Presentation on theme: "Introduction to Cold Forming"— Presentation transcript:
1 Introduction to Cold Forming March 6, 2007Independence, OhioPresented byCarpenter Technology CorporationCopyright 2007 CRS Holdings, Inc.
2 Material Characteristics Applications Steps to Manufacture IntroductionTerminologyProcessesBenefitsMaterial CharacteristicsApplicationsSteps to ManufactureCoatings and LubricantsThe information and data presented herein are typical or average values and are not a guarantee of maximum or minimum values. Applications specifically suggested for material described herein are made solely for the purpose of illustration to enable the reader to make his/her own evaluation and are not intended as warranties, either express or implied, of fitness for these or other purposes.
3 History and Development of Cold FormingMarch 23, 1794Josiah Pierson – “Cold Header” Rivet MachineNovember 16, 1796Isaac Garretson – U.S. Patent for nail cutting & heading machine
4 Cold Forming Terminology Cold Forming terms:Cold Heading:cold forming process in which the force of the punch must exceed the material’s elastic limit to cause plastic flowelastic limit = yield strengthforging operation without the heat
5 Cold Forming Terminology Cold Forming terms:Cold Extrusiondecreasing the diameter of the blank by pushing it through a smaller holereduces size without yield lossCold Forming:generic term describing the combination of cold heading with cold extrusion
6 Cold forming machines - by the number of dies and blows Applications:Cold forming machines - by the number of dies and blowsfor example:1 Die/2 blow2 Die/3 blow2 Die/4 blow
7 The wire is fed in through the cut-off die to a wire stop. The cut-off knife shears the blank.
8 The cut-off knife transfers the blank to the heading die.
9 Now the blank is ready to receive the first punch operation. Proper cut-off of blank is critical.Blank mass equals mass of finished part.
10 Upsetting of a fastener head is accomplished by using one of these 4 methods.
11 Typical 1-Die/2-punch method is common in producing headed fasteners. The first blow combines coning with shank extrusion.Coning is a partial head upset.The second blow finishes the head shape.
12 Knockout pin acts as a blank support, during heading operation. Then ejects finished part.Rule of thumb:Unsupported pin not to exceed 8DSupported pin is recommended over 8D
13 Open ExtrusionTrap Extrusion30% area reduction75% area reduction
14 Examples using trap extrusion and open extrusion.
22 Benefits of Cold Forming Advantages of Cold FormingDesign VersatilityHigh strength parts from non-heat-treatable alloysMost cost effective way vs. milling, machining, hobbing and chemical etchingHigh production ratesMetallurgical EffectsGrain flowImproves strength, hardness, toughness & fatigue resistanceMaterial Savings
23 Benefits of Cold Forming Heading improves the finished part’s grain structure by making it conform to the flow of the design.The machined diagram shows how the grain structure is weakened by cutting operations.
26 Materials - Characteristics DescriptionTensile (ksi)YieldFormabilityCost IndexSteel = 1Aluminum AlloysTensile strength of mild steel with 1/3 the weight. Ex: 20245550Excellent5.0BrassAlloy of Cu & Zn. Tough, rustproof. Relatively inexpensive. Ex: 274 Yellow Brass60 min40 min6.0CopperHigh corrosion resistance. Expensive. Ex: 110 Electrolytic Tough Pitch35 – 4010 – 356.5Nickel AlloysApproximately 2/3 Nickel, 1/3 Cu with small amounts Fe. High strength, resistance to heat and corrosion.Ex: NiCu40080 min18.0
27 Materials - Characteristics Typical max Tensile as annealed DescriptionTypical max Tensile as annealedTypical max Tensile w/50% cold workFormabilityCost IndexSteel = 11010Low carbon5562Excellent110186598Good to Excellent1022Medium carbon70108103885157Fair to Good4037Medium carbon low alloy831661.5
28 Materials - Characteristics Typical max Tensile as annealed DescriptionTypical max Tensile as annealedTypical max Tensile w/5% cold workFormabilityCost IndexSteel = 1410Martensitic Stainless Steel7890Fair4.0430Ferritic Stainless Steel7586302HQAustenitic Stainless Steel834.530593A-28695Fair to Poor6.5Pyromet® 718Hi Temperature Alloy120135Poor12.0Pyromet is a reg. tm. of CRS Holdings, Inc.
