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Page 1

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Machining ProcessesMachining Processes

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Machining ProcessesMachining Processes

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Machining ProcessesMachining Processes

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Fundamentals of MachiningFundamentals of Machining

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Fundamentals of MachiningFundamentals of Machining

z Machining is a general term describing a

group of processes that consist of the

removal of material an modification of

the surfaces of a workpiece after it hasbeen produced.

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Advantages and DisadvantagesAdvantages and Disadvantages

z Advantages

Good dimensional accuracy

Good geometry, sharp edges

Economical

z Disadvantages

Wasted material

More time than some other processes

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Page 2

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Elements of MachiningElements of Machining

z Machine (machine tool)

z

Materialz Cutting tool

z Operational plan and settings

feeds, speeds, etc.

z Environment (coolant)

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Examples of MachiningExamples of Machining

Figure 21.1 Some examples of common machining operations.

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Machine Tools: LatheMachine Tools: Lathe

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Milling Machine ToolsMilling Machine Tools

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Cutting Material with ToolCutting Material with Tool

Schematic illustration of the turning operation showing various features.

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TurningTurning

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Page 3

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Chip Making VideoChip Making Video

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Chips FormationChips Formation

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Chip Examples In ClassChip Examples In Class

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Cutting ToolsCutting Tools

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Tool TypesTool Types

z Tool steels

z High-speed steel

z Ceramics (aluminum oxide)

z Coated carbides

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Some Properties of Tool MaterialsSome Properties of Tool Materials

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Page 4

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Characteristics of Tool MaterialsCharacteristics of Tool Materials

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Relative Cutting Time

of Tool Materials

Relative Cutting Time

of Tool Materials

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Select Proper Tool VideoSelect Proper Tool Video

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Wear Patterns on ToolsWear Patterns on Tools

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Machined Steel SurfacesMachined Steel Surfaces

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Applying Cutting FluidsApplying Cutting Fluids

Figure 22.12 Schematic illustration of the proper methods of applyingcutting fluids (flooding) in various machining operations: (a) turning, (b)milling, (c) thread grinding, and (d) drilling.

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Page 5

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Turned Surface Feed MarksTurned Surface Feed Marks

Figure 21.23 Schematic illustration of feedmarks on a surface being turned (exaggerated).

Ra =

f2

8R

where

f= feed

R = tool - nose radius

Surface roughness:

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TerminologyTerminology

z Independent Variables

Material

(machinability) Cutting tool

Speed (sfpm)

Depth of cut (in)

Feed (ipr or ips)

Cutting conditions

z Dependant Variables

Metal removal rate

Cut time

Horsepower

Temperature

Surface finish

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Feed and Speed SelectionFeed and Speed Selection

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Factors Influencing MachiningFactors Influencing Machining

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Energy RequirementsEnergy Requirements

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Tool Life EconomicsTool Life Economics

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Page 6

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Tool LifeTool Life

z Taylors tool life model

z

Fredrick Taylor 1907 (ASME)z VTn = C (.08