McGuire Glossary of Fastener Terminology

E - 102 terms

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

ECCENTRIC PRESS - A mechanical press in which an eccentric, instead of a crankshaft, it is used to move the ram.

ECCENTRIC, ECCENTRICITY - Two surfaces of a fastener are eccentric when they do not have the same center or axis. The amount by which the centers or axes are displaced from each other is called eccentricity. This is not to be confused with Total Indicator Reading (TIR)

EDDY-CURRENT TEST - Nondestructive testing method in which eddy-current is induced in the test object. Changes in the flow cause by variation in the object are reflected into a nearby coil or coils for subsequent analysis by suitable instrumentation and techniques.

EDGE BULGE - Condition resulting from any forming, piercing, hardware insertion or spot welding operation too close to an edge.

EDGE DISTANCE - The distance from centerline to centerline of an anchor from an unsupported edge of the base material.

EDGE DISTANCE: CRITICAL EDGE DISTANCE - The least edge distance at which the allowable load capacity of an anchor is applicable without reductions.

EDGE DISTANCE: MINIMUM EDGE DISTANCE - The least edge distance at which the anchors are tested for recognition.

EDGE FINDER - A device used to find the exact edge of a workpiece along the x or y axis.

EDGE-TO-FEATURE - Dimension between the edge of the part and a feature.

EDGER (EDGING IMPRESSION) - The portion of the die impression that distributes metal, during forging, into areas where it is most needed to facilitate filling the cavities of subsequent impressions to be used in the forging sequence.

EDGEWINDING - Retaining Ring manufacturer Smalley's manufacturing method of circle coiling rectangular section flat wire on edge.

EDGING - The forging operation of working a bar between contoured dies while turning it 90 degrees between blows to produce a varying rectangular cross section.

EDGING/EDGE ROLLING - Curling the edge of a metal component into a circular cross-section. Edge rolling is typically used to remove sharp and dangerous burrs.

EFFECTIVE DIAMETER - This is the diameter of an imaginary cylinder coaxial with the thread, which has equal metal and space widths. It is often referred to as pitch diameter. Sometimes referred to as the simple effective diameter to differentiate from the virtual effective diameter.

EFFECTIVE EMBEDMENT DEPTH - The dimension measured from the concrete surface to the deepest point at which the anchor tension load is transferred to the concrete.

EFFECTIVE NUT DIAMETER - Twice the effective nut radius.

EFFECTIVE NUT RADIUS - The radius from the centre of the nut to the point where the contact forces, generated when the nut is turned, can be considered to act.

EFFECTIVE THREAD - The effective (or useful) thread includes the complete thread and that portion of the incomplete thread having crests not fully formed.

EFFECTIVE TORQUE - A torque in excess of any running torque.

EFFECTIVE TRANSFER LENGTH - This is the length of the part being transferred combined with the location of the punch at front dead center at the delivery station. This length is used as a check to make sure a part may be transferred from one station to another without interference by the tooling.

EFFICIENCY (FORGING) - The amount of applied energy, in percentage, that is employed in deforming the workpiece to the total energy expended by the forging equipment.

EJECTOR - Also known as knockout. Heat treated steel rods located within the dies and operated by the press action to remove a completed forging after the forging cycle.

ELASTIC INTERACTION - Occurs when multiple bolts in a joint are not tightened simultaneously. Once a first bolt is tightened, the fastener stretches and the joint is partially compressed. When an adjacent bolt is tightened, the joint in the vicinity of the first bolt is further compressed, allowing the first bolt to relax.

ELASTIC LIMIT - The maximum load per unit of area (usually stated as pounds per square inch) that may be applied without producing permanent deformation. It is common practice to apply the load at a constant rate of increase and measure the increase of length of the specimen at uniform load increments. The point at which the increase in length of the specimen ceases to bear a constant ratio to the increase in load, is called the proportional limit.

ELASTIC LIMIT - The maximum stress to which a material may be subjected to without permanent set.

ELASTIC RANGE - The range in which a material can be deformed and still return to its original shape.

