 1 lb are $7.20 each. Tools over 1 lb are $7.20/lb, with special prices for hobs, broaches, and chasers.

Satisfied user

Al Lavezzi, president, Lavezzi Precision Inc, Elmhurst, IL, has been using the Solvenite Process for 20 years. "We treat any of the high-speed tools we use. So far, we've treated about 4000 flat-form tools, and it doubles the life of any tool we use. It does wonders with high-speed end mills. It's a fantastic process."

Mr Lavezzi feels it is simply a through-hardening process. "It hardens the part without making it so brittle that it chips. We make a lot of special milling cutters for our own in-house use and easily double their life. It also does a nice job with 300-Series alloys. If you can't use carbide and have to use high-speed steel, there's no question it improves the life of the tool and is well worth the cost of treatment.

"We put a lot of small holes in titanium medical parts, and it does a nice job of keeping these tips sharp. If the drill is too small-under 0.040"-you can have a thermal-distortion problem with the Solvenite process. That's the only negative we've experienced.

"Over the years, we've read about various treatments and spray coatings and tried most of them, but this is the only one that we've found we can really depend on."

For more information on The Solvenite Process, Roselle, IL, circle 377.
COPYRIGHT 1992 Nelson Publishing
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Copyright 1992 Gale, Cengage Learning. All rights reserved.

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Publication:Tooling & Production
Date:Mar 1, 1992
Words:939
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