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END USER: ZPS-Frézovací Nástroje a.s., +420-576-777-510, www.zps-fn.com. CHALLENGE: Increase capacity when producing milling cutters. SOLUTION: A two-spindle, automated, high-speed grinder. SOLUTION PROVIDER: Erwin Junker Machinery Inc., (847) 488-0406, www.junker-usa.com
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ZPS-Frézovací Nástroje a.s., a manufacturer of HSS milling tools, was looking to boost its market share and better equip a new training and education center at its headquarters in Zlín, Czech Republic. The center allows the company’s employees, as well as experts and students from technical-vocational schools and technical universities, to become acquainted with new manufacturing technology.
The company accomplished both goals with the installation of a new high-speed grinding machine, Lean Selection speed, from Erwin Junker Maschinenfabrik GmbH, Nordrach, Germany. Equipped with two grinding spindles and employing CBN or diamond grinding wheels, the machine combines fast grinding times and an automated loading system. ZPS uses the grinder for production runs and training demonstrations.
Courtesy of Junker
The Lean Selection speed machine grinds cylindrical, stepped and tapered ODs, as well as the cutting edge, in a single clamping.
The new machine replaced several conventional cylindrical grinding machines at ZPS, providing a higher rate of machine availability, higher part quality and higher output, according to the company.
Founded in the 1930s, ZPS has been manufacturing HSS milling cutters since the 1950s. Today, the company is the largest milling cutter manufacturer in the Czech Republic and employs about 120 people. In 2011, the company exported approximately 70 percent of its tools, with half going to Germany.
Courtesy of Junker
An automation system for the Lean Selection speed machine includes Junker’s Jurogot loading cell.
In recent years, ZPS has increased its export volume but its capacity for rough and finish grinding of milling cutters was limited. The new Junker machine, which supplies all the machines that follow it in the production line, provides the company with the capacity it needs. In 2012, ZPS estimates it will produce more than 300,000 milling cutters on the Lean Selection speed grinder and additional capacity is available on the machine if needed.
The Lean Selection speed grinding machine is equipped with a high-resolution B-axis. Each of the two 12,000- rpm grinding spindles has 12kVA drive power. The machine also features a glass scale on the X-axis, a Fanuc 0i control, Junker’s Juwop programming system and a tailstock with microfine adjustment.
With peripheral speeds of up to 140 m/sec., rough and finish grinding can be performed efficiently at high metal-removal rates using the Junker Quickpoint grinding method, according to Junker. With the Quickpoint method, the grinding wheel creates the final dimension on the outer contour of the milling cutter and removes the entire grinding allowance in one longitudinal pass. Grinding between male or female centers results in high accuracy, Junker reports. In addition to tool grinding, the machine can grind parts such as gearbox components and camshafts.
At ZPS, an automation system for the Lean Selection speed machine includes Junker’s Jurogot automated loading cell. A robot loads the parts through an opening in the machine hood. The machine grinds cylindrical, stepped and tapered ODs, as well as the cutting edge, in one clamping. In addition, a diameter gage on the grinding table provides automatic dimension correction.
ZPS is particularly pleased with the machine’s uptime. With batch sizes of 50 to 2,000 tools, ZPS’ Lean Selection speed requires two changeovers per day, on average. A three-point mounting interface on the grinding spindle and workpiece spindle simplifies this task.
ZPS is reportedly pleased with the start-up process, grinding quality and on-site customer service.
Related Glossary Terms
- centers
centers
Cone-shaped pins that support a workpiece by one or two ends during machining. The centers fit into holes drilled in the workpiece ends. Centers that turn with the workpiece are called “live” centers; those that do not are called “dead” centers.
- cubic boron nitride ( CBN)
cubic boron nitride ( CBN)
Crystal manufactured from boron nitride under high pressure and temperature. Used to cut hard-to-machine ferrous and nickel-base materials up to 70 HRC. Second hardest material after diamond. See superabrasive tools.
- cylindrical grinding
cylindrical grinding
Grinding operation in which the workpiece is rotated around a fixed axis while the grinding wheel is fed into the outside surface in controlled relation to the axis of rotation. The workpiece is usually cylindrical, but it may be tapered or curvilinear in profile. See centerless grinding; grinding.
- gang cutting ( milling)
gang cutting ( milling)
Machining with several cutters mounted on a single arbor, generally for simultaneous cutting.
- grinding
grinding
Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.
- grinding machine
grinding machine
Powers a grinding wheel or other abrasive tool for the purpose of removing metal and finishing workpieces to close tolerances. Provides smooth, square, parallel and accurate workpiece surfaces. When ultrasmooth surfaces and finishes on the order of microns are required, lapping and honing machines (precision grinders that run abrasives with extremely fine, uniform grits) are used. In its “finishing” role, the grinder is perhaps the most widely used machine tool. Various styles are available: bench and pedestal grinders for sharpening lathe bits and drills; surface grinders for producing square, parallel, smooth and accurate parts; cylindrical and centerless grinders; center-hole grinders; form grinders; facemill and endmill grinders; gear-cutting grinders; jig grinders; abrasive belt (backstand, swing-frame, belt-roll) grinders; tool and cutter grinders for sharpening and resharpening cutting tools; carbide grinders; hand-held die grinders; and abrasive cutoff saws.
- grinding wheel
grinding wheel
Wheel formed from abrasive material mixed in a suitable matrix. Takes a variety of shapes but falls into two basic categories: one that cuts on its periphery, as in reciprocating grinding, and one that cuts on its side or face, as in tool and cutter grinding.
- high-speed steels ( HSS)
high-speed steels ( HSS)
Available in two major types: tungsten high-speed steels (designated by letter T having tungsten as the principal alloying element) and molybdenum high-speed steels (designated by letter M having molybdenum as the principal alloying element). The type T high-speed steels containing cobalt have higher wear resistance and greater red (hot) hardness, withstanding cutting temperature up to 1,100º F (590º C). The type T steels are used to fabricate metalcutting tools (milling cutters, drills, reamers and taps), woodworking tools, various types of punches and dies, ball and roller bearings. The type M steels are used for cutting tools and various types of dies.
- milling
milling
Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.
- milling cutter
milling cutter
Loosely, any milling tool. Horizontal cutters take the form of plain milling cutters, plain spiral-tooth cutters, helical cutters, side-milling cutters, staggered-tooth side-milling cutters, facemilling cutters, angular cutters, double-angle cutters, convex and concave form-milling cutters, straddle-sprocket cutters, spur-gear cutters, corner-rounding cutters and slitting saws. Vertical cutters use shank-mounted cutting tools, including endmills, T-slot cutters, Woodruff keyseat cutters and dovetail cutters; these may also be used on horizontal mills. See milling.
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