McGuire Glossary of Fastener Terminology

M - 132 terms

MACHINABILITY - The ease that a material can be drilled or cut.

MACHINE FORGING (UPSETTER FORGING) - The process of forging in a forging machine (upsetter) in which the metal is moved into the die impression by pressure applied in a horizontal direction by moving the die in the ram.

MACHINE SCREW ANCHORS - Machine screw anchors are made up of two parts: the internal threaded cone and the outer sleeve. The outer sleeve is made of rest-resistant material Zamack. The internal threaded cone is made from zinc plated low carbon steel.

MACHINED SPECIMEN - This is a test specimen machined from a full-size fastener to specific dimensions to standardize test results; often specified when a full-size fastener cannot be reasonably or practically tested. This test is used to determine elongation and reduction of area.

MACHINING - The process of forming the surface by cutting away material. Often called Mill from a Bar. Machining can interrupt the grain of metal causing a lessening in tensile and fatigue strength.

MACHINING CENTER - A CNC milling and drilling machine that has an automatic tool changer making it capable of performing multiple operations.

MACRO-ETCH (ASTM E340) - Macro-etching provides information on variations in structure, such as grain size, flow lines, columnar structure, dendrites, etc. MACROETCHING ALSO REVELAS THE PRESENCE OF DISCONTINUITIES AND VOIDS, SUCH AS SEAMS, LAPS, POROSITY, FLAKES BURST, EXTRUSION RUPTURE, CRACKS, ETC.

MACROETCH - A testing procedure for conditions such as porosity, inclusions, segregation, carburization, and flow lines from hot working. After applying a suitable etching solution to the polished metal surface, the structure revealed by the action of the reagent can be observed visually. See Etch Test

MACROSTRUCTURE - The structure and condition of metals as revealed on a suitably prepared and etched sample, and visible without the use of a microscope or under low magnification (up to 10 diameters.)

MAGAZINE-FED - Refers to a number of Advel(r) Speed fasteners, which can be handled and loaded into an installation tool as a single item.

MAGNETIC PERMEABILITY - A magnetic permeability test measures a materials ability to become magnetized. When a material is placed in a magnetic field, it interacts with the field in one way or another. If a material is more conductive to the magnetic field, it will have a higher permeability.

MAGNETIC-ANALYSIS INSPECTION - A nondestructive method of inspection for determining the existence and extent of possible defects in ferromagnetic materials. Finely, divided magnet particles, applied to the magnetized part, are attracted to, and outline the pattern of any magnetic leakage fields created by discontinuities.

MAGNETIC-PARTICLE INSPECTION TESTING - A nondestructive method of inspection/testing for determining the existence and extent of possible defects in ferro-magnetic materials. The metal is magnetized, then iron powder is applied. The powder adheres to lines of flux leakage, revealing surface and near-surface discontinuities.

MAGNETISM - 300 series stainless in non-magnetic in its raw material form. Depending on the actual chemical makeup and cold working, magnetism can be present. This rise in magnetism is related to an increase in tensile strength and work hardening caused by heat and friction of cold forming and does not reduce corrosion resistance or cause any molecular change in austenitic raw material.

MAGNIFICATION (GAGING) -

MAGNIFICATION (GAGING) - The visual increase of size that is created by an amplifier. In systems where the air amplifier has adjustable magnification, this is accomplished by adjusting the flow or back pressure within the amplifier to agree with the master sizes. On systems that have air amplifier with fixed magnifications, it is essential tat the air gage tooling is precise so that full amplification can be achieved.

MAJOR DIAMETER - On a straight thread, the diameter of the coaxial cylinder which would pass through the crests of the external thread or the roots of an internal thread.

MALE THREAD - Another name for external threads

MALLEABLE - Capable of being shaped or formed into thin sheets without cracking. Materials can be rolled, hammed, molded, or stamped to achieve the desired effect.

MALLEABLIZING - A process of annealing white cast iron in which the combined carbon is wholly or in parts transformed to graphic or free carbon and, in some cases, part of the carbon removed completely. See Temper Carbon

MANDREL - A specially processed steel rod onto which the magazine of speed fasteners is loaded. Also, the stem/nail section of a break stem fastener.

