Z94.12.4 Metal Forming

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EAR. A wavy projection formed in the course of deep drawing as a result of directional properties or anisotropy of the sheet.

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.

EJECTOR. A mechanism for removing work or material from between the dies.

ELASTIC LIMIT. The maximum stress a metal can withstand without exhibiting a permanent deformation upon complete release of the stress. Since the elastic limit may be determined only by successively loading and unloading a test specimen, it is more practical to determine the stress at which Hooke's law (deformation is proportional to stress) no longer holds. It must be remembered that repeated loads which produce any degree of permanent deformation also produce strain-hardening effects in most metals, which in turn, increase the elastic range for load applications after the initial one. The point above which the ratio of stress to strain is no longer constant is called the "proportional limit.'' It is customary to accept the value of this point as the equivalent of the so-called "elastic limit.''

ELONGATION. The amount of permanent extension in the vicinity of the fracture in the tension test; usually expressed as a percentage of the original gage length, such as 25% in 2 inches.

EMBOSSING. A process for producing raised or sunken designs in sheet material by means of male and female dies. Common examples are letters, ornamental pictures and stiffening ribs.

ENDURANCE LIMIT. The maximum stress that a metal can withstand without failure during a specified large number of cycles of stress. If the term is employed without qualification, the cycles of stress are usually such that they produce complete reversal of flexural stress.

ENERGY CURVE. A graphical representation to show available flywheel energy as a function of stroke rate on a variable-speed press.

ENGINEERING STRESS. The load per unit area necessary to elongate a specimen. Computation is based on original cross-sectional area.

EXTRUSION. Shaping metal into a chosen continuous form by forcing it through a die of appropriate shape.

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