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Although a dictionary might define a spindle as a revolving piece, it does not say anything about one turning at 180,000 revolutions per minute (rpm). or having power output between 0.25 and 28 horsepower. Or lasting 3,000 to 10,000 hours. Those are, however, all attributes of the high-grade industrial spindles made by The Precise Corporation, a world leader in designing and manufacturing spindle systems.
A Precise electric spindle contains a dynamically balanced shaft that is driven by an integral motor and turns on pre-loaded, high-precision ball bearings. The spindle's accuracy enables the cutting tool to work at high speeds and produce excellent surface finish. Its light chip load, low tool pressure and low level of residual stress on the work piece result in very accurate parts.
Dick Garski, vice president of sales, describes how Precise products are installed and used. "A spindle is attached to a stationary machine or some type of robotic arm. The high frequency integral motor turns the spindle's shaft, which drives the cutting tool for high-speed milling, drilling or grinding applications." As an example, he adds, the Boeing Company uses Precise spindles to drill rivet holes in aircraft and Mikron Bostomatic incorporates them into the machines the company builds for cutting carbon graphite electrodes for the mold industry. Die Quip Corporation incorporates them into the grinding machines it builds for grinding draw dies used for sizing steel wire and copper tubing. Jostens uses spindle power to make the molds for school rings. Sea Ray shapes the Styrofoam molds used to build boats and Winnebago cuts the slots for wiring and stiffeners in the sidewall insulation of mobile homes.
Says Garski, Precise spindles are built with tolerances of 1 micron - an impressive standard, especially considering that the company manufactures well over a thousand spindles a year and has more than 60 type variations.
The development of Precise spindle systems - which includes the spindle, a high-frequency converter to power it, a cooling system to dissipate the heat generated from the spindle bearings and motor, and a bearing lubricator if the spindle does not have pre-greased bearings - reflects the Wisconsin company's evolution. Founded in Racine, Wis., in 1941 as Precise Products Corporation by the Schumann family, the company originally made hand grinders. In 1948, the first grinder-miller hand tool, with a 45,000-rpm speed range, was produced.
The first Precise spindle designed to be mounted rigidly in a machine tool was manufactured in 1951, the first with a high-frequency motor in 1960 and the first liquid-cooled spindles in 1970. Those three design advances remain integral to the products Precise manufactures today. Along the way, in 1968, Rockwell Manufacturing Company in Pittsburgh, Pa., acquired the business.
In 1974 Precise introduced automatic tool change to meet the needs of the printed circuit board industry. The following year the company became independent again when H.C. Stuckeman of Pittsburgh purchased it. Precise then became involved in early development of the HSK spindle taper system, which enables safe operation of automatic tool change spindle designs at progressively higher rational speeds. Another milestone was achieved in 1991 when Precise became the first to offer spindles with taper size HSK 25. Later technological advances included oil-air lubrication, ceramic bearings and air-bearing spindle designs for special applications. Still a privately owned enterprise, Precise was acquired in 1997, by David C. Easley, the son-in law of Stuckeman.
At the International Machine Technology Show (IMTS) in Chicago this fall Precise introduced its newest in a long line of innovations: the synchronous motor. The new SD 60122, SD 60124 and SD 5084 spindle designs incorporate specially designed permanent-magnet synchronous motors to produce constant torque through the entire speed range. Emphasizing the importance of this innovation, Garski says, "In the machine tool industry, there are many different types of applications. As far as customers wanting to use one spindle to do it all, now we're a big step closer to doing that."
Pivotal Capabilities and Facilities
The speed, power and tool interface achieved with Precise spindles help reduce machining time, minimize secondary operations and achieve precision tolerances - benefits that can increase productivity and profits. To help customers realize those benefits, Precise offers a program of services, including:
• technical consulting to help identify the right application solutions;
• test machining of the customer's material and cutters on their machine or on a machine at the Precise factory;
• worldwide application assistance, sales and service.
In addition to its 40,000-square-foot manufacturing facility in Wisconsin, where 45 people are employed, Precise has a comparable facility in Leichlingen, Germany. The U.S. business markets to customers in North and South America, Australia and New Zealand; the German plant serves Europe, Asia and Africa. The U.S. sales operation has three sales channels:
• independent manufacturers' representatives, distributors and an in-house team of sales experts and application engineers who work closely with all customers including original equipment manufacturers.
• Repair services and retrofitting are two more areas in which Precise offers customers proprietary capabilities. Garski explains that a spindle can last 3,000 hours or more, depending on how it is used, and adds, "Bearings will eventually wear out. How long a spindle will last depends on how it is used, whether the warm-up procedure is done every day, and whether the equipment is crashed into the machine's work table, work piece or if unbalanced tools are used causing high vibration. When a failure occurs, we can renew a spindle back to original engineering specifications."
Retrofitting - upgrading a machine with a faster spindle to increase productivity - is an important area of servicing customers. "Customers have been asking us for turnkey installation service, but it required special engineering. Now we have a partnership with Numatix/Pro Tech in Farmington Hills, Mich., to install our spindles into retrofit machines. This will be a growing market for us."
"Our company," Garski adds, "is going to continue to grow. Even as the machine tool market goes up and down, we will stay in it and make sure that we're in front of our customers helping them solve their application problems. We want to be their partner in precision."