MANDREL - A blunt-ended tool or rod used to retain or enlarge the cavity in a hollow metal product during forging.

MANDREL - A tooling component that is used to maintain the inside diameter of an extruded hole in subsequent forming operations.

MANDREL - (1) A form used as a cathode in electroforming; a mould or matrix. (2) Support used in bending tests.

MANDREL - The treaded member of the installation tool that engages the threads of the insert and applies the installation load. Spin-spin tools typically use a standard socket head cap screw as the mandrel. Most spin-pull tools use a more comlex mandrel, but some newer tools use a standard socket head cap screw. To install an insert with external threads, the mandrel has internal threads.

MANDREL FORGING - The process of rolling and forging a hollow blank over a mandrel in order to produce a weldless, seamless ring or tube. See Saddle/Mandrel Forging

MANGANESE - A non-magnetic metal which can improve strength and hardness in a fastener.

MANIPULATOR - A mechanical device for handling an ingot or a billet during forging.

MARAGING - A precipitation hardening treatment applied to a special group of iron-base alloys to precipitate one or more intermetallic compound in a matrix of essentially carbon-free martensite.

MARGIN OF SAFETY - A measure of a structure's predicted reserve strength in excess of the design criteria. For a preload fastener, it represents the percentage that the design load (Limit load multiplied by the applicable factor of safety) can increase before the design criteria are no longer satisfied.

MARK FOR PIERCING - A forming operation that forms a sharp corner by shearing to establish satisfactory conditions for the piercing of a slug from a formed part.

MARQUENCHING (Martempering) - (1) A hardening procedure in which an austenitized ferrous workpiece is quenched into an appropriate medium whose temperature is maintained substantially at the Ms of the workpiece, held in the medium until its temperature is uniform throughout - but not long enough to permit bainite to form - then cooled in air. The treatment is frequently followed by tempering. (2) When the process is applied to carburized material, the controlling Ms temperature is that of the case. This variation of the process is frequently called marquenching.

MARQUENCHING (MARTEMPERING) - (1) A hardening procedure in which an austentized ferrous workpiece is quenched into an appropriate medium whose temperature is maintained substantially at the Ms of the workpiece, held in the medium until its temperature is uniform throughout - but not long enough to permit bainite to form - and then cooled in air. The treatment is frequently followed by tempering. (2) When the process is applied to carburized material, the controlling Ms temperature is that of the case. This variation of the process is frequently called marquenching.

MARTEMPERING - A hardening procedure in which an austenitized ferrous workpiece is quenched into a appropriate medium whose temperature is maintained substantially at the Ms of the workpiece, held in the medium until its temperature is uniform throughout but not long enough to permit bainite to form, and then cooled in air. Treatment is followed by tempering.

MARTENSITE - With most steels, cooling as rapidly as possible from their quenching temperature develops a distinctive structure call martensite. In this form, the steel is at its maximum hardness and increased strength capabilities compared to ferrite or austenite.

MARTENSITE - A generic term for microstructures formed by diffusion less phase transformation in which the parent and product phases have a specific crystallographic relationship. Martensite is characterized by an acicular pattern in the microstructure in both ferrous and nonferrous alloys. In alloys where the solute atoms occupy interstitial positions in the martensite lattice (such as carbon in iron), the structure is hard and highly strained; but where the solute atoms occupy substitutional positions (such as nickel in iron), the martensite is soft and ductile. The amount of high-temperature phase that transforms to martensite on cooling depends to a large extent on the lowest temperature attained, there being a rather distinct beginning temperature (Ms) and a temperature at which the transformation is essentially complete (M1).

MARTENSITIC - Martensitic refers mainly to stainless steel types 410, 416 and 420. These grades have a high carbon content which reduces corrosion resistance but allows a sharp increase in tensile strength after heat treatment. Martensitic stainless is magnetic, contains no nickel and loses toughness in very cold temperatures. Its corrosion resistance is not as good austenitic or ferritic stainless steel so these types of fastener are used in mild atmospheres.

MASTER - Wood, metal or plastic reproduction of a proposed forged shape, used to control cutters on tracer-controlled die sinking equipment.

MASTER BLOCK - A forging die block primarily used to hold insert dies.

