Forging of Metals

Introduction

A metal is shaped by compressive forces Oldest metal working process – 4000BC Can be performed with a hammer and anvil Typical forged products:

Bolts Rivets Connecting rods Gears

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 strength High toughness Forgings require additional heat treating

Fig : A part made by three different procedures, showing grain flow (a) casting (b) machining (c) forging

Open-Die Forging

Is the simplest forging process Sizes can very from very small parts to very large parts

Open-Die Forging

Upsetting or flat-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

interfaces Can be minimized if a lubricant is used Thermal effects caused by barreling can be minimized

by using heated dies

Open-Die Forging

Forging force

Impression-Die & Closed-Die Forging

The workpiece acquires the shape of the die cavities while being forged between the two shaped dies

Impression-Die & Closed-Die Forging

The blank to be forged is prepared by: Cutting from a bar stock Preformed blank Casting Preformed blank from prior forging

Impression-Die & Closed-Die Forging

Fullering & edging are used to distribute the material Fullering – material is distributed away from an area Edging – material is gathered into an area

Blocking – rough shaping of the part

Impression dies – give the part its final shape

Precision ForgingPrecision Forging

Used for economic reasons The part formed is close to the final dimensions Less machining is needed Higher capacity equipment is needed Aluminum and Magnesium alloys work well in the process

CoiningCoining Closed-die forging process

Used for minting coins, medallions, & jewelry Lubricants can not be used in coining Can be used to improve surface finish

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