Forging of Metals

Forging of Metals

Introduction A metal is shaped by compressive forcesOldest metal working process 4000BCCan be performed with a hammer and anvilTypical forged products:BoltsRivetsConnecting rodsGears

Lading-gear components for the C5A and C5B transport aircraft, made by forging.Steps involved in forging a bevel gear with a shaft.

Outline of Forging and Related Operations

Grain Structure Parts have good strengthHigh toughnessForgings require additional heat treatingFig : A part made by three different procedures, showing grain flow (a) casting (b) machining (c) forging

Open-Die ForgingIs the simplest forging processSizes can very from very small parts to very large parts

Open-Die ForgingUpsetting or flat-die forging a solid workpiece is placed between flat dies and is compressed

Barreling caused by frictional forces at the die-workpiece interfacesCan be minimized if a lubricant is usedThermal effects caused by barreling can be minimized by using heated dies

Open-Die ForgingForging force

Impression-Die & Closed-Die ForgingThe workpiece acquires the shape of the die cavities while being forged between the two shaped dies

Impression-Die & Closed-Die ForgingThe blank to be forged is prepared by: Cutting from a bar stockPreformed blankCastingPreformed blank from prior forging

Impression-Die & Closed-Die ForgingFullering & edging are used to distribute the materialFullering material is distributed away from an areaEdging material is gathered into an area

Blocking rough shaping of the part

Impression dies give the part its final shape

Precision ForgingUsed for economic reasonsThe part formed is close to the final dimensionsLess machining is neededHigher capacity equipment is neededAluminum and Magnesium alloys work well in the process

Coining Closed-die forging process

Used for minting coins, medallions, & jewelryLubricants can not be used in coiningCan be used to improve surface finish

Upset ForgingIncreasing the diameter of a length through compressionTypically used for fastenersForging motion is usually horizontal and the workpiece is moved from station to station rapidly Generally employs multiple-cavity dies

Rules for Upset ForgingThe length of unsupported metal that can be gathered or upset in one blow without injurious buckling should be limited to three times the diameter of the barLength of stock greater than three times the diameter can be successfully upset provided that the upset dia is not more than one times the diameter of the barIn the conditions of rule 2, the length of unsupported metal beyond the face of the die must not exceed the dia of the bar

Roll ForgingRound or flat bar stock is reduced in thickness (cross section) and increased in length Typical products include axles, tapered levers and leaf springs

Swaging (Radial Forging)Uses external hammering to reduce the diameter or produce tapers on round bars or tubes