MASTER DIE - Universal tool receptacle for holding changeable tool systems

MASTER GAGE - A thread-plug gage which represents the physical dimensions of the nominal or basic size of the part. It clearly establishes the minimum size of the threaded hole and the maximum size of the screw at the point at which interference between mating parts begins.

MAT FINISH (MATTE FINISH) - A dull finish

MAT POINT® - A point designed to eliminate cross threading.

MATCH - A condition in which a point in one die half is aligned properly with the corresponding point in the opposite die half within specified tolerance.

MATCHING DRAFT - Increased draft used on the shallow side of a forging to match its surface at the parting line with a similar surface of less draft on the deeper side.

MATERIAL TEST REPORT - A document verifying the raw material meets specified requirements and includes results of mechanical tests and chemical analyses.

MATT FINISH - A uniform finish of a fine texture virtually lacking specular reflectivity.

MAX GRIP - Maximum panel thickness into which a given blind threaded insert can be properly installed. If the panel is thicker than this value there will not be enough free counterbore to form an adequate bulb. It is common practice in the blind threaded insert industry to embed the maximum grip into the end of the part.

MAXIMUM GRIP - The largest recommend thickness of joint material for a fastener.

MAXIMUM MATERIAL CONDITION - The maximum material condition of a feature of a fastener means the maximum amount of material permitted by the tolerance shown for that feature (abbreviated MMC).

MAXIMUM MATERIAL CONDITION - A size condition in which the product contains the maximum amount of material permitted by the specified tolerance. For an internal thread the maximum material condition occurs when all diameters are at the minimum values. For external thread the maximum material condition occurs when all diameters are at their maximum values and root radius is at its minimum value.

MAXIMUM MATERIAL LIMIT - The maximum limit of size an external dimension or the minimum limit of size of an internal dimension.

MAXIMUM NUT TIGHTENING TORQUE - The maximum amount of torque that can be applied to a nut without causing a failure.

MAXIMUM SCREW TIGHTENING TORQUE - The maximum amount of torque that can be applied to a screw without causing a failure.

MAXIMUM TIGHTENING TORQUE - The maximum amount of torque that can be applied to either a nut or a screw without causing a failure.

MEAN COIL DIAMETER - The mean value of the outside and inside diameters.

MEAN COIL DIAMETER (SPRING TERM) - The average diameter of the spring, equal to half the sum of the inside and outside spring diameters.

MEANSHIFT - The difference in tightening torque values produced by the same tightening tool on hard and soft joints. A hard joint typically gives a high torque value than a soft joint. Generally speaking, the lower the meanshift of a tightening tool, the better it will be in achieving a specified torque value irrespective of the joint conditions.

MEASUREMENT ASSURANCE - Is the technique that may include, but is not limited to: 1) use of good experimental design principles so the entire measurement process, its components, and relevant influence factors can be well characterized, monitored and controlled; 2) complete experimental characterization of the measurement process uncertainty including statistical variations, contributions from all known or suspected influence factors, imported uncertainties, and the propagation of uncertainties throughout the measurement process; and 3) continuously monitoring the performance and state of statistical control of the measurement process with proven statistical process control techniques including the measurement of well characterized check standards along with the normal workload and the use of appropriate control charts.

MEASURING AND TEST EQUIPMENT - Includes all of the measuring instruments, measurement standards, reference materials, and auxiliary apparatus that are necessary to perform a measurement. This term includes measuring equipment used in the course of testing and inspection, as well as that used in calibration.

MECHANICAL PLATING - Dull gray with a smooth finish. Corrosion protection depends on coating thickness. Good coverage in recesses and thread roots. Mechanical plating reduces the risk of hydrogen embrittlement forming with the fasteners. Minimizes the need for the precautionary practice of baking the fasteners soon after plating. This plating process is common for lockwashers made from spring steel to be plated this way to avoid brittleness after baking.

MECHANICAL PRESS - A forging press with an inertia flywheel, a crank and clutch, or other mechanical device to operate the ram.

