McGuire Glossary of Fastener Terminology

D - 169 terms

DACROMET - A high performance surface coasting that can be applied to fasteners. The coating consists of passivated zinc flakes that are stoved onto the metal surface. The coating can be coloured and eliminates the risk of hydrogen embrittlement associated with electroplated metal DACROMET is a registered trademark of Metal Coating International, Inc. f Chardon, Ohio.

DACROTIZED - Dacrotized is a pollution free ceramic coating for screws used with treated lumber. Coating is comparable to the corrosion resistance of hot-dep galvanized fasteners. Plating can typically withstand a 500-hour salt spray test. There is no risk of hydrogen embrittlement with Dacrotized plating.

DATUMS - Theoretically exact planes, lines or points from which other features are located on design drawings.

DEAD COILS - The coils of a spring that do not affect the spring rate

DEBURR - To remove chips, burrs, or other imperfections through a secondary operation such as grinding.

DEBURR - To remove the sharp, knife-like edge from parts.

DEBURRING - The removal of burrs, sharp edges, or fins by mechanical, chemical, or electrochemical means.

DECARBURIZATION - The loss of carbon from the surface of an iron-base alloy as the result of heating in a medium that reacts with the carbon.

DECARBURIZATION - The removal of carbon from the surface of steel as a result of heating in a medium that reacts with the carbon. Decarburization is usually present to a slight extent in steel forgings. Excessive decarburization can result in defective products. Decarburization may also occur through the normal aging process of oxidation.

DECARBURIZED - A fastener has a decarburized surface when the carbon content of the surface is lower than the carbon content of the core. Loss of carbon from the surface layer of a carbon-containing alloy due to reaction with one or more chemical substances in a medium that contacts the surface.

DECOMPRESSION POINT - The point at which there is zero pressure at the joint interface as a result of forces applied to the joint. If the applied force is increased beyond the decompression point, a gap will form at the interface. Analytically, a criteria of joint failure is often taken as when the applied force on the joint reaches the decompression point. This is because forces acting on the bolt(s) can dramatically increase at this point. Loading beyond this point can also result in fretting at the interface that will lead to bolt tension loss that will subsequently lower the decompression point. This process can continue until bolt failure does occur. The failure can be fatigue or other mechanism but the underlying cause was loading of the joint beyond the decompression point. It is for this reason that it is frequently taken as a failure criteria in analysis work.

DEDICATED TOOLING - Commonly referred to as (hard tooling) - is tooling made to produce a specific part.

DEEP DRAW STAMPING - During deep draw stamping operations, a sheet metal blank is pullled into a die via a punch, which forms the sheet metal into the desired shape. The depth of the drawn component must exceed its diameter for the process to be considered a deep draw.

DEEP DRAWING - The process of working metal blanks in dies on a press into shapes which are usually more or less cup like in character.

DEFECT - A defect is any deviation of a unit of product from the requirements of the specifications or standards to which it should be produced. Defects are classified as follows:

• Dud: A dud is an incomplete, mutilated, or foreign part.
• Major Characteristics: A major characteristic is one that could result in failure or materially reduce the usability of the product for its design capability as defined by the application standards and specifications.
• Minor Characteristics A: A minor characteristic A is one that does not materially reduce the usability of the product; and is of a lessor importance than those of established as Major.
• Minor Characteristics B: A minor characteristic B is one that has no great importance to the usability of the product, but one for which standards have been established. Normally the greatest possible latitude in acceptability is given Minor B defects.

DEFLECTION - The degree to which a washer is displaced under load. Belleville Spring washers are designed to produce predictable load versus deflection characteristics. Spring washers can be configured in parallel stacks to increase load or stack in series to increase deflection. The load and deflection can also be adjusted by adding or removing additional washers and/or by changing the sequence in which they are arranged.

DEFLECTION(S) - Relative displacement of the ends of a spring under the application of a force.

DEFORMA - A finite element analysis program for the cold forming process. This is the registered trademark of Scientific Technologies Corporation.

DELONIZATION (DEMINERALIZATION) - The removal of ions from a solution by ion exchange.

DEOXIDIATION - Process of reducing the oxygen content from steel during steel making process by adding strong oxide forming elements, such as aluminum.

DEOXIDIZER - Any item which removes or reduces the amount of oxygen in a part.

DEPOLARIZATION - A decrease in the polarization of an electrode.

DEPTH - The length of the space measured from the base of the root to an imaginary line spanning the crests of a thread

DEPTH OF CUT - Denotes how much material is being removed from a work piece with each pass of the tool.

DESCALING - The process of removing the flaky oxide film known as scale that forms on the surface of the fastener during production. Wire brushes, water spray, scraping equipment, and light blows to the metal are often used.

DESIGN FORM OF THREAD - The design form of an internal or external thread is the thread form in it's maximum metal condition. it is the same as the basic thread profile except that the thread roots are rounded. If either the internal or external thread form exceeds the design form of the thread profile then a potential interference exists.

DESIGN LOAD - The calculated maximum load that is to be applied to the anchor for the life of the structure. This should also be used for fasteners.

DESIGN SEPARATION LOAD - The limit tensile load multiplied by a separation factor of safety.

DESIGN SIZE - The size from which the limits of size are derived by the application of tolerances. When there is no allowance the design size is the same as the basic design.

DESIGN STRENGTH - The nominal strength of an anchor calculated per ACI 318, ICC-ES AC193 or ICC-ES AC308 and then multiplied by a strength reduction factor.

