McGuire Glossary of Fastener Terminology

I - 86 terms

I-PRESS - An electronic and automated press control system for mechanical and hydraulic presses. This system allow operators to electronically extract job data, remotely monitor pressing operations, download data from other projects. etc.

IAPMO - Uniform Evaluation Service . An ISO 17065 ANSI-accredited company that issues evaluation reports expressing a professional opinion as to a products building code compliance

IBC - International Building Code

ID - Inside Diameter. OD - (2 x wire size)

IFI - Industrial Fastener Institute

IFO - An abbreviation for (Individual Finger Opening). These are the adjustable cams used to open and close the transfer fingers at each transfer station.

IMMERSION PLATING - The production of an immersion deposit.

IMMUNIZE - To remove small particles of iron or grit from the surface of stainless steel by pickling in an acid solution.

IMPACT EXTRUSION - A reverse extrusion process in which metal is displaced backwards between a punch and a die to form a hollow part.

IMPACT TEST - A test to determine the energy absorbed in fracturing a test bar at high velocity. The test may be in tension or in bending, or it may properly be a notch test if a notch is present, creating multiaxial stresses.

IMPACT TEST - Test to determine the energy absorbed in fracturing a notched test bar at high velocity. See Charpy Test & Izod Test

IMPACT VELOCITY - The relative velocity of the forging dies just prior to impact.

IMPACT WRENCH - A wrench, usually powered by electricity or air, in which repeated blows from little hammers are used to generate torque to tighten fastener, The torque applied to the fastener depends upon the time and the air pressure applied to the tool (pneumatic wrenches). The torque applied by an impact wrench to a fastener in influenced by the joint stiffness.

IMPRESSION - A cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging.

IMPRESSION - To make a mark into the metal

IMPRESSION DIE FORGING - A forging that is formed to the required shape and size by machined impressions in specialty prepared dies that exert three-dimensional control on the workpiece.

IN PROCESS SAMPLING (SPC) - A typical production inspection technique in which a pre-determined number of random samples is pulled from the production line and dimensionally inspected or mechanically if required.

IN-PROCESS SAMPLING - Random samples of fasteners taken at different points in the manufacture for testing conformance.

INACTIVE COILS (SPRING TERM) - Coils which are not free to deflect under load and do not contribute to the rate of a spring

INCHING - An operating mode whereby a series of cemental motions are used to adjust a set of dies and tools. Inching is used to precisely control the slide and other working members of the press.

INCLUDED ANGLE OF THREAD - The angle between the flanks of the thread measured in an axial plane.

INCLUSION RATING (ASTM E45) - This test identifies the inclusion content of steel. Inclusions are characterized by size, shape, concentration, and distribution, rather than chemical composition. Although compositions are not identified, the microscopic method places inclusions into one of several composition-related categories - sulfides, oxides and silicates.

INCLUSIONS - Particles of non-metallic impurities contained in material.

INCLUSIONS - Particles of nonmetallic compounds of metals and impurity elements that are present in ingots and are carried over in wrought products. The shape and distribution of inclusions are changed by plastic deformation and contribute to directionality in metals.

INCOMPLETE THREAD - Threads having crests or roots not fully formed. Incomplete threads occur at the end of pointed eternally threaded products, at countersinks in the faces of threaded holes or nuts, and at thread runouts where the threaded section blends into the unthreaded shank

INCOMPLETE THREAD - This is also known as the vanish or washout thread. On straight threads, the incomplete thread is that portion at the end having roots not full formed by the lead or chamfer on threading tools. On taper threads, the crest at the end also may be not fully formed due to the intersection of the major cone of an external thread or the minor cone of an internal thread with the cylindrical surface of the work.

INCONEL - Nickel-Chromium-Iron alloy (not to be confused with 18-8 Stainless Steel). Approximately 77% Nickel and 15% Chromium. Exotic material with good corrosion resistance at high temperatures and superior strength.

INCONEL 718 - Inconel 718 is an age (precipitation) hardened alloy that retains its high yield strength and usability to 1800 degrees F. Good creep and rupture strength with a high resistance to fatigue. Used in rocket engine components.

INDENT - To form a slight recess. Usually an operation in preparation for further forming or to assist in transferring the part.

INDENTED HEX HEAD - Have an indented top surface, six flat sides, and a flat bearing surface. Preferred in high volume assembly where pneumatic equipment is used to drive the screw. Can transmit significantly higher tightening torque levels tan other head styles.