ELASTOMER - Any synthetic or natural material with a resilience characteristic or "memory" sufficient to cause it to return to its original shape or form after major or mine distortion.

ELECTRICAL CONDUCTIVITY - Metals carry electric currents with varying capacities. Copper, brass, stainless, silicon bronze as common fasteners that need attention to the electrical conductivity in the fastener design application stage.

ELECTRO FORMING - Production or reproduction of articles by electrodeposition upon a mandril or former or mould which is as a rule subsequently separated from the deposit.

ELECTRO-GALVANIZING - The process of coating metal with zinc by electroplating.

ELECTRO-POLISHING - The improvement in the surface finish of a metal effected by making it anodic in an appropriate solution.

ELECTRODE - A term denoting anode or cathode.

ELECTRODEPOSITION - The process of depositing a substance upon an electrode by electrolysis. Electrodeposition includes electroplating, electroforming, electrorefining and electrowinning.

ELECTROLESS NICKEL - A relatively thin, hard coasting that can be applied to threads and deposited uniformly. Bright metallic in appearance this coating has excellent resistance to wear and corrosion.

ELECTROLESS NICKEL - Electroless nickel is an auto-catalytic reaction used to deposit a coating of nickel on a substance. Even coatings on parts surface can be achieved and flexibility in plating volume and thickness are advantages.

ELECTROLESS PLATING - Term in use, but not recommended for autocatelytic plating.

ELECTROLYTE - An electrically conductive fluid or substance.

ELECTROLYTE (COLLOQUIAL USE IN ELECTROPLATING) - Any conducting solution used for plating or anodizing baths.

ELECTROLYTIC CLEANING - Cleaning by immersion without the use of current usually in an alkaline solution.

ELECTROPLATING - The deposition of a metallic coating onto an object by putting a negative charge onto the object and immersing it into a solution which contains a salt of the metal to be deposited. The metallic icons of the salt carry a positive charge and are attracted to the part. When they reach it, the negatively charged part provides the electrons to reduce the positively charged icons to metallic form.

ELECTROPLATING - The deposition of an adherent metallic coating upon an electrode for the purpose of securing a surface with properties or dimensions different from those of the basis metal.

ELECTROPLATING RANGE - The current density range over which a satisfactory electrodeposit can be obtained.

ELECTROPOLISHING - The smoothening of brightening of a metal surface by making it anodic in an appropriate solution.

ELECTROSLAG REMELTING (ESR) - A process of refining metal in which metal is re-melted through a layer of slag from a consumable electrode form. Alloys that are refined through EST have better uniformity, are better for forging, and have superior properties to other metals.

ELECTROSTATIC COATING - A manufacturing process that employs charged particles to more efficiently paint a workpiece. Paint, in the form of either powdered particles or atomized liquid, is initially projected towards a conductive workpiece using normal sprayng methods, and is then accelerated towards the work piece by a powerful electrostatic charge. An addition to the eletrostatic coating (or e-coating) process is dipping electrically conductive parts into a tank of paint that is then electrostatically charged.

ELEMENT - Elements of a thread are flank angle, root, crest, pitch, lead angle, surface finish, major, minor, and pitch diameters

ELLIPTICAL LOCK - A thread lock created by deforming a portion of an internally threaded fastener into an elliptical shape.

ELONGATION - The increase in length of a test specimen after rupture in a tensile test, expressed as a percentage of the original length. Typically decreases as strength and hardness increase.

EMBEDMENT - Localized plastic deformation which occurs in the vicinity of clamped fasteners or in the fastener threads. Embedding is local plastic deformation that occur under the nut face, in the joint faces and in the threads as a result of plastic flattening of the surface roughness. This occurs even when the loading is below the yield point of the bolt or limiting surface pressure of the joint material and is the result of the real area of contact between surfaces being less than the apparent areas.

EMBEDMENT DEPTH - The distance from the top-surface of the base material to the installed end of the anchor. In case of a post-installed mechanical anchor, the embedment depth is measured prior to application of the installation torque.

EMBEDMENT RELAXATION - Yielding that occurs when bolts are tightened. When a bolt is tightened, the threads contact each other on microscopic high points. These highpoints are overloaded and will yield causing the bolt to relax. In some cases, 5% to 10% of the initial bolt load can be lost due to embedment relaxation.

