chapter 2 machining

8/20/2019 Chapter 2 Machining

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Machining

Precise material removal to bring a part to specified size

• Automotive machining examples

Boring cylinders

Honing cylindersGrinding cranks and cams

Grinding or milling heads and blocks

Grinding flywheels

Copyright !!" Gary #ewis $ %ave Capitolo

%rilling and reaming for valve guides


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Machining

%rilling

• &nd cutting

• 'sed for roughing holes to si(e

• )eamers finish holes to si(e and surface finish


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Machining

*urning + boring

• *urning $ outside diameter with single pointed tools

on a lathe

• Boring $ inside diameter with single pointed tools on a lathe


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Machining

Milling

• ,ertical spindle

• 'sed to remove material

from a flat surface


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Machining

Milling

• *ypical milling cutters

H-- + carbide


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Machining

Grinding

• Abrasive machining using millions abrasive grains

• Minimal stock removal

• High surface finish .uality

,ertical spindle surfacing

• 'sed to grind flywheels/ blocks/ and cylinder heads


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Machining

Hori(ontal spindle grinders• 'sed for valve grinders/ crankshaft grinders/

and camshaft grinders


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Machining

Broaching• Chip removal is done with progressively larger

cutting teeth

• 0eyways in sprockets and gears

• 1ot done in auto machine shops


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Machining

*ool materials

H-- 2High speed steel3

• %rills/ reamers/ and milling cutters

• *ungsten/ vanadium/ and cobalt added for hardness

*ungsten carbide

• Boring bars and cutter of a face mill

• Attached to a tool holder• Heat resistant and operate at high speeds

2up to " times H--3

• Cobalt increased for shock resistance


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Machining

*ool materials

*ungsten Carbide 2cont43• As cobalt 5 increases/ resistance to shock increases/

resistance to heat decreasesAluminum 6xide grinding wheel

• 'sed for steel + nodular iron 2cranks + cams3

-ilicon Carbide grinding wheel

• 'sed for iron 2heads + blocks3


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Machining

#athe tool


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Machining

• )ake angles form the surface that the chips pass over • Back rake angle angles are greater for boring


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Machining

• )elief angles prevent the cutting tool from bumping into the work


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Machining

• 1ose radius affects surface finish• #arge radius increases power re.uired

and tool chatter


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Machining

-ide cutting angle• *he greater the angle/ the more tool deflection

• *he smaller the angle/ the bigger the chip and

more the tool will wear


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Machining

Cutting oils• &xtend tool life

• Cool cutting tool

• Cast iron can be machined without cutting oil

• Aluminum re.uires cutting oil

• All threading operations re.uire cutting oil


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Machining

-pindle tilt• *he spindles of automotive surfacing machines

are tilted about 4!!9:

• *his produces a 7hollow cut8 of less than 4!!!;:


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Machining

Conventional vs4 climb milling

• Conventional $ Cutter rotates

opposite direction of feed

• Climb $ Cutter rotates same

direction as feed


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Machining

%rill bits 2cont43• Morse taper 2;!?3/ for pilots and machining centers


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Machining

Core drills and countersinks• Core drills enlarge holes only/ will not cut in center

• Countersinks chamfer bolt holes 2=?3


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Machining

Counter bores• -potfacing head bolt holes


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Machining

Grinding• %iamond dresser 2trues wheels3

• -tar wheel dresser 2does not true wheel3


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Machining

Hard grinding action• 1o wheel breakdown

• #ittle material removal

• Burnt work

• heel needs dressing

-oft grinding action

• *oo much wheel breakdown• -tone material gets caught between wheel and work

• )ough surface finish


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Machining

Honing• -lower speed than grinding

• Honing stones must also break down

• Honing oils cool the work and flush

away the grit

chapter 2 machining

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