Forging

Workshop TechnologyME-121 (1-2 Cr. Hr.)

Mansoor Ghazi, Department of Mechanical EngineeringCollege of E&ME, NUST Pakistan

What You Will Learn

• What is forging • Various forging techniques• Equipment for forging• A bit of math behind forging (analysis)• Some simple examples

What is Forging

• A metal forming technique used to shape metals by application of local compressive forces.

• Compressive forces can be generated in a metal either through impact (with hammers) or by gradually pressing (with presses).

• Forging is typically used to establish a basic/initial shape of a part.

Forging Illustrated

Manual Hammer Forging

Drop Hammer Forging

Press Forging

Forging and Temperature

• Metal can be shaped at both low and high temperatures by appropriate application of force/pressure.

• Based upon temperature forging is classified as:– Hot or Warm Working: Requires less force/pressure.

Increases ductility but reduces strength– Cold Working: Increases strength but requires

greater forces/pressure

Dies and Types of Forging

• Dies are used to constraint the workpiece between two or more surfaces while force is being applied to it.

• Based on the type of die being used, forging can be classified as:– Open Die Forging– Impression Die Forging– Flashless Forging

Types of Forging Dies

Open Die Forging

•It involves compression of a workpiece between two flat dies and is similar to compression testing. At times the dies are not purely flat.•Resulting deformation reduces the height but increases the cross section of a workpiece.•Such a deformation process is also known as upsetting or upset forging.•If no friction occurs between the die and workpiece under compression, a uniform deformation occurs in which radial flow is uniform throughout the workpiece height.

Open Die Forging with Friction

•In the absence of a lubricant, friction between the workpiece and die surfaces pops up.•Due to friction between the workpiece and die surfaces, metal flow becomes non-uniform.•Consider the example of water flowing in a river; water flows faster in the center and slower near the river bank.•In hot forging, friction effects are even more pronounced.

Impression Die Forging

Impression Die Forging

• Advantages– Higher production rates– Less material wastage – Higher Strength and Strength to Weight Ratios– Favorable grain orientation in the metal crystalline

structure• Disadvantages– Not capable of close tolerances– Machining is often required to achieve the desired

level of final accuracy and features

Trimming

Flash less Forging

Flash less Forging

Upsetting and Heading

Upsetting and Heading Cont.

Swaging and Radial Forging

Forging Hammers

Forging Presses

Some Math Behind Forging

Analysis of Hot Forging

Analysis of Hot Forging Cont.

Analysis of Hot Forging Cont.

Analysis of Hot Forging Cont.

Let’s Analyze !

• Cold Upsetting Example:

• Hot Upsetting Example:

Time To Get Your Hand’s Dirty !