EMBOSS - To raise the metal (as to emboss a trade mark or code on screw heads).

EMBOSSING - The process of raising a boss or protuberance on the surface.

EMBOSSING - Blanks can be embossed by both raising and recessing the sheet metal components. Embossing is a process referring to the creation of recessions or protrusions in the component, which is achieved by passing the blank along a roller die or against a die with the desired shape.

EMBRITTLEMENT - The severe loss of ductility or toughness or both of a material, usually a metal or alloy. Many forms of embrittlement can lead to brittle fracture. Many forms can occur during thermal treatment or elevated-temperature service (thermally induced embrittlement).

EMBRITTLEMENT - The severe loss of ductility or toughness or both of a material, usually a metal or alloy. Many forms of embrittlement can lead to brittle fracture. Many forms can occur during thermal treatment or elevated-temperature service (thermally induced embrittlement).

EMULSIFYING AGENT EMULSIFIER - A substance used to produce a stable emulsion.

EN - European Organization of Standardization

ENCIRONMENTALLY ASSISTED CRACKING (EAC) - A process that can occur with the use of high strength steel fasteners in which crack initiation and growth occurs in the fastener at a comparatively low stress level as a result of interactions that occur with the environment. Hydrogen is suspected of causing EAC in high strength steel fasteners, the hydrogen being produced as a result of chemical reactions (galvanic corrosion in a moist environment) or being present from a plating process that may have been applied to the fastener.

ENCLOSED UPSET - The upset material is totally contained with the tooling cavity at the end of the forming stock Also see UPSET.

END FIXATION FACTOR - A factor used in the calculation of buckling to take account of the method of locating the ends of the spring

END LOAD - The axial force applied to a driving tool by the operator, usually required in applying torque to a recessed fastener.

END LOSS (CROP END) - Bar end left over after cutting bar lengths of stock into forging multiples.

END MILL - Cutters used in milling machines. Types of End Mills, include standard, ball nose and double ended.

ENDURANCE LIMIT - The maximum stress that a fastener can withstand without failure for a specified number of stress cycles (also called fatigue limit).

ENERGY - Work as a function of the forming load throughout the forming stroke, This supplied by the motor and is used to form the parts in each station. If more energy is consumed by all forming operations than the motor can re-supply for the next forming stroke, then the machine will slow down and possibly stop. It is expressed in ether Foot-Pounds or Joules.

ENFOLATION - The lap that can be formed at the thread crest due to thread rolling.

ENGAGEMENT - A measurement of how much of a fastener is in the material being fastened. Thread Engagement is a design engineering term.

ENGAGEMENT, THREAD - The axial length over which mating complete threads are in contact

ENTERPRISE RESOURCE PLANNING (ERP) - ERP adapts the techniques of MRPII to all areas of an organization (as opposed to the manufacturing arena.) ERP is usually implemented as a comprehensive business software solution

ENVIRONMENTAL HYDROGEN EMBRITTLEMENT - Hydrogen embrittlement caused by the hydrogen introduced to the fastener after it is placed in service.

ENVIRONMENTALLY ASSISTED CRACKING (EAC) - A process that can occur with the use of high strength steel fasteners in which crack initiation and growth occurs in the fastener at a comparatively low stress level as a result of interactions that occur with the environment. Hydrogen is suspected of causing EAC in high strength steel fasteners, the hydrogen being produced as a result of chemical reactions (galvanic corrosion in a moist environments) or being present from a plating process that may have been applied to the fastener.

EP ADDITIVE - An (Extreme Pressure) additive for the liquid die lubricant. Helps to perform the various forming operations and prevents galling of the part or tooling.

ERROR-PROOFING - A technique for preventing production errors by designing the manufacturing process, equipment and tools so that an operation literally cannot be preformed incorrectly (See Poka-Yoke)

ERTALYTE (PET) (PLASTICS) - Polyethylene terephthalate is a clear, crystalline plastic possesssingd high strength and low vapor permeability. Because it is also sterilizable and radiation resistant, it is used extensively as a container for carbonated beverages, liquor and other food products. It is also generally approved for use in the processing and packaging of pharmaceuticals.

