Machining parts weighing up to 30 tons requires a massive machine tool, but many of those parts have complex features requiring contouring. About 70 to 90 percent of the machining performed on each part is milling and about 10 to 30 percent is contouring. On a large machine, such as a horizontal boring mill, contouring can be accomplished with an attachment-type contouring head. “The attachments work just fine but they require some amount of manual intervention,” said Peter Beyer, director of product strategy and product development for machine tool builder MAG IAS LLC.
Large U-axis machines are available for contouring, but that means having two machines and doing the milling on one machine, then transferring a heavy workpiece to the U-axis machine.
Production Machine & Tool is moving toward machining megaparts with complex features, such as bottle bores, phonographic sealing surfaces and external profiles, and didn’t want to pursue either of those scenarios. Instead, the parts manufacturer acquired a first-in-the-industry boring mill from MAG to perform that work on one machine without manual intervention, noted PMT President Mark McMullen.
MAG offers an optional integrated contouring head on its Giddings & Lewis horizontal boring mills.
The new machine, a Giddings & Lewis RT 1250U horizontal boring mill, has an integrated contouring head with a slide stroke to turn features up to 540mm (21.3 ") in diameter with standard Coromant Capto C8 tools and can accommodate workpieces weighing up to 60,000 lbs. Beyer explained that the machine’s main spindle motor drives the contouring spindle, which is mounted directly above the main spindle and engaged by a clutching mechanism. “There are no attachment-changing functions required,” Beyer said. “All the tool changing into the contouring spindle is automatic, so manual intervention is eliminated. You not only increase efficiency, but also improve part quality because motions and functions that can introduce errors are eliminated.”
Essentially, the new machine can do lathe work on a mill, McMullen said. “You get the workhorse of the standard boring mill and then you get the second spindle that does U-axis work.”
The contouring spindle has a Coromant Capto C8 interface and loads tools via the machine’s automatic toolchanger. In addition, a through-coolant contouring spindle (up to 300 psi, or 20 bar) clears chips and reduces tool wear. “My programmers now make me promise never to buy a mill without coolant through the spindle,” McMullen said.
To handle the large-part machining, PMT is adding about 25,000 sq. ft. to its facility and installing a crane with a 30-ton capacity. PMT expects delivery of the 125,000-lb. machine tool in the first quarter of next year. “It’s going to require a lot of concrete,” McMullen said about the machine’s foundation.
For more information about Production Machine & Tool, Wichita Falls, Texas, call (940) 767-940 or visit www.production-machine.com. For more information about MAG IAS LLC, Fond du Lac, Wis., call (920) 921-9400 or visit www.mag-ias.com. CTE
Related Glossary Terms
- automatic toolchanger
automatic toolchanger
Mechanism typically included in a machining center that, on the appropriate command, removes one cutting tool from the spindle nose and replaces it with another. The changer restores the used tool to the magazine and selects and withdraws the next desired tool from the storage magazine. The changer is controlled by a set of prerecorded/predetermined instructions associated with the part(s) to be produced.
- boring
boring
Enlarging a hole that already has been drilled or cored. Generally, it is an operation of truing the previously drilled hole with a single-point, lathe-type tool. Boring is essentially internal turning, in that usually a single-point cutting tool forms the internal shape. Some tools are available with two cutting edges to balance cutting forces.
- 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.
- gang cutting ( milling)
gang cutting ( milling)
Machining with several cutters mounted on a single arbor, generally for simultaneous cutting.
- lathe
lathe
Turning machine capable of sawing, milling, grinding, gear-cutting, drilling, reaming, boring, threading, facing, chamfering, grooving, knurling, spinning, parting, necking, taper-cutting, and cam- and eccentric-cutting, as well as step- and straight-turning. Comes in a variety of forms, ranging from manual to semiautomatic to fully automatic, with major types being engine lathes, turning and contouring lathes, turret lathes and numerical-control lathes. The engine lathe consists of a headstock and spindle, tailstock, bed, carriage (complete with apron) and cross slides. Features include gear- (speed) and feed-selector levers, toolpost, compound rest, lead screw and reversing lead screw, threading dial and rapid-traverse lever. Special lathe types include through-the-spindle, camshaft and crankshaft, brake drum and rotor, spinning and gun-barrel machines. Toolroom and bench lathes are used for precision work; the former for tool-and-die work and similar tasks, the latter for small workpieces (instruments, watches), normally without a power feed. Models are typically designated according to their “swing,” or the largest-diameter workpiece that can be rotated; bed length, or the distance between centers; and horsepower generated. See turning machine.
- 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 machine ( mill)
milling machine ( mill)
Runs endmills and arbor-mounted milling cutters. Features include a head with a spindle that drives the cutters; a column, knee and table that provide motion in the three Cartesian axes; and a base that supports the components and houses the cutting-fluid pump and reservoir. The work is mounted on the table and fed into the rotating cutter or endmill to accomplish the milling steps; vertical milling machines also feed endmills into the work by means of a spindle-mounted quill. Models range from small manual machines to big bed-type and duplex mills. All take one of three basic forms: vertical, horizontal or convertible horizontal/vertical. Vertical machines may be knee-type (the table is mounted on a knee that can be elevated) or bed-type (the table is securely supported and only moves horizontally). In general, horizontal machines are bigger and more powerful, while vertical machines are lighter but more versatile and easier to set up and operate.
- toolchanger
toolchanger
Carriage or drum attached to a machining center that holds tools until needed; when a tool is needed, the toolchanger inserts the tool into the machine spindle. See automatic toolchanger.
Author
Alan holds a bachelor’s degree in journalism from Southern Illinois University Carbondale. Including his 20 years at CTE, Alan has more than 30 years of trade journalism experience.
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