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Chapter 23Chapter 23

Machining Processes Used to Produce Round Shapes:Turning and Hole Making

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ProcessesProcesses

Turning (outside surface)

straight, taper, facing, contour, form, cut-off,

threading, knurling Boring (internal holes)

taper, form, drilling, threading, reaming

Drilling (internal)

Reaming (internal)

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Machining Surface RoughnessMachining Surface Roughness

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Drilling HolesDrilling Holes

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Drilling OperationsDrilling Operations

Various types of drills and drilling and reaming operations.

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Drilling VideoDrilling Video

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Drilling MachinesDrilling Machines

Figure 23.24 (a) Schematic illustration of the components of avertical drill press. (b) A radial

drilling machine. Source: (b) Courtesy of Willis Machinery and Tools.

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Various Types of DrillsVarious Types of Drills

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DrillsDrills

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ReamersReamers

Figure 23.26 (a) Terminology for a helical reamer.

(b) Inserted-blade adjustable reamer.

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General Capabilities of DrillingGeneral Capabilities of Drilling

Feed, f

Speed, V

Depth of cut, d

Diameter, D

RPM, N

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Speeds and Feeds in DrillingSpeeds and Feeds in Drilling

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Drilling Design ConsiderationsDrilling Design Considerations

Design for clamping

Flat surfaces preferred

Tolerances requirements

Machinability of materials

Allowance for tool

Depth of hole (walking)

Diameter of hole

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Boring Process CharacteristicsBoring Process Characteristics

Single point tool

Enlarges or straightens an existing hole Produces accurate holes (better

tolerances than drilling)

Able to produce large internal holes

Can be performed on a lathe, boring mill,

or jig bore machine tools

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BoringBoring

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Boring and Boring MillBoring and Boring Mill

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Boring Design ConsiderationsBoring Design Considerations

Through holes, not blind holes

Greater length to diameter more difficult

Avoid intermittent cuts

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Turning ProcessTurning Process

Creates cylindrical external or internal

shapes

Creates flat surfaces on part ends (faces)

Uses a single point tool

Wide variety of shapes

The machine tool is called a lathe

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Lathe CAD VideoLathe CAD Video

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Video Lathe/TurningVideo Lathe/Turning

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Lathe Cutting OperationsLathe Cutting Operations Turning: produces straight, conical, curved, or

grooved workpieces

Facing: produces flat surfaces at the end of the

part and perpendicular to its axis. Also used to

produce grooves.

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Lathe Cutting OperationsLathe Cutting Operations

Parting or Cutting Off: cuts a piece from the

end of a part

Threading: produces external or internal

threads

Knurling: produces a regularly shaped

roughness on cylindrical surfaces, as in making

knobs

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Lathe Cutting OperationsLathe Cutting Operations

Form tool: produces axisymmetric parts

Boring: enlarges a previous hole or to

produce circular internal grooves

Drilling: produces a hole

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Cutting Screw ThreadsCutting Screw Threads

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LatheLathe

Figure 23.2 General view of a typical lathe, showing various components.

Source: Courtesy of Heidenreich & Harbeck.

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NC Lathe and TurretNC Lathe and Turret

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Parts Made on LathesParts Made on Lathes

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Turning OperationTurning Operation

Figure 23.3 Schematic illustration of the basic turning operation, showing depth-of-

cut, d; feed, f; and spindle rotational speed, N in rev/min. Cutting speed is the surfacespeed of the workpiece at the tool tip.

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ToolTool

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Turning FormulasTurning Formulas

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Turning ParametersTurning Parameters

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Turning Feeds & SpeedsTurning Feeds & Speeds

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Feeds & Speeds for Tool MaterialsFeeds & Speeds for Tool Materials

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Cost ElementsCost Elements

Equipment

Tooling

Setup time

Load/unload time

Direct labor

Indirect labor

Cycle time, idle time

Overhead rate

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Safety FactorsSafety Factors

Rotating parts or tools

Hot, sharp chips

Eye and skin irritation from cutting

fluids

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Example from BookExample from Book

A 6-in long, 0.5 in diameter 304 stainless-

steel rod is being reduced in diameter to

0.48 in by turning on a lathe. The spindle

rotates at N=400 rpm , and the tool istraveling at an axial speed of 8 in/min.

Calculate, the cutting speed, material

removal rate, cutting time, and power.