Chapter4 - MILLING PROCESS

FIG. 1 Typical parts and shapes produced by various cutting processes

Fig. 2 Schematic illustration of milling machines

Fig. 3 Milling machines

Fig 4 Nomenclature of a common milling cutter

Left hand spiral right hand spiral Left hand cutter right hand cutter Fig. 5 Left and right hand cutters. Helical Plain Fig. 6 Milling Cutters. a ) Helical b ) Plain

Fig. 7 Various types of milling cutters Slab mill Course tooth mill Helical mill Staggered tooth mill Side mill Interloching mill Metal slitting saw Fig. 7 Various types of milling cutters Helical mill (arbor type)

Fig. 8 Various types of end mills Woodruff Keyslot end mill Double-end end mill Two-lip end mill Shell end mill T-slot end mill

Fig. 9 Angle, concave, convex, corner and gear cutters Corner rounding cutter Covex formed cutter Gear tooth cutter Single angle cutter Double angle cutter Concave formed cutter

Fig. 10 Effect of milling cutter diameter on workpiece travel Large diameter cutter Amount of travel using large diameter cutter Direction of cut Material being removed workpiece Small diameter Amount of travel using small diameter cutter

Intermediate arbor support Fig.11 Tapers used for Milling machine arborrs Fig. 12The standard milling machine arbor Arbor Intermediate arbor support Arbor support Spindle Draw in bolt Milling cutter Journal bearing Arbor nut Fig. 13 Arbor installation

Fig. 14 Typical milling arbors

Milling machine adapters Chuck adapter Fig. 16 Adapters Fig. 15 Typical Collet types Fig. 17 Quick change adapter and tool holder.

Standard machine table vise Fig. 18 examples of various vises swivel vise Standard machine table vise The universal vise Fig. 19 The index head and footstock

Fig.22 Various mounting tools Fig. 20 Rotary table Fig. 21 Offset boring head Angle plate V-Block and clamp V-clamp C- clamp Step block Bent tail machine clamp Finger machine clamp Strap clamp C- clamp Fig.22 Various mounting tools

Fig. 24 correct mounting of workpiece in a vise Not correct Correct Workpiece Parallel Selection of Parallels Vise Centering of workpiece in vise Locating the workpiece at end of vise Fig. 24 correct mounting of workpiece in a vise Strap block Fig. 23 locating keys or tongues on the underside of the vise bases should be located correctly in relation to the T-slots on the milling machine table vise.

Brown and Sharpe type Plate I - 15, 16, 17, 18, 19, 20 holes Fig. 25 using hold down straps Fig. 26 The indexing plate Brown and Sharpe type Plate I - 15, 16, 17, 18, 19, 20 holes Plate 2 - 21, 23, 27, 29, 31, 33 holes Plate 3 - 37, 39, 41, 43, 47, 49 holes Cincinnati type First side - 24, 25, 28, 30, 34, 37, 38, 39, 41, 42, 43 holes Second side - 46, 47, 49, 51, 53, 54, 57, 58, 59, 62, 66 holes

Fig. 27 Examples of Milling Cutters and Operations a) Slab milling b) Face milling c) End milling Arbor Cutter Spindle Shank End mill Fig. 27 Examples of Milling Cutters and Operations d) e)

Fig. 28 Face-milling operation showing (a) action of an insert in face milling; (b) climb milling; (c) conventional milling; (d) dimensions in face milling. The width of cut, w, is not necessarily the same as the cutter radius.

f v (a) (b) Fig. 29 (a) Slab milling operation, showing depth of cut, d, feed per tooth, f, chip depth of cut, tc, and workpiece speed, v. (b) Schematic illustration of cutter travel distance lc to reach full depth of cut.

TABLE 1 Typical capacities and maximum workpiece dimensions for milling machines Machine tool Maximum dimension m (ft) Power (kW) Maximum speed Milling machines (table travel) Knee-and-column 1.4 (4.6) 20 4000 rpm Bed 4.3 (14) Numerical control 5 (16.5) Note: Larger capacities are available for special applications.

TABLE 1 Parameters and formulae of the milling process = Rotational speed of the milling cutter, rpm f Feed, mm/tooth or in./tooth D Cutter diameter, mm or in. n Number of teeth on cutter v Linear speed of the workpiece or feed rate, mm/min or in./min V Surface speed of cutter, m/min or ft/min =D N Feed per tooth, mm/tooth or in/tooth =v /N n l Length of cut, mm or in. t Cutting time, s or min =( l+lc ) v , where lc =extent of the cutter’s first contact with workpiece MRR mm3/min or in.3/min =w d v , where w is the width of cut Torque N-m or lb-ft ( Fc ) (D/2) Power kW or hp (Torque) ( ), where  = 2 N radians/min TABLE 1 Parameters and formulae of the milling process Note: The units given are those that are commonly used; however, appropriate units must be used in the formulas.

Fig. 31 A typical setup for plain milling Fig. 33 Straddel milling of a hexagon Fig. 32 is a typical example of angular milling. Fig. 34 Face milling

Fig. 35 Face milling of angular surfaces Fig. 37 Form milling Fig. 36 Gange milling.

Fig. 38 Fly cutting tools Key is milled to required length Cutter centered over the shaft Fig. 40 Milling rounded end key slot waysKey is milled to required length Fig. 39 The Woodruff key slot milling cutter

Fig. 41 T-slot milling cutter Fig. 43 The splines are cut by straddle milling Fig. 42 Parting of a solid stock