Related Glossary Terms
Shaft used for rotary support in machining applications. In grinding, the spindle for mounting the wheel; in milling and other cutting operations, the shaft for mounting the cutter.
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.
- 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.
- 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.
Removal of undesirable materials from “loaded” grinding wheels using a single- or multi-point diamond or other tool. The process also exposes unused, sharp abrasive points. See loading; truing.
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 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 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.
Using a diamond or other dressing tool to ensure that a grinding wheel is round and concentric and will not vibrate at required speeds. Weights also are used to balance the wheel. Also performed to impart a contour to the wheel’s face. See dressing.
It didn’t take long for executives at Myles Tool Co. Inc. to realize that if they wanted to make the most of their 2005 expansion plans, they needed to overhaul how they made thread mills.
|END USER:||Myles Tool Co. Inc.
|CHALLENGE:||Boost thread mill production.|
|SOLUTION:||Wheel truing and dressing machine.|
|SOLUTION PROVIDER:||Rush Machinery Inc.
Since its founding in 1977, the Sanborn, N.Y.-based toolmaker focused primarily on low-volume orders for solid- carbide special tools. Myles Tool’s 30 or so employees regularly produced modified endmills, profile step drills, porting tools and other customized HSS and carbide products for industries ranging from aerospace and automotive to defense and medical.
Then 5 years ago, the company decided to branch out and offer a standard product line. The added emphasis introduced new challenges. The success of a special order business centers in large part on the technological expertise of the machinist to make the tool properly. Mass producing a standard tool line, on the other hand, emphasizes cycle time. Time spent setting up machines and running jobs comes under close scrutiny.
“Cycle time is very competitive [in mass production],” said Jeremy Bout, Myles Tool’s grinding supervisor during the expansion. “We needed to make sure that the machines were running as fast they as they could, that the time spent dressing and preparing the wheel was not eating up production time.”
In particular, the manufacture of thread mills, which had become a big focus for the company, was also a drain on machine productivity. Myles Tool devoted four of its seven CNC grinders to the operation.
“The large scale production of thread mills really brought the issue to a head,” Bout said. “We needed a very specific form on the grinding wheel, and to dress that in the machine
to manufacture the thread mill was very time-consuming—about 2 hours,” he said. “And that’s not billable time.” Bout estimated that at a shop rate of $80 per hour, the nonbillable
time spent internally dressing wheels ran into the tens of thousands of dollars.
The remedy, Myles Tool decided, was a wheel truing and dressing machine that would permit quick, offline dressing of production equipment. The task for finding one fell to Bout, who had two nonnegotiable criteria. “I wanted to be able to dress a three-wheel pack without dismantling [it],” he said. “So I needed to be able to pivot the dressing wheel at a certain angle to move it in and out, and that axis needed to be on bearings, not on dovetails.”
He also learned from Myles Tool employees who had operated wheel truing equipment in previous jobs that dust and grit generated during dressing could easily get inside the machine’s slides and prematurely wear out the equipment. Accordingly, Bout’s criteria included protection against such a hazard. He checked out three units, among them the Model FC-250W truing and dressing machine from Rush Machinery Inc., Rushville, N.Y.
“He told us he wanted to do offline truing and needed to free up production time on his machines,” recalled Ted Hildebrant, sales manager for Rush Machinery. “Our FC-250W was a good match and competitively priced against other products he was looking at.” The machine’s features include the ability to true and dress flats, angles and radii on diamond and CBN single- and multiple-wheel packs.
The FC-250W offered the dressing capabilities Bout was searching for. “When you dress three wheels without having to take them off the arbor, they run perfectly true,” Bout said. “It was important that we did not have to take our wheel packs apart to dress them. A stable wheel pack translates into a smooth cut, which saves cycle time and increases output.”
He also noted that the FC-250W has a solid cast iron base for vibration dampening and that all operator electronic and computer controls were placed on one side of the machine to allow easy operation. The machine axes, he observed, had linear bearings and were fully enclosed to protect against dust and grit.
In July of 2006, a Rush Machinery FC-250W was installed and operating at Myles Tool. “We’ve easily saved many [production] hours every week,” Bout said. “And those are billable hours that we have reclaimed.”