INDENTED HEX WASHER - Has an indented top surface, six flat sides with a flat washer which projects beyond the sides and provides a flat bearing surface. The washer and hex are formed together as one piece. Also available with a slot feature. Increased bearing surface reduces likelihood of crushing mating surfaces.

INDEX (SPRING TERM) - The ratio of the mean coil diameter (M) to either the material diameter (d), for circular sections, or the radial width of the cross section for rectangular or trapezoidal sections.

INDUCTION HARDENED - A heat treated fastener that has undergone a selective hardening process, using induction coils, to further strengthen a part of the fastener.

INDUCTION HARDENING - A surface-hardening process in which only the surface of a suitable ferrous workpiece is heated by electromagnetic induction to above the upper critical temperature and immediately quenched.

INDUCTION HARDENING - A surface-hardening process in which only the surface layer of a suitable ferrous workpiece is heated by electromagnetic induction to above the upper critical temperature and immediately quenched.

INDUCTION HEATING - Heating by combined electrical resistance and hysteresis losses induced by subjecting a metal to the varying magnetic field surrounding a coil carrying alternating current.

INDUCTION HEATING - Heating metals by means of an alternating magnetic field.

INGOT - A casting intended for subsequent rolling, forging, or extrusion.

INGOTISM - A term used to describe the remnants of dendritic structure which may occasionally be found in forgings.

INHIBITOR - A substance used to reduce the rate of a specific chemical or electro-chemical reaction, for example: Pickling inhibitor.

INITIAL TENSION - Force that holds the coils tightly together

INITIAL TENSION (FO) - The force that tends to keep the coils of an extension spring closed and which must be overcome before the coils start to open.

INJECTION MOLDING - Creating a shape by injecting a material into a cavity where the injected material fully fills the cavity under pressure. When pressure is relieved, the part is ejected from the cavity. The final part will retain the shape of the cavity. Typically, the materials are nylon or plastic.

INLINE TOOL CONFIGURATION - Straight tools are suitable for screw-driving applications where the applied torque is relatively low. They are also useful in higher torque applications when the tool is fixtured to absorb the torque reaction or equipped with a torque-reaction bar. The reaction bar is placed against a solid support to absorb the torque-reaction impulse.

INNSIDE DIAMETER (I.D.) (SPRING TERM) - The diameter of the cylindrical envelope formed by the inside surface of the spring coils.

INSERT - A piece of steel that is tightly fixe in a die. The insert may be used to fill a cavity, to replace a portion of the die with a grade of steel that is better suited for service at the point, or to function as a small die with the impression fastened to a master die.

INSERT - A tooling component made from a hard, wear resistant material and pressed into a case for support. This component is in direct contact with the formed piece.

INSERT DIE - A relatively small die containing part or all of the impression of a forging, and which is fitted to the master die block by means of a key.

INSERTS (CNC) - Inserts are cutting tips made of carbide, diamond, ceramic or other materials, which can be easily inserted onto a cutting tool so you don't have to remove and replace the entire tool when a tip becomes dull.

INSIDE DIAMETER - The interior surface of a spherical or cylindrical object.

INSIDE HOOK LENGTH - Length from the inside of the hooks or loops.

INSOLUBLE ANODE - An anode which does not contribute metal ions to the electrolyte during electrolysis.

INSPECTION CRITERIA - Characteristics by which the part will be evaluated both dimensionally and cosmetically.

INSTALLATION FORCE - A term expressed in Pounds, Tons, or Newtons applied to achieve proper fastener installation.

INSTALLATION FORCE - Also known as "On-Torque". Highest value of prevailing or running torque exhibited by a part while installing or engaging to the mating thread form prior to start of any axial load (pre-load).

INSTALLATION LOAD - The force required to completely form the bulb during installation. Thick wall parts have higher installation loads than thin wall parts. The installation mandrel must transmit the installation load and therefore blind threaded fasteners are typically not offered in sizes smaller than 4-40 or M3. Also know as upset load.

INSTALLATION STRESS (SC) OR (SE) - mathematical expression on a redial strain. Useful in determining how far a Spirolox Retaining Ring can be expanded or contracted during installation.

INSTALLATION TOOL - The tooling used to install a fastener. Can be hand operated or powered.

INSTALLATION TORQUE - The highest value of prevailing torque produced the first time the self-locking fastener is being installed. This is taken during the first five revolutions after engaging the locking element and before seating. NYLOK

INSTALLATION TORQUE - The highest value of prevailing torque produced the first time the self-locking fastener is being installed. This is taken during the first five revolutions after engaing the locking element and before seating.

INSTALLED GAP (SEE FREE GAP) - This ring dimension is the distance between the ring ends while the ring is restrained at a specific gage diameter. Recommended as a more precise method of control over a free gap.

INSTANANEOUS CENTRE OF ROTATION - The point in space that an eccentrically shear loaded joint rotates about. The deformation and the load sustained by an individual bolt in a bolt group is dependent upon the distance that the bolt is from the instantaneous center. The direction that the individual bolt force acts is perpendicular to a line joining the bolt to the instantaneous center.

INTEGRAL FASTENER - A term used to describe types of fasteners which are highly resistant to vibration loosening and/or removal. Some types have special thread forms.

INTERFERENCE FIT - A thread fit having limits of size so prescribed that an interference always results when mating parts are assembled.

INTERFERENCE FIT - The difference in diameters between a case and an insert that is assembled into the case. The outside diameter of the insert is larger than the inside diameter of the case. This gives support to the inside diameter of the insert during the forming process.

INTERGRANULAR CORROSION - Electrochemical corrosion along the grain boundaries of an alloy, usually caused because the boundary regions contain material anodic to the center of the grain.

INTERMEDIATE ANNEALING - Annealing at one or more stages during manufacture and before final thermal treatment.

INTERNAL AIR / OIL - Special machining to allow for the introduction of either compressed air or liquid die lubricant directly into the tool or die.

INTERNAL HYDROGEN EMBRITTLEMENT - Hydrogen embrittlement that results from the manufacturing process and not an outside source.

INTERNAL THREAD - A screw thread which is formed in holes, such as in nuts, or inside a hole.

INTERNAL WRENCHING BOLT - A bolt have a large cylindrical head with flat top, flat bearing surface, and hexagon socket. The bolt is known as a socket head cap screw. A bolt designated as an Internal Wrenching bolt is used in aircraft. It is similar in design to the one previous described except that the head is tapered.

INTERNALLY RELIEVED BODY - A body which has an axial hole drilled through a portion of the body.

INTERNATIONAL (MEASUREMENT) STANDARD - This is a standard recognized by an international agreement to serve internationally as the basis for fixing the value of all other standard of the quantity concerned.

INTERNATIONAL METRIC THREAD SYSTEM - A thread form like the American standard, excepting the depth which is greater. There is a clearance between the root and mating crest fixed at a maximum of 1/16 the height of the fundamental triangle or 0.054 x pitch. A rounded root profile is recommended. The angle in the plane of the axis is 60 degrees and the crest have a flat like the American Standard equal to 0.125 x pitch.

INVENTORY TERMS - The number of times inventory is consumed in a given period.

ION EXCHANGE - A reversible process by which ions are interchanged between a solid and a liquid without substantial structural changes of the solid.

ION NITRIDING - A method of surface hardening in which nitrogen ions are diffused into a workpiece in a vacuum through the use of high-voltage electrical energy. Synonymous with plasma nitriding or glow dischargen nitriding.

ION NITRIDING - A method of surface hardening in which nitrogen ions are diffused into a workpiece in a vacuum through the use of high-voltage electrical energy. Synonymous with plasma nitriding or glow-discharge nitriding.

IRONING - A sheet metal forming process wherein the thickness of a workpiece is reduced uniformly.

ISO - The International Organization of Standardization. It is an international standard setting body composed of representatives from a variety of national standards organizations.

ISO 9001 - Quality Management Systems is a set of standards that helps organizations ensure they met customers' needs within statutory and regulatory requirements related to a product or service.

ISO METRIC THREAD - A standard thread form based on millimeters that was developed for use in Europe.

ISOPLAST(R) (PLASTICS) - Isoplast urenthane resins are high tensile stength, chemically resistant resins orginally developed for medical use. They are available in long glass fibre-filled grades. Isoplast(r) combines the toughtness and dimensional stability of amorphous resins with the chemcial resistance of crystalline materials. The long fibre reinfored grades are stong enough to replace some metals in load bearing applications.

ISOTHERMAL FORGING - A hot-forging process in which a constant and uniform temperature is maintained in the workpiece during forging by heating the dies to the same temperature as the workpiece. Most commonly conducted at about 2000 degrees F under a controlled atomsphere or in a vacuum to prevent oxidation while forging superalloys.

ISOTHERMAL TRANSFORMATION - A change in phase at constant temperature.

IZOD IMPACT TEST - A pendulum-type impact test in which the specimen is supported at one end as a cantilever beam and the energy required to break off the free end by the impact of a falling pendulum is used as a measure of impact strength. See Charpy Impact Test.