Related Glossary Terms
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.
Condition of vibration involving the machine, workpiece and cutting tool. Once this condition arises, it is often self-sustaining until the problem is corrected. Chatter can be identified when lines or grooves appear at regular intervals in the workpiece. These lines or grooves are caused by the teeth of the cutter as they vibrate in and out of the workpiece and their spacing depends on the frequency of vibration.
Workholding device that affixes to a mill, lathe or drill-press spindle. It holds a tool or workpiece by one end, allowing it to be rotated. May also be fitted to the machine table to hold a workpiece. Two or more adjustable jaws actually hold the tool or part. May be actuated manually, pneumatically, hydraulically or electrically. See collet.
Space provided behind a tool’s land or relief to prevent rubbing and subsequent premature deterioration of the tool. See land; relief.
Flexible-sided device that secures a tool or workpiece. Similar in function to a chuck, but can accommodate only a narrow size range. Typically provides greater gripping force and precision than a chuck. See chuck.
- computer-aided manufacturing ( CAM)
computer-aided manufacturing ( CAM)
Use of computers to control machining and manufacturing processes.
Rate of change of position of the tool as a whole, relative to the workpiece while cutting.
- inner diameter ( ID)
inner diameter ( ID)
Dimension that defines the inside diameter of a cavity or hole. See OD, outer diameter.
Workholder for turning that fits inside hollow workpieces. Types available include expanding, pin and threaded.
- outer diameter ( OD)
outer diameter ( OD)
Dimension that defines the exterior diameter of a cylindrical or round part. See ID, inner diameter.
- steady rest
Supports long, thin or flexible work being turned on a lathe. Mounts on the bed’s ways and, unlike a follower rest, remains at the point where mounted. See follower rest.
Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.
Euro-style collets for U.S. market
HARDINGE GROUP, Elmira, N.Y., (www.hardinge.com) manufactures solid collets, master collets and pads, solid feed fingers and master feed fingers and pads for Euroturn, Gildemeister, INDEX and Schütte multispindle machines, with 24-hour shipping of standard fractional and whole metric sizes. Decimal metric sizes and products for other machine builders are available for 5- to 7-day delivery. Hardinge has a semifinished blank program for pickoff burring collets and special-shape collets.
According to Hardinge, shops should match the collet size (order hole) exactly to the workpiece or bar stock diameter. “If you use inch bar stock, you should use fractional collets—not metric,” said Rick Schonher, Hardinge workholding product manager. Few metric sizes have a direct fractional equivalent. Metric collets for metric bar stock, fractional collets for inch bar stock and decimal collets for decimal bar stock will provide the best results, according to Schonher.
If the shop is using a ¼” bar stock with a 6mm collet, it could experience push-back, chatter or poor concentricity because the collet is smaller than the bar stock.
“Most operators don’t realize the ramifications of such a small variance in diameter,” Schonher said. “If the collet order hole is larger than the workpiece or bar stock, the part may pivot at the line of contact at the face of the collet. If the collet order hole is smaller than the workpiece or bar stock, the edges of the slots will bite into the workpiece and may damage the bar. When the collet is the proper size for the workpiece or bar stock, there is a full bearing along the angle and the circumference of each segment of the collet where they mate with the spindle angle (seat).”
Tilting rotary table works with multiple workholders
KOMA PRECISION INC., East Windsor, Conn., (www.komaprecision.com) distributes Tsudakoma’s RTT-111, CA, a high-speed, drop-trunnion, tilting rotary table that can use multiple workholding systems. The table is now equipped to utilize more systems, including system 3R and Erowa chuck and pallet systems, Northfield’s 5C collet closer and 2-jaw and 3-jaw chucks, and Hirschmann’s chuck and pallet system. The RTT-111, CA can also be used with a standard faceplate. The rotary table, with its pallet system, allows for five-sided access to the part when 5-axis machining. Vises, chucks and clamps limit access to the part, thus decreasing process efficiency, according to the company. Because the table rotates on center, shorter tools and less spindle travel are required. The pallet system creates a lower profile than parts held with conventional workholding, thus increasing rigidity.
Miniature swing clamps provide high clamping forces
FIXTUREWORKS, Fraser, Mich., (www.fixtureworks.com) offers an expanded lineup of Imao One-Touch clamps that offer high clamping force and come in miniature sizes. They are available with clockwise and counterclockwise clamping actuation. New designs include swing clamps with rotational or cam handles, swing clamps with torque control and retractable clamps with cam or adjustable handles. Clamping forces for the miniature swing clamps with a rotating handle range from 247 to 787 lbs., forces for swing clamps with a cam handle are from 180 to 629 lbs., retractable clamps with a cam handle offer clamping forces from 150 to 247 lbs., and swing clamps with an adjustable handle offer 449 to 1,348 lbs. of clamping force. These workholders clamp straight down on the workpiece. The arm swings away to allow part loading/unloading. The adjustable handle allows for greater clamping stroke, force and tightening in limited space and can be moved to avoid interference. The clamps’ adjustable contact-screw position may be reversed, offering pinpoint pressure loads for heavy-duty roughing.
Vise can be manually or hydraulically actuated, uses different jaw packs
HAINBUCH AMERICA CORP., Mequon, Wis., (www.hainbuchamerica.com) offers the QUADROK vise, which can be manually or hydraulically actuated. The vise’s jaws rest on the clamping unit, which is available in two different styles. With four screws and a 90º turn of the clamping unit, the upper unit can be separated from the lower unit. Depending on the application, the operator can choose different jaw packs or set up the vise for ID or OD clamping. The lowest clamping base is 195mm when using the QUADROK 120 and 200 clamping units. The mandrel adaptation for ID clamping brings the base to 115mm, leaving five sides of a workpiece accessible, even on a large machining table, according to the company. Depending on the version, the clamping ranges from 0mm to 150mm for type 120 and 80mm to 250mm for type 200. Jaw pairs provide 31 kN of force while providing an actuation force of 97 Nm at the manual jaw and 50 bars for the hydraulic clamping unit, according to Hainbuch.
New steady rest for Haas turning centers
KITAGAWA-NORTHTECH INC., Schaumburg, Ill., (www.kitagawa.com) has a new custom steady rest for Haas ST-40 turning centers. The steady rest supports the extreme rigidity and heavy cutting capabilities of the large-capacity machines and allows clearance for clamping and turret operations, according to Kitagawa-Northtech. It can grip workpieces up to 12.20" long. The company packages the ST-40 steady rest as a complete kit, according to Stuart Fishman, business development manager, OEM machine tool divsion.