DESTRUCTIVE TEST - A test to determine the mechanical properties of a material or the behavior of an item which results in the destruction of the sample or item.

DETERGENT - A surface-active agent that possesses the ability to assist in cleaning soiled surfaces.

DETRIMENTAL YIELDING - Yielding that adversely affects fit, form, function, or integrity of the structure.

DFSS - An acronym meaning design for six sigma.

DFX - An acronym meaning design for X, where X represents an attribute such as service, assembly or manufacture.

DIAMOND POINT - Most common nail point, comprised of 4 sides and ends in a point

DIAMOND PYRAMID HARDNESS TEST - An indentation hardness test employing a diamond pyramid indenter and variable loads enabling the use of hardness scale for all ranges of hardness from soft lead to tungsten carbide.

DIAMOND TIP BIT - The diamond grit is embedded in the steel substance and improves screw engagement reducing the risk of damage to the screw recess. This extra hard diamond coating wears less and grips better than a Titanium coating.

DIAPHRAGM (IN ELECTROPLATING) - A porous separator dividing anode and cathode compartments of an electroplating tank from each other or from an intermediate compartment.

DICHROMATE - In the early days of the plating industry, sodium dichromate, a solid, was used in the manufacture of the yellow chromate conversion coating baths. In modern times, no dichromate is used by platers, but the term "dichromate" is still widely used to describe the yellow zinc plating process. All chromate conversion coatings are true chromates and do not contain dichromate.

DICHROMATE - A secondary dipping in various colors such as yellow, brown, green or iridescent after plating increasing corrosion resistance and color finish.

DIE - (1) One of a pair of hardened metal blocks for forming, impressing, or cutting out a desired shape. (2) A tool for cutting external threads. Opposite of tap.

DIE - Tool with a void or cavity which is precisely fitted to a (PUNCH) used to shear or form sheet metal parts.

DIE - An individual tooling component with a forging cavity or the assembly of a case, inserts, fillers, etc. on the stationary side of the tooling

DIE BLOCK - The holder for the stationary side tooling. Can hold from one to six dies depending on the machine type. Metal blocks with impressions of the desired shape of a metal used during the open and closed-die forging.

DIE CASTING - A very accurate and smooth casting made by pouring a molten alloy usually under pressure into metal mold or die. Zinc Die Casted Fasteners.

DIE CHASER - The separate cutting tools used in die heads which actually cut the screw threads.

DIE CLEARANCE - Amount of space between the punch and die opening.

DIE CUSHION - An accessory that provides an opposing motion or counterforce to aid in the forming and release of the workpiece. Die cushions are typically pneumatic, but they may also be comprised of hydraulic systems, rubber, and springs. They may also be used for several operations including blank holding, uniform pressure regulations, knockout, et.

DIE HEIGHT - The distance measured from the bottom face of the ram or slide to the top of the bolster when the slide is positioned at the bottom of its stroke (bottom dead center/BDC).

DIE HOLDER - Also known as bolster, insert holder, can. Used to locate, clamp and support dies, die assemblies or die inserts.

DIE IMPRESSION - The portion of the die surface that shapes the forging.

DIE LIFE - The duration of a die impression or die block measured by how many forgings it has produced before it becomes too worn to use.

DIE LUBRICANT - A material sprayed, swabbed, or otherwise applied during forging to reduce friction and/or provide thermal insulation between the workpiece and the dies. Lubricants also facilitate release of the part from the dies and provide thermal insulation.

DIE LUBRICATION - The recirculating liquid lubrication applied to the tooling or workpiece during the forming operations. It reduces friction, minimizes tooling wear, lubricates the tooling, and helps to carry away the heat generated by the cold forming process.

DIE MARKS - Scratches, scrub marks, indentations, galling or burnishing of sheet metal workpieces by tooling.

DIE MATCH - Also known as mismatch. The alignment of the upper (moving) and lower (stationary) impression in the die.

DIE POINT - One of the least expensive pointing operations applied at the time of heading. This operation provides an end chamfer starting with a diameter smaller than the root diameter of the thread. The minimum reduction of the point is approximately 10% below the maximum minor diameter with an included angle of 40 to 50 degrees

DIE POINT - A forward extrusion that is stopped on the end of a shank forming a chamfer. See POINTING.

DIE PROOF (CAST) - A casting of the die impression made to confirm the exactness of the impression.

DIE PROTECTION - A system of protective measures, including proximately sensors, used to monitor the operation of the tooling, reducing the risk of heavy impacts and crashes due to equipment malfunction.

DIE RATIO - The ratio between the outside diameter of the case and the inside diameter of the insert.

DIE RETAINER - This device is used to hold the die case assembly in the die block on FORMAX or FORMAX Plus machines.

DIE SET - The assembly of the upper and lower die shoes (punch and die holders), usually including the guide pins, guide pin bushings, and heel blocks. This assembly takes many forms, shapes, and sizes and is frequently purchased as a commercially available unit. Also, two (or, for a mechanical upsetter, three) machined dies used together during the production of a die forging.

DIE SHIFT - The condition that occurs after the dies have been set up in a forging unit in which a portion of the impression of one die is not in perfect alignment with the corresponding portion of the other die. This results in a mismatch in the forging, a condition that must be held with in the specified tolerance.

DIE SHOES - The upper and lower plates of castings that constitute a die set (punch and die holder). Also a plated or block upon which a die holder is mounted, functioning primarily as a base for the complete die assembly. This plate or block is bolted or clamped to the bolster plate or the face of the press ram.

DIE SIDE INSTALLATION - The installation of a fastener into