Machine Tools MILLING PROCESS BY LAKSHMIPATHI YERRA Asst.professor Dept.of Mechanical Engg.
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 cutter right hand cutter Left hand spiral right hand spiral Fig. 5 Left and right hand cutters. Helical Plain Fig. 6 Milling Cutters. a ) Helical b ) Plain
Slab mill Helical mill Course tooth mill Helical mill (arbor type) Staggered tooth mill Side mill Interloching mill Metal slitting saw Fig. 7 Various types of milling cutters
Two-lip end mill T-slot end mill Shell end mill Double-end end mill Woodruff Keyslot end mill Fig. 8 Various types of end mills
Corner rounding cutter Covex formed cutter Gear tooth cutter Single angle cutter Double angle cutter Concave formed cutter Fig. 9 Angle, concave, convex, corner and gear cutters
Amount of travel using large diameter cutter Large diameter cutter Amount of travel using small diameter cutter Direction of cut Material being removed Small diameter cutter workpiece Fig. 10 Effect of milling cutter diameter on workpiece travel
Fig. 12The standard milling machine arbor Spindle Arbor Intermediate arbor support Arbor support Fig.11 Tapers used for Milling machine arborrs Draw in bolt Milling cutter Journal bearing Arbor nut Fig. 13 Arbor installation
Fig. 14 Typical milling arbors
Fig. 15 Typical Collet types Milling machine adapters Fig. 16 Adapters Chuck adapter Fig. 17 Quick change adapter and tool holder.
Standard machine table vise swivel vise Fig. 18 examples of various vises The universal vise Fig. 19 The index head and footstock
Fig. 21 Offset boring head Fig. 20 Rotary table 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. 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. Not correct Workpiece Vise Correct Workpiece Parallel Selection of Parallels Vise Parallel Workpiece Workpiece Centering of workpiece in vise Vise Workpiece Locating the workpiece at end of vise Strap block Fig. 24 correct mounting of workpiece in a vise
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
a) Slab milling b) Face milling c) End milling Cutter Arbor Spindle Spindle End mill Shank Arbor d) e) Fig. 27 Examples of Milling Cutters and Operations
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.
(a) (b) v f v Fig. 29 (a) Slab milling operation, showing depth of cut, d, feed per tooth, f, chip depth of cut, t c, and workpiece speed, v. (b) Schematic illustration of cutter travel distance l c to reach full depth of cut.
TABLE 1 Typical capacities and maximum workpiece dimensions for milling machines Machine tool Milling machines (table travel) Knee-andcolumn Maximum dimension m (ft) Bed 4.3 (14) Numerical control Power (kw) Maxi mum speed 1.4 (4.6) 20 4000 rpm 5 (16.5) Note: Larger capacities are available for special applications.
N = 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 MRR = Torque = Power = =D N f = 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+l c ) v, where l c =extent of the cutter s first contact with workpiece mm 3 /min or in. 3 /min =w d v, where w is the width of cut N-m or lb-ft ( F c ) (D/2) 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. 36 Gange milling. Fig. 37 Form milling
Cutter centered over the shaft Fig. 38 Fly cutting tools Key is milled to required length Fig. 39 The Woodruff key slot milling cutter Fig. 40 Milling rounded end key slot wayskey is milled to required length
Fig. 41 T-slot milling cutter Fig. 42 Parting of a solid stock Fig. 43 The splines are cut by straddle milling