ETCH - A chemical process that cleans and brightens aluminum after heat treatment.

ETCH - To roughen the surface of a metal by selective dissolution.

ETCH TEST - The process of revealing the macro-structure of metals by preferential attack of a prepared surface by a suitable reagent.

ETCHANT - The solution used for etching.

EUTECTIC - An isothermal reversible reaction in which a liquid solution is converted into two or more intimately mixed solids on cooling, the number of solids formed being the same as the number of components in the system. (2) An alloy having the composition indicated by the eutectic point on an equilibrium diagram. (3) An alloy structure of intermixed solid constituents formed by a eutectic reaction.

EUTECTIC ALLOY - The alloy composition that freezes at constant temperature similar to a pure metal. The lowest melting (or freezing) combination of two or more metals. The alloy structure (homogeneous) of two or more solid phases formed from the liquid eutectically.

EVOP - Stands for evolutionary operations in experimental design.

EXCESSIVE BEARING STRESS - If the surface stress caused by clamp load is too high, surface collapse occurs resulting in a loss of bolt strength and so a loss of preload.

EXOTIC FASTENER MATERIALS - Various fastener materials used for applications that might have high or low temperatures, extreme environment conditions, high corrosive atmospheres. Common exotic materials are Hastelloy, Tantalum, Titanium, Inconel, Waspaloy and, Zirconium, among others.

EXPANDING - A hollow forging operation whereby the diameters are increased by reducing wall thickness with relatively little increase in length by working on a mandrel.

EXPANSION ANCHOR - A mechanical fastener placed in hardened concrete or masonry to expand in a self-drilled or pre-drilled hole of a specific size and engagement in the hole in one or more locations to develop shear and/or tension resistant loads without grout or adhesive.

EXTENSION SPRING - A spring that absorbs and stores energy while offering resistance to being pulled.

EXTENSION SPRING - (Also known as Tension Spring) A spring whose length, in the direction of the applied force, increases under the application of that force.

EXTENSOMETER - This device measures the linear deformation of a fastener to sense the elongation under tensile stress in a controlled test environment.

EXTERNAL FORCE OR LOAD - Forces exerted on a fastener as a result of an applied loading to the joint.

EXTERNAL THREAD - A screw thread which is formed on an external cylinder, such as on bolts, screws, studs, etc.

EXTERNAL TORX - An external Torx screw has a projecting head in the shape of a Torx screwdriver bit (instead of a standard recessed cavity): a Torx socket is used to drive it.

EXTERNALLY RELIEVED BODY - A body on which the diameter of the entire body or a portion thereof is reduced to less than the minimum pitch diameter of the thread.

EXTRUDING - The process of reducing the size of some feature or diameter by forcing it through a die. Extrusion produces long, continuous shapes that may not vary in cross section over the length.

EXTRUSION - The process of forcing metal to flow through a die orifice in the same direction in which energy is being applied (forward extrusion); or in the reverse direction (backward extrusion), in which case the metal usually follows the contour of the punch or moving forming tool. The extrusion principle is used in many impression die forging applications.

EXTRUSION DEFECT - A metal slug used as extrusion stock.

EXTRUSION LAND - The smallest diameter of a forward extrusion die that forms an orifice for the metal to flow through or the diameter on a backward extrusion punch or pin that determines the diameter of the formed hole.

EXTRUSION PIN / PUNCH - A tooling component that forms the hole in a backward extruded part.

EXTRUSION PIPE - A central oxide-lined discontinuity that occasionally occurs in the last 10 to 20 percent of an extruded bar. It is caused by the oxidized outer surface of the billet flowing around the end of the billet and into the center of the bar during the final stages of extrusion. Also called Coring.

EXTRUSION PUNCH HOLDER - This is a special first station punch holder used on Three Blow-Two Die Headers. It carries the punch used for the trapped extrusion in the first die on those machines.

EYELET - A flanged tubular fastener designed for securing by curling or splaying the tubular end.