MECHANICAL PROPERTIES - Properties of a material that reveal the reaction when force is applied, or that involve the relationship between stress and strain, such as modulus of elasticity, tensile strength, and fatigue limit. Rarely are the mechanical properties of the fastener those of the raw material from which it was made. Properties such as tensile and yield strengths, hardness and ductility will vary widely, depending upon choice of manufacturing methods and metallurgical treatments. The term 'mechanical properties' is preferred to 'physical properties'.

MECHANICAL PROPERTIES - Most fastener applications are designed to support or transmit some form of externally applied load. More than 90% of all fasteners are made of carbon steel. In general, taking into account the prices for raw materials, non-ferrous ones should be considered only when a special application is required.

MECHANICAL SCREW MACHINES - These machines consist of eight or more simultaneously operating spindles, metal bar stock attached to the spindles' spring collets, a main drive shaft, a bed lead work shaft, two front cam shafts, a motor and controls. The main drive shaft controls the front two cam shafts and powers the bed lead work shaft. Meanwhile, the motor, which is found at the machine's base, provides power to all operations. Its horsepower varies per the size and speed of the machine it powers and the stock the machine forms. Traditional screw machines are less expensive on the outset and can produce high volumes of product and are not inherently slower than their CNC-operated counterparts. So, in some settings, they work incredibly well.

MECHANICAL TESTING - Testing to determine material strength and other important properties through wedge and axial tensile testing, torque testing, proof load, yield strength and elongation, clamp load analysis, shear testing (single and double), stress rupture, creep, compression, tension fatigue and more

MECHANICAL UPSETTER - A three-element forging press, with two gripper dies and a forming tool, for flanging or forming relatively deep recesses.

MECHANICALLY GALVANIZED - A part coated with a layer of zinc by means of mechanical impact. The thickest levels of mechanical galvanizing (ASTM B695, Class 55 or greater) are considered to be alternatives to hot-dip galvanizing and provide a medium level of corrosion resistance.

MECHANICALLY GALVANIZED - Describes a coating technique of applying cold zinc powder to bolts by either cold welding or barrel finishing. Parts are tumbled in zinc powder, and the peening action of the tumbling embeds powdered zinc into the surface of the part. This creates a thicker and somewhat irregular coating compared to electroplating. Parts must be sized appropriately to allow for the thickness of the coating.

MECHANICALLY LOCKED STEM - The stem or mandrel is locked in the fastener shell during placement via a mechanical system. This eliminates the risk of the stem vibrating loose from the fastener head and the problems associated with loose stems.

MEDIUM CARBON STEEL - Steels containing 0.30% - 0.60% carbon; have sufficient carbon content to yield a consistent heat treatment response. Possess good ductility, strength, and wear resistance; used for large parts, forging and automotive components.

METAL BUSHINGS - A cylindrical hole lining or casing designed to reduce vibrational friction and wear.

METAL HIT ANCHOR - The metal hit anchor or hammer drive anchor is a die-cast anchor consisting of a cylindrical zinc alloy body and zinc plated steel pin expander. The body is split for a major portion at the opposite end the pin expander is inserted. The anchor body is hollow for the entire length to allow space for the pin expander. The pin expander is made of het traded, high carbon steel that is zinc plated.

METAL PRESSING - The act of using a hydraulic, pneumatic, or mechanical power press to cut, form, or assemble metal parts and components.

METAL SPRAYING - The application of a metal layer by a process pf s[raying molten metal from a gun on any brass material

METAL THINNING - Thickness reduction during any forming operation

METALIZING - The application of a metallic layer to the surface of non-metallic materials.

METALLIC STAMPINGS - The final components produced by the action of a press operation, or series of operations, on a metal workpiece.

METALLURGICAL TESTING - Testing to examine microstructure, grain size and grain flow, hardness and microhardness, case depth, plating thickness, thread examination, contamination, surface discontinuities, carburization and decarburization, folds, inter-granular oxidation (IGO),hydrogen embrittlement, alpha case and more

METALLURGY - The science and technology of metals and alloys. Process metallurgy is concerned with the extraction of metals from their ores and with refining of metals; physical metallurgy, with the physical and mechanical properties of metals as affected by composition, processing, and environmental conditions; and mechanical metallurgy, with the response of metals to applied forces.

METRIC DESIGNATION - The letter "M" that is at the beginning of all metric thread designations.

METRIC THREAD STANDARD - A thread made to a scale that is based on millimeters.

