Metal Forming Operations

Rolling: makes sheet metal(hot or cold)

Forging: makes strong solid parts(hot or cold)

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Wire drawing: Makes strong small dia. wire(hot or cold)

Extrusion:makes complex cross-sections from soft metals and plastics(hot)

Kalpakjian

Kalpakjian

www.capalex.com

Bending: (2D)Bend sheet metal about single axis(hot or cold)

Deep drawing (3D)Makes “cups” from sheet metal,for mass production.(cold)

Kalpakjian

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Spinning:Makes “cups” from sheet metal,for lower production.(cold)

Roll forming (Hot):Moves bulk metal, makes I-beams

Kalpakjian

Kalpakjian

Kalpakjian

Roll forming (Cold):Bends sheetmetal into complex cross-sections

Shearing:Cut or punch sheetmetal(hot or cold)

Kalpakjian

ASM Metals Handbook Vol.9

Bralla

FormingOriented flowlines decrease fracture risk from grain boundaries, improve strength along flow direction.(Directional properties).Especially seen in:-Forging-Rolling-Drawing

Cracks tend to start where grain boundaries intersect surface. Forging minimizes these.

Thread-rolling for bolts: Rolled threads stronger than machined (and less expensive)

Kalpakjian

Directional Properties in RollingOriented flowlines:-Less ductility when bent in one direction-More ductility when bent in the other

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Slab Production: Hot Rolling

www.labware.com

www.falckacciai.it www.beautifuliron.com

Color & Temp

Progressive Hot Rolling: smaller, uniform grains

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Hot Working:Forging

Paul Berenson, www.paulb.comT.Green, WIT

www.smeedwerkunica.nl

Open Die Forging

Hydraulic press Mechanical press with an eccentric drive: fasterSlow but high forceand low cost

Forging Presses

Kalpakjian Erie Press

Forging Presses

Knuckle-joint press Screw press Gravity drop hammer:Simplest

Kalpakjian

Forging: Closed Die Forging

Kalpakjian

Forging: Heat LossMetal near die surfaces are coolest, flow less

www.lft.uni-

erlangen.de www.freedomalloysusa.com

Kalpakjian

Upset Forging (hot or cold)Bolt manufacture

Roll Forming (hot):

I-beams

Kalpakjian

Lunchtime on a Crossbeam, Unknown, www.buffalogames.com www.civil.ubc.ca

Extrusion (hot or cold):Typ.: Alum., soft metals

With special lubes: steels

~Any cross-section

Inexpensive dies

Good finish

T.Green, WIT en.wikipedia.org

Extrusion:

Hollow cross-sections: Use Mandrels

Kalpakjianwww.abra.net.au

Mannesmann Process: Piercing (Hot) Seamless pipe, tube

Kalpakjian

Cold-Working (vs. Hot):Products:• Better tolerances• Much better surface finish• Elongated (and smaller) grains• Turns inexpensive alloys into stronger but less ductile products• Sheetmetal lends itself to cold working, not hot working

Processes:• Higher processing forces• Larger and stronger machinery• Less ductility available• Lower energy use

Cold Rolling: Sheetmetal production

Kalpakjian

www.nzsteel.co.nz finance.pipex.com

Cold Rolling: Sheetmetal production

Cluster rolls support smaller contacting rolls

www.sendzimir.com

www.elgiloy.com

Cold Rolling: Sheetmetal production

Residual Stresses may lead to warping after bar is machined

Large reduction Small reduction

Kalpakjian

Roll Forming of Sheetmetal (cold)

Kalpakjian

www.cometroll.com www.safeair-dowco.com

Roll Forming of sheetmetal

www.mortonbuildings.com

Punching & Blanking of Sheetmetal

Punching (Scrap)

Blanking (Saved: a “blank”)

Punch

Die

Stripper plate

T.Green, WIT

Punching ofSheetmetal

Kalpakjian

Blanking of Sheetmetal: Efficient Nesting of Blanks

Kalpakjian

Sheetmetal: Bending

Kalpakjian

Springback:

Sheetmetal: Minimum Bend Radius

Kalpakjian

Tight radius bends (folds) require metal with ~40% ductility

Kalpakjian

Bending of SheetmetalUse notches to avoid tearing and wrinkling in right-angle bends

Press Brakes:For lower production

volumes

10-30 foot long

50-3000 tons

Bending of Sheetmetal

www.loomismetals.com

Bending:Press-Brake Operations

Kalpakjian

For large quantities, forging and die casting are more economical. Sand casting is the more economical process for fewer than about 20,000 pieces.

Relative Unit Costs of a Small Connecting Rod

Kalpakjian

Deep Drawing (cold, for sheetmetal)- Punch draws blank into die- Metal is supported on both sides to avoid wrinkling- Hold-down pressure (blankholder force) is primary process variable if too high: tearing if too low: wrinkling

Kalpakjian

www.endo-mfg.co.jp

Deep Drawing“Draw beads” may be used to control metal flow

Kalpakjian

www.dissco.co.nz

SpinningIdeal for • Lower production volumes• Large parts• Inexpensive tooling

www.traditional-building.com

www.ashfordmetalspinning.co.uk

Spinning videos

Cost comparison: manufacturing a round sheet-metal container by spinning and deep drawing. For small quantities, spinning is more economical.

Kalpakjian

Finite Element SimulationsPredict and minimize tearing and wrinkling locations

nsmwww.eng.ohio-state.edu

www.esi-group.com

tmku209.ctw.utwente.nl

Progressive Stamping DiesCommon method to handle complex parts

www.nissin-precision.com

Tube-drawingDOM: Drawn Over Mandrel Tubing

Seamless

Thin wall, tight tolerance, strong

Kalpakjian

www.twmetals.com

Malicky

“Floating plug”

Bicycles: Butted DOM tubingIncreased wall thickness at ends

Reinforces high stress points

materials.npl.co.uk

www.torelli.com

Diego Rivera, Detroit Industry, Detroit Institute of Art

References

Kalpakjian: http://www.nd.edu/~manufact/index3.htm

Bralla: James G. Bralla, Design for Manufacturing Handbook, McGraw-Hill, 2nd Edition. In: www.rose-hulman.edu/~stienstr