Coolant switch boosts high-end wheel machining

Author Cutting Tool Engineering
Published
September 01,2010 - 11:00am

Related Glossary Terms

  • computer numerical control ( CNC)

    computer numerical control ( CNC)

    Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

  • coolant

    coolant

    Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

  • corrosion resistance

    corrosion resistance

    Ability of an alloy or material to withstand rust and corrosion. These are properties fostered by nickel and chromium in alloys such as stainless steel.

  • emulsion

    emulsion

    Suspension of one liquid in another, such as oil in water.

  • lubricity

    lubricity

    Measure of the relative efficiency with which a cutting fluid or lubricant reduces friction between surfaces.

  • metalworking

    metalworking

    Any manufacturing process in which metal is processed or machined such that the workpiece is given a new shape. Broadly defined, the term includes processes such as design and layout, heat-treating, material handling and inspection.

  • sawing machine ( saw)

    sawing machine ( saw)

    Machine designed to use a serrated-tooth blade to cut metal or other material. Comes in a wide variety of styles but takes one of four basic forms: hacksaw (a simple, rugged machine that uses a reciprocating motion to part metal or other material); cold or circular saw (powers a circular blade that cuts structural materials); bandsaw (runs an endless band; the two basic types are cutoff and contour band machines, which cut intricate contours and shapes); and abrasive cutoff saw (similar in appearance to the cold saw, but uses an abrasive disc that rotates at high speeds rather than a blade with serrated teeth).

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END USER: Cramer Engineering Corp., (951) 549-6557. CHALLENGE: Reduce oil mist and improve machining of aluminum automotive wheels and other components. SOLUTION: A semisynthetic metalworking fluid. SOLUTION PROVIDER: Chemetall, (800) 526-4473, www.chemetallamericas.com

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Launched in 1982 as a defense contractor, Cramer Engineering Corp., Santa Fe Springs, Calif., has evolved over the years from a production shop to an aerospace parts manufacturer to a supplier of machining services for forging and custom shops that produce components for aluminum automotive wheels. The company also machines H-13 tool steel dies used to forge wheel components.

During its evolution, the shop grew from a couple of machines to 18 CNC mills and lathes, from two to 18 employees and from 5,400 to 20,000 sq. ft.

According to Owner Dave Cramer, custom auto wheels are up to 24 " in diameter and larger. As diameters increase, so does market demand for forged, rather than cast, wheels. “As wheels grow in size, there’s more need to reduce weight,” he explained. “A stronger product can be lighter, so in the high-end market there’s a lot of emphasis on forged modular wheels as opposed to cast wheels because using modular components from forged aluminum produces much stronger, lighter wheels.”

Forged wheel components account for roughly 90 percent of Cramer Engineering’s business. A long production run might involve 100 pieces, and as often as not the company machines a single set of forging dies or a set of custom wheels for one vehicle. “It makes for a lot of setups, but business has been so rough the past couple of years it’s hard to say no to someone who wants to spend thousands of dollars on a set of wheels,” Cramer said.

Despite all the changes, Cramer Engineering’s choice of metalworking fluid didn’t—until recently. “We were using a very inexpensive, soluble-oil coolant,” Cramer recalled. “It cost $2.86 per gallon. It worked fine, because when you’re machining mass quantities of aluminum you’re making small chips that carry tramp oils and other contaminants with them on the conveyor.” When machining around the clock, the shop didn’t need oil skimmers or biocides, Cramer noted. “We simply replenished the inexpensive coolant as needed.”

chemetall pro times 4 stack.psd

Courtesy of Chemetall

High-end modular automotive wheels—the bread and butter of Cramer Engineering—are made from forged, rather than cast, aluminum components.

The soluble-oil fluid may have been inexpensive to purchase, but as Cramer Engineering switched to smaller lot sizes, its shortcomings became more obvious. “We were consuming a lot of coolant—four or five barrels a month, because so much of it was being carried out of the tank,” Cramer said. “It also created a lot of oil mist, which coated every surface of the shop.”

Eventually, a representative of Chemetall, New Providence, N.J., convinced him to try the company’s Tech Cool 35052 semisynthetic fluid in one machine. According to Chemetall, the coolant’s chlorinated extreme-pressure constituents enhance lubricity, while other ingredients promote emulsion stability, bioresistance without use of biocides, corrosion resistance and detergency.

“The Chemetall rep said, ‘Try this. It won’t get carried out of the tank, it won’t go rancid, and you’ll get longer tool life,’ ” Cramer said. “Operators liked it, and the coolant stayed in the tank. We didn’t have to replenish it very much, so even though initial cost was higher, replenishment cost was lower. Parts were shinier, tool life improved, and machining, especially of the forging dies, was faster.”

Within 2 months, the shop switched to the new fluid in all machines and saw multiple benefits. The work environment improved because the pervasive oil mist was eliminated. “The shop is much cleaner,” Cramer said. “The floors are not oily, and parts are easier to handle.”

The semisynthetic fluid also eliminated foul odors from microbial contamination in machine sumps, and machine downtime decreased because sumps no longer required cleaning every 3 to 4 weeks.

Coolant consumption also significantly decreased. “Basically, we have never changed coolant since we began using this fluid over a year ago,” Cramer said. “We don’t throw worn-out coolant away; we just replenish it as it becomes depleted.”