BOLT manufacturing process.pdf

Bolt Manufacture:

Process Selection

ver. 1

ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009

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How would you make a bolt?


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Questions you might ask in response:Questions you might ask in response:

• Make it out of what (material)?( )• Make how many (volume)?• Make it how well (quality, tolerance)?(q y, )• Make how fast (rate or time)?• Make it how cheaply (cost)?Make it how cheaply (cost)?• Make it how large (size, dimensions)?• Make it for what (function)?Make it for what (function)?


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Possible Manufacturing Methods gfor Metal Bolts

C ti• Casting• Powder processing• Rolling / Heading• MachiningMachining• Welding head to threads

R id t t i• Rapid prototyping


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CastingCasting• Sand • Die• Shell• Expendable mold

• Centrifugal• Squeeze

• Plaster• Ceramic

• Semi-solid• Single crystal

• Investment• Slush

g y• Directional

solidification• Pressure


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Sand CastingSand Casting

RisersSprue

Risers

GateCope

Parting Line

Gate

DragCasting

Parting Line


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Powder ProcessingPowder Processing

• Cold compaction and sinteringp g– Pressing– Rollingg– Extrusion– Injection moldingInjection molding– Isostatic pressing

• Hot Isostatic Pressing• Hot Isostatic Pressing


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Powder Pressing and Sinteringg g

PunchPunch

DieDie Part

Punch

Dual action press


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Cold Isostatic Pressing


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Hot Isostatic Pressing


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Rolling / HeadingRolling / Heading

• Roll the threads• Upset forge the headg


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Thread Rolling Machineg


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Thread Rolling Dieg


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Heading ProcessPunch

Blank

Kickout pin Die


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Forge for Headingg g


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MachiningCut threads on a lathe from hexagonal

stockstock


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Weld Head to ThreadsWeld Head to Threads• Threads :

ll d– rolled– machined

• Head:– cut from

barstock• Welding:

– arc– oxyacetylene


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y y

Rapid Prototyping - PowderRapid Prototyping Powder Processing

Direct fabrication from a CAD file

• Selective Laser Sintering (SLS)3 D P i ti• 3-D Printing

• Light Engineered Net Shaping (LENS)


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Layered Manufacturingy g

LaserMirrorMirror

LayeredObject

Vat

Platform


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Selective Laser Sintering g(3D Systems)


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3D Printing Process (Soligen)


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3D Printing Head (Soligen)3D Printing Head (Soligen)


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Light Engineered Net Shaping (1)(S di N ti l L b)(Sandia National Lab)


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Light Engineered Net Shaping (2)Light Engineered Net Shaping (2)(Sandia National Lab)

Laser

Powderdeliverytube


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Light Engineered Net Shaping PartsLight Engineered Net Shaping Parts(Sandia National Lab)


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Organize ProcessesOrganize Processes

• CastingCasting• Powder

Compaction– Compaction– Rapid Prototyping

D f ti• Deformation• Machining


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Material Properties LimitsMaterial Properties LimitsProcess Effect on thread strength

Casting Brittle, due to grainstructure

P d C b b ittl d tPowder Can be brittle due tosintering process (voids,incomplete fusion)

Deformation Good strength due to coldDeformation Good strength, due to coldworking and graindeformation

Machining Reduced due to sharpac g educed due to s a pcorners, and cuttingthrough grains


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Problems due to grain structureProblems due to grain structure• Cast objects have grains that j g

grow together.• Cast objects are not cold workedCast objects are not cold worked.

Th f f tTherefore, fracture can occur along grain boundaries more

ileasily.


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Si t i P blSintering Problems

Voids Incomplete fusion

vs.


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Grain Deformation vs CuttingGrain Deformation vs. Cutting(rolling vs. machining)

MachinedRolledRolled


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Mass ProductionMass ProductionProcess Mass Production

Casting Yes

Powder Yes for compaction;No for Rapid Prototyping

D f i YDeformation Yes

Machining Yesg


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CostCostProcess Cost

Casting Low

Powder Can be high; especiallyrapid prototyping

D f ti LDeformation Low

Machining Lowg


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FlexibilityFlexibilityProcess Flexibility

Casting Low

Powder High for RapidPrototyping

Deformation Low

Machining HighMachining High


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ToleranceToleranceProcess Tolerance

Casting Low

Powder Good

D f i G dDeformation Good

Machining Highg g


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Which process to pick?

• Normal sized bolts, mass d d d t thproduced, good strength:Rolling and heading

• Small bolts, mass produced:Machining on screw machineMachining on screw machine

• Large bolts, small numbers:M hi iMachining


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SummarySummary

• Choice depends on what you are trying• Choice depends on what you are trying to accomplish.Ch i i t i l t k• Choosing is not a simple task.

• Lots of thought and calculations are needed.


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