30 Applications for Cold Formed Parts Automotivebrake partsball joints & steering partsstarter pinionsoxygen sensorsconstant velocity jointsmanifold boltsengine valvesAppliance Industrygearsfasteners for assembly
31 Applications for Cold Formed Parts Construction, Off-road equipmentbolts, nutsscrews – tapping, window, roofing, decktransmission gearssimilar parts for automotiveAerospacerivets, fuselageengine boltsfasteners - landing gear, interior
33 Decision Process for Cold Forming EquipmentMaterialPartwhich machinewhich toolsskill of personnelformabilityincoming conditionaccuracytolerancesadditional treatments
34 Decision Process for Cold Forming Production of Headed Parts Cold HeadingWarmHeadingHot HeadingRoom Temperature Forming of heated Forging temperaturesNo heat slugs at temperatures from 950 – 1250 °Cfrom: 550 – 950 °C (1740 – 2300 °F)(1020 – 1740 °F)
36 Decision Process for Cold Forming General Aspects of Heading MethodsForming TypeColdWarmHotTemperatureRoomoCoCoFoFaccuracyhighgoodlowformabilityrestrictedmateriallarge varietyenergy costsmoderatesurface qualitytolerancescloseclosergrain structurevariableheat treatmentsfewdefinitemachiningleastlessnecessary
40 Steps to Manufacture Raw Material Wire/Rod hot rolled shaved - ‘seam’ freecf/anlmaterial in the ‘softest’ conditionoptimum for cold forminganl/cfuniform volumeuniform diameterspecific incoming mechanical properties desired
41 Steps to Manufacture Heat Treatment of Raw Material Benefits Improves ability of deformationReduces hardnessImproves metal structure towards better forming
42 Steps to Manufacture Heat Treatment of Raw Material Types of heat treatmentTempering to form spherical cementiteAnnealingto remove strain hardeningto set the desired mechanical propertiesto normalize the microstructure
46 Steps to Manufacture Cold Forming Single stage presses Multi stage pressesup to 5 or 6 stages, as many as 8Secondary forming operationsthreadingrolledmachined
47 Steps to Manufacture Heat treatment after Cold Forming Annealing relieve stressre-crystallizenormalizeHardeningincrease the hardness after forming
48 Steps to Manufacture Metal Removing Hard Surfaces Soft Surfaces turninggrindinghoninglappingSoft Surfacesdrillingmilling
49 Steps to Manufacture Surface Treatment Cleaning of parts de-phosphatewashingacid to remove copper coatingCorrosion protectionpassivation – stainless steelPlatingzincchromate - Cr+6 (hexavalent chrome) can be a problem
50 Coatings and Lubricants Usesprevent metal to metal contact with tooling, gallingact as a carrier for machine lubricantsTypesprecoatlimecopper platingzinc phosphatemolybdenum disulfideoxalate
51 Coatings and Lubricants Typessoapscalcium stearatesodium stearatedrawing oilsMetal-removing coolantsoilemulsionsynthetics
53 Sources:“Heading Hints: A Guide to Cold Forming Specialty Alloys” - Carpenter Technology Corporation (2001)“Steel Wire Handbook Vol. 3” – The Wire Association, Inc.(1972)“Tool Design and Part Shape Development for Multi-die Cold Forming” - National Machinery Co.(1976)“Cold Forming 101” - Fastener Technology International (June 2005)
54 Thank you for your interest in cold forming of wire Thank you for your interest in cold forming of wire. More information about Carpenter is available on this website including technical datasheets and articles, Products and Markets. Visit Product Literature to request a free copy of “Heading Hints: A Guide to Cold Forming Specialty Alloys.” To contact Carpenter, call in the U.S. or refer to the Contact Us page for the location nearest you.