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Chapter 24Chapter 24

Machining processes that producevarious shapes: Milling, Broaching,

Sawing, and Filing; Gear Manufacturing

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Various Shaped PartsVarious Shaped Parts

Figure 24.1 Typical parts and shapes that can be produced with themachining processes described in this chapter.

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Milling CharacteristicsMilling Characteristics

z Milling machine tools

z Wide variety of rotating cutters to

produce chips (slab, face, end milling)

z Tool may be vertical or horizontal

z Produces flats, slots, angles, pockets,

radii, and many other geometries

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VideoVideo

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Milling MachinesMilling Machines

Figure 24.15 Schematic illustration of (a) a horizontal-spindle column-and-knee type milling machine and (b) vertical-spindle column-and-knee typemilling machine. Source: After G. Boothroyd.

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CNC Milling MachineCNC Milling Machine

Figure 24.17 A computer numerical-control (CNC) vertical-spindle milling machine. This machine is one of the most versatile machine tools. The original vertical-spindle milling machine iused in job shops is still referred to as a “Bridgeport”, afterits manufacturer in Bridgeport, Connecticut. Source: Courtesy of BridgeportMachines Dibision, Textron Inc.

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Slab, Face, and End MillingSlab, Face, and End Milling

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Face MillingFace Milling

z Produces flat surfaces quickly

z

Can produce stepped surfaces

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Face-Milling CutterFace-Milling Cutter

Figure 24.7 Terminology for a face-milling cutter.

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Face-milling Cutter (inserts)Face-milling Cutter (inserts)

Figure 24.5 A face-milling cutter with indexable inserts. Source:Courtesy of Ingersoll Cutting Tool Company.

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Face-Milling OperationFace-Milling Operation

Figure 24.4 Face-milling operation showing (a) action of an insert in facemilling; (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.

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Cutter Position in Face MillingCutter Position in Face Milling

Figure 24.9 (a) Relative position of the cutter and insert as it first engages theworkpiece in face milling. (b) Insert positions towards the end of cut. (c) Examples of exit angles of insert, showing desirable (positive or negative angle) and undesirable(zero angle) positions. In all figures, the cutter spindle is perpendicular to the page androtates clockwise.

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Slab MillingSlab Milling

Figure 24.3 (a) Schematic illustration of conventional milling and climb milling. (b) lab-milling operation showing depth-of-cut, d; feed per tooth, f ; chip depth-of-cut, tc; andworkpiece speed, v. (c) Schematic illustration of cutter travel distance, lc, to reach fulldepth-of-cut.

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Slab MillingSlab Milling

z Produces flat surfaces, contoured, or

shaped surfaces (grooves, gears, etc.)

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Slab Milling CuttersSlab Milling Cutters

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Slab Milling Process SettingsSlab Milling Process Settings

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End Milling CuttersEnd Milling Cutters

z Produces a wide variety of shapes

z Produces slots, angles, pockets, radii, and

many other geometries

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End Milling GeometriesEnd Milling Geometries

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End Milling CuttersEnd Milling Cutters

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End Milling Process SettingsEnd Milling Process Settings

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Milling EquationsMilling Equations

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Equations, 1Equations, 1

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Equations, 2Equations, 2

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Equations, 3Equations, 3

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Equations, 4Equations, 4

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Equations, 5Equations, 5

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Equations, 6Equations, 6

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Equations, 7Equations, 7

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Equations, 8Equations, 8

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Milling Machined SurfaceMilling Machined Surface

Figure 24.13 Machined surface features in face milling. See also Fig. 24.6.

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Insert Shape and Feed MarksInsert Shape and Feed Marks

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Milling Machine SettingsMilling Machine Settings

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Example 24.1 (from textbook)Example 24.1 (from textbook)

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Cost ElementsCost Elements

z Machine tool

z Setup time

z Load/unload time

z Cutting time

z Tool costs

z Direct labor cost

z Overhead

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Safety FactorsSafety Factors

z Rotating tool

z Hot and sharp chips

z Eye and skin irritation from cutting

fluids