MICRO EXAMINATION - Inspection per SAE AS 7477/SSAE AS 7478 includes examinations of flow lines, internal defects, microstructure, grain size per ASTM E11, surface hardening and thread defects.

MICRO INDICATION VERIFICATDION EXAM - The Micro Indication Verification Examination (MIVE) verifies defects found in NDT methods which cannot be fully measured by the NDT method. The MIVE will provide 3-dimensional measurements of indications such as thread laps and seams and can change the disposition of an NDT test from failure to passing if the indications are within the tolerances of the specification.

MICROALLOYED-STEEL FORGING - One made from a microalloyed steel requiring only controlled cooling to reach optimum properties, in contrast to conventional quenched-and-tempered steels that require traditional heat treatment to achieve the same results.

MICROHARDNESS TESTING - Microhardness test a material's hardness in a similar way to Rockwell, but with a microscopic indentation. This test can provide a hardness value for a very precise location on a part, enabling the detection of variations in hardness from one location to another. All tests offer different load options and many different scales between the three testing options.

MICROSTRUCTURE - The structure and internal condition of metals as revealed on a ground and polished (and sometimes etched) surface when observed at high magnification (over 10 diameters).

MIL-STD - 'Military Standard' and for all fastener drawings are prefixed by MS. MIL-Specs used by the Department of Defense.

MIL. - One thousandth of an inch, 0.001 in.

MILL SCALE - The heavy oxide layer that forms during heating and forging of steel.

MILLING - CNC milling is a process that employs rotating, multi-point cutting tools to remove material from a workpiece.

MILLING - Metal removal using a milling machine.

MILLING PROCESS - A machining process whereby a surface is generated with a rotating toothed cutter. Each tooth takes an individual chip.

MINIATURE SCREW - A screw less than 0.06 inches in diameter, having a slotted head, and threaded for assembly with a preformed internal thread.

MINIMUM DISTANCE - The minimum distance from the center of a fastener mounting hole to the nearest edge of a panel, which will keep the edge from deforming. Suitable fixturing and increasing thickness of panel material may reduce the distance.

MINIMUM EDGE DISTANCE - The minimum distance to not spall the concrete when anchor is expanded.

MINIMUM EMBEDMENT - The minimum distance that an anchor should be placed in the base material to achieve holding values.

MINIMUM GRIP - The smallest recommended thickness if joint material for a fastener.

MINIMUM GRIP - Minimum panel thickness into which a given blind hreaded insertcan be properly installed. If the panel is thinner than this value there will too much free counterbore and the bulb will form in an uncontrolled manor.

MINIMUM MATERIAL CONDITION - A condition in which the product contains the minimum amount of material allowed by the specified tolerance. For an internal thread the mimimum material condition occurs when all diameters are at their maximum. For an external thread the mimimum material condition occurs when all diameters are at their minimum and the root radus is at a maximum.

MINIMUM SHEET THICKNESS - The thinnest section of a panel, usually measured in thousands of an inch or millimeters, into which a fastener may properly be installed. The same fastener may be installed in panels having any thinckness greater than mimimum.

MINIMUM SPACING - The minimum distance from centerline to centerline for the anchor expansion forces not to overlap; rule of thumb is 10 anchor diameters.

MINOR DIAMETER - On a straight thread, the minor diameter is the diameter of the coaxial cylinder which would pass through the roots of an external thread or the crests of an internal thread.

MISALIGNMENT - Also referred to as "Skew", this ring dimension is the radial variance of a multiple turn retaining.

MISMATCH - The misalignment or error in register of a pair of forging dies; also applied to the condition of the resulting forging.

MISMATCH ALLOWANCE - An allowance for misalignment (or mismatch) included in forging tolerances.

MISTAKE-PROOFING - A manufacturing technique for providing a signal when an error is about to be introduced into the production process. this can be as simple as the use of a checklist.

MODEL - Pre-production sample made wit limited emphasis on tolerance to test a design concept. In other words a Prototype.

MODEL ENGINEERS THREAD (M.E.) - A thread based upon the Whitworth thread form that was established in 1912. A very fine thread (a 3/32 inch thread having 60tpi for example).

