456 Modern Metalworking Copyright Goodheart-Willcox Co., Inc. Problem: Determine the proper speed and feed for a 6″ diameter side cutter (HSS) with 16 teeth, ″ milling aluminum. Information available: Recommended cutting speed for aluminum (midpoint on range) ................. 750 fpm Recommended feed per tooth (midpoint on range) .......................................... .015″ Cutter diameter ....................................................... 6″ Number of teeth on cutter .....................................16 To determine speed setting (cutter rpm) the following is given in Figure 26-31: Rule: Divide the feet per minute (fpm) by the circumference of the cutter, expressed in feet. Formula: rpm = fpm × 12 πD = 750 × 12 = 9000 3.14 × 6 18.84 = 1500 = 478* 3.14 To determine feed setting (feed in inches per minute = F) Rule: Multiply feed per tooth per revolution by number of teeth on cutter and by speed (rpm). Formula: F = ftr × T × rpm = .015 × 16 × 478 = 115* *The speeds and feeds are approximate. Set machine to closest setting. 26.6 Workholding Attachments One of the more important milling machine features is its adaptabilityto large numbers of workholdingattachments. This in turn increases the usefulness of the machine. 26.6.1 Vises The vise is probably the most widely used method of holding work for milling. The jaws are hardened and ground for accuracy and wear. It is keyed to the mill- ing table with lugs, Figure 26-32. A flanged vise, Figure 26-33A, has slotted flanges for fastening the vise to the worktable. The slots permit the vise to be mounted parallel or at right angles to the spindle. The body of a swivel vise, Figure 26-33B, is Goodheart-Willcox Publisher Figure 26-32. Lugs on the base of a workholding attachment position the device on the worktable. Lug (2) fits into table slot Base of vise A A B Jergens, Inc. Photo courtesy of Grizzly Industrial, Inc. www.grizzly.com Figure 26-33. A—Typical flanged vise. B—The base on a swivel vise is graduated in degrees for rapid positioning.