earing

The formation of ears or scalloped edges around the top of a drawn shell, resulting from directional differences in the plastic-working properties of rolled metal with, across, and at angles to the direction of rolling. (See Figure E1)

eberly screw

See chicago screw.

eccentric

The offset portion of the driveshaft that governs the stroke or distance the crosshead moves on a mechanical or manual shear.

eccentric gear

A main press-drive gear with an eccentrics as an integral part.  The unit rotates about a common shaft, with the eccentric transmitting the rotary motion of the gear into the vertical motion of the slide through a connection.

eccentric press

A mechanical press in which an eccentric, instead of a crankshaft, is used to move the slide.

edger (edging impression)

The portion of a die impression that distributes metal during forging into areas where it is most needed in order to facilitate filling the cavities of subsequent impressions to be used in the forging sequence.

edging

(1) In sheet metal forming, reducing the flange radius by retracting the forming punch a small amount after the stroke but before release of the pressure. (2) In rolling, the working of metal in which the axis of the roll is parallel to the thickness dimension.  Also called edge rolling. (3) The forging operation of working a bar between contoured dies while turning it 90' between blows to produce a varying rectangular cross section.

effective draw

The maximum limits of forming depth that can be achieved with a multiple-action press; sometimes called maximum draw or maximum depth of draw.

ejecting

The removal of a part from a die by an air blast or mechanical means.

ejector

A mechanism for removing a part from a die.  Also called kicker or knock-out.

ejector rod

A rod used to push out a formed piece.

elastic deformation

A change in dimensions that is directly proportional to and in phase with an increase or decrease in applied force; deformation which is recoverable when the applied force is removed.

elastic instabilities

A section of a part which has two equilibrium positions and can be manually switched between each position.  Elastic instabilities are created when a highly deformed area is constrained on all sides by regions of less deformed areas.  Elastic instabilities are also referred to as oil canning.  See Figure E2 for a schematic of an elastic instability.

elastic limit

The maximum stress a material can sustain without any permanent strain (deformation) remaining upon complete release of the stress.  See also proportional limit.

elasticity

The property of a material by which the deformation caused by stress disappears upon removal of the stress.  A perfectly elastic body completely recovers its original shape and dimensions after the release of stress.

electromagnetic forming

A process for forming metal by the direct application of an intense, transient magnetic field.  The workplace is formed without mechanical contact by the passage of a pulse of electric cur-rent through a forming coil.  Also known as magnetic pulse forming.

elephant ears

Cast or welded projections in the shape of an ear on the outboard section of a die.  They are used for handling the die with chains.

elongation

The amount of permanent extension of the material before it fractures.  Elongation takes place in the part during forming or drawing operations. See also elongation, percent.

elongation, percent

The extension of a uniform section of a specimen expressed as a percentage of the original gage length:

Elongation, % = (L_x - L_o) / L_o x 100

 where L_o is the original gage length and , L_x is the final gage length.

emboss

A relatively shallow indentation or raised design with basically no change in metal thickness.

embossing

A process for producing raised or sunken designs in sheet material by means of male and female dies, theoretically with no change in metal thickness. Examples are letters, ornamental pictures, and ribs for stiffening.  Heavy embossing and coining are similar operations.

embossing die

A die used for producing embossed designs.

equalizer pins

A pin used in conjunction with pressure pins to distribute and balance the load on a die cushion.  Also called balancing pins.

Erichsen test

A cupping test used to assess the ductility of sheet metal.  The method consists of forcing a conical or hemispherical-ended plunger into the specimen and measuring the depth of the impression at fracture.

explosive forming

The shaping of metal parts in which the forming pressure is generated by an explosive charge.  See also high-energy-rate forming

extractor

A mechanism attached to a press for removing a part from a die.  Also called an iron hand.

extruding

(1) The turning up or drawing out of a flange around a hole which has been punched in a previous operation.  Also called hole flanging. (2) The punching and flanging of a hole in one operation generating a slug. (3) The cutting or tearing (piercing) and flanging of a hole in one operation without generating a slug.  Also called spearing or spear punching.

extrusion

A metal forming process which a punch compresses a billet (hot or cold) confined in a container so that the billet material flows through a die in the same direction as the punch.

eye bolt

A bolt having a looped head designed to receive a hook or rope.

eyeleting

The displacing of material about an opening in sheet or plate so that a lip protruding above the surface is formed.