MODIFIED TKO - A special TKO stroke where the tool side kickout stroke starts some distance after front dead center.

MODULUS IN TENSION OR BENDING (SPRING TERM) - Young's Modulus, the coefficient of stiffness used for torsion and flat springs.

MODULUS OF ELASTICITY (E) - A measure of the rigidity of a material. Coefficient of stiffness used for torsion and flat springs; the ratio of stress over strain.

MODULUS OF RIGIDITY - Coefficient of stiffness for extension and compression springs; the modulus in shear.

MODULUS OF RIGIDITY (SPRING TERM) - Modulus in Shear or Torsion, the coefficient of stiffness used for extension and compression springs.

MOLYBDENUM DISULFIDE - Moly coating is typically used as a bonded lubricant, and has some corrosion resistance. It is spray coated to a dry film thickness of .4 to .7 mil, and cured in ovens.

MOLYBDENUM DISULPHIDE - A solid lubricant that acts as a high pressure resistance film. Can be used by itself as a dry lubricant as well as in with other solid lubricants and in oils and greases. Used on threads, such lubricants act as a separating film to prevent corrosion formation on the thread surface (even under adverse temperature and environmental conditions) ensuring the release of the threaded connection. Such films can also act as friction stabilizers.

MOLYDBENUM - Also known as Moly. The metal is added to 316 stainless steel to sharply increase its corrosion resistance to chlorides and sulfates and various acids sed in the pulp industry. Moly helps to reduce hardness and increase tensile strength at higher temperatures.

MONEL® - Nickel-Copper alloy. Has excellent corrosion resistance in heat and salt water. Basically two-thirds nickel and one part copper.

MORTORQ - Mortorq developed by Phillips Screw Company is a format, used in automotive and aerospace applications. It is designed to be a lightweight, low-profile and high-strength drive, with full contact over the entire recess wing, reducing risk of stripping.

MOUNTING HOLE - A properly sized, usually round, opening in a panel to accept a fastener. Mounting hole diameter is very critical and must be specific to the fastener that will be installed.

MP35N - The superman of materials, this material defines strength. It is a nickel-cobalt based alloy that boasts ultra-high strength, toughness, and ductility. Maintains strength in maximum operating temperature of 800 degrees F. Tensile strength of 227-294 ksi at room temperature. Resists corrosion in hydrogen sulphide, salt water and other chloride solutions. Resistant to crevice and stress corrosion cracking in extreme environments. Used on space shuttle structure.

Mpa - Mega Pascal. The SI unit of pressure or stress. It is measure of perpendicular force per unit area. One mega Pascal is equal to 1,000,000 Pascals.

MPM - An abbreviation for (Micro Position Monitor). This is a non-contact gross load monitor.

MRP SYSTEM - Acronym for Material Requirements Planning. A type of inventory control system(usually software-based) used to manage and streamline a company's manufacturing processes.

MS - Military Standard. These specs guarantee physical and mechanical quality and are traceable back to the raw material and testing certifications. Recently replaced by NASM specifications but are interchangeable.

MS MILITARY STANDARDS - A United States Defense Standard is used to help achieve standardization objectives by the U.S. Department of Defense.

MUDA (WASTE) - A Japanese term meaning any activity that consumes resources but creates no value. Those activities and results that should be eliminated, many references cite the following seven categories of waste: Excessive or early production, Delays, Most movement and transport, Poor process design, Most inventory

MULTILAYER DEPOSIT - An electrodeposit consisting of two or more layers of metal of different nature or composition deposited successively.

MULTIPLE - (1) Term used to describe a die impression designed to produce more than a single piece at a time (2) A piece of stock for forging tat is cut from bar or billet lengths to provide the exact amount of material needed for a single workpiece.

MULTIPLE LEAD THREAD - Also known as multi-start thread. A thread in which there is more than one helix. For multiple lead threads the helix is always equally spaced, that is a double thread has the two helixes 180 degrees apart whereas a triple lead thread has them 120 degrees apart. Multiple lead threads have a steeper helix than single lead thread of the d=same size and pitch combination.

MULTIPLE SLIDE PRESS - A press that uses two or more synchronized sliding actions to strike and form the workpiece from different directions.

MURA - Inconsistency or variation