Special delivery

Feb. 1, 2001
Made-to-order tooling can send profits straight to the bottom line.

Made-to-order tooling can send profits straight to the bottom line.

Although special tooling can help slash cycle times, lower scrap rates, and improve part quality, many shops still opt for standard tooling, which is often less expensive and more readily available. However, these shops may really be missing out in the long run, suggests Gary Wysocki, a project manufacturing engineer for Hamilton Sund-strand Corp. of Windsor Locks, Conn.

On just one job, his company slashed holemaking costs 94% by switching to a specialty drill. The tool may have cost more than standard tooling, but it quickly made up the extra cost in increased production. And Hamilton Sund-strand never had a problem with on-time delivery.

The job, making holes in cast aluminum for an actuator, required seven separate standard tools at a cost of $527. The aerospace manufacturer wanted a special drill in a permanent machine setup that would cut overall tool cost, increase toolchanger capacity, and improve part quality.

Hamilton Sundstrand eventually purchased a custom-manufactured K40 carbide G drill from Guhring Inc., Brook-field, Wis. This 7-in-1 tool, mounted on a Matsuura horizontal machine, replaced a taper length drill, a counterbore, a port cutter, a reamer, a countersink, and two spot drills.

While the Guhring tool's price was $611 — about 16% higher than what it had been using Hamilton Sund-strand quickly recouped the tool's price and more. A 3,600-hole test of Guhring's 7-in-1 versus the seven separate tools found that per-hole costs dropped from $5.66 to $0.33. The 7-in-1 saved Hamilton $19,203.79, as total cost fell to $1,187.53 from $20,391.32. In addition, total cycle time was reduced 92%, from 130 to 10.5 sec. Also, regrind costs during the test were $0.00 for the 7-in-1, which lasts for 5,000 holes, while the separate tooling cost $1,908 in regrinding.

"It's all cycle time," says Wysocki. "You're investing more money up front, but the pay-back in terms of tool setup, machining time, and tool life more than offsets that."

What's more, the 7-in-1 tool greatly reduced the potential for machining error, resulting in a part that meets tight tolerances. According to Wysocki. "The hole size is perfect, and the quality of the hole from the G drills is well within spec as far as size and concentricity goes."

But just as important as these cost-savings and performance benefits is the quick delivery of small special tool orders. After all, shops can't benefit from a specialty tool they don't have. That puts pressure on their suppliers to have the drills ready when needed.

To ensure that customers such as Hamilton Sundstrand get their tools delivered on-time, Guhring is building a network of small, highly automated factories around new proprietary grinding stations designed and built by the company. The grinding stations, called US 125/135s, turn out small lots of just-in-time, high-quality tools.

Jobs that once required four separate machines and four operators can now be done on a single CNC machine manned by one person. Machine setup data, blueprints, and part programs are stored electronically, speeding setup of repeat orders.

The grinding stations are really standalone manufacturing cells, providing one-stop production. They can turn a centerless ground blank into a finished product using just one chuck. While blanks must be loaded and finished parts unloaded in the 125, production is automated in the 135, which is equipped with a magazine that feeds blanks and removes finished drills.

Eliminating multiple-machine setups minimizes operator error and scrap. And one-chuck machining means the company can hold tight tolerances throughout production.

Eventually, Guhring will build a network of US 125/135s so that tool data can be sent from one machine to another. That way, a tool built in Brook-field could be quickly reproduced in Detroit by downloading information from one grinding station to another.

The grinding stations have 10 machine axes, all under CNC control. An automatic tool-changer with up to nine programmable HSK grinding-wheel hubs gives the machines the versatility to make everything from small drills to tools up to 20 mm in diameter and 300 mm in length.

The US 125/135s will pump out tooling for companies like Hamilton Sundstrand as well as other Guhring customers, such as the automaker Honda. Currently, Guhring supplies Honda of America's engine plant in Anna, Ohio, with 500 different special cutting tools, mostly used to cut aluminum engine blocks. On any given month, Honda may order 50 different designs, often with lot sizes of less than 20 pieces.

While the quality of Guhring's drills was never an issue, Honda was once concerned with its delivery schedules. Karl Schimmoeller, staff engineer for Honda of America's engine plant in Anna, says that five years ago Guhring's delivery times were as long as 20 weeks. But in recent years, Guhring has shown dramatic improvement, reducing leadtimes on specials to 7 weeks or less and hitting all its deliveries.

An extra technological edge

A new coating technology is helping Guhring extend the life of both its standard and specialty cutting tools. The company, which several years ago introduced Movic and Firex coatings, recently introduced MolyGlide, a dry, thin-film integrated lubricant based on molybdenum disulfide and 14 other alloying elements. Together, they act like a gliding agent, greatly reducing surface-to-surface friction and subsequent wear on tools or parts.

MolyGlide is a soft coating and, when applied over a hard coating, provides the optimum combination of heat-resistance and lubricity necessary for dry and near-dry machining. Its friction coefficient against steel is only 0.05 to 0.15, compared to 0.4 for titanium-nitride hard coating and 0.20 for tungsten-carbide-carbon soft coatings. The coating is not soluble in water, so it can be used with both conventional coolants and oils. It withstands heat up to 1,470°.

A MolyGlide coating protects tools that cut aluminum, aluminum alloys, alloyed steels, nickel alloys, titanium alloys, and copper. The coating fights edge buildup and packing in drilling, tapping, reaming, milling, turning, broaching, hobbing, and many other cutting operations. It also prevents galling in forming, punching, and stamping operations. MolyGlide-coated tools are well suited for difficult-to-lubricate applications, such as deep-hole and small-diameter drilling/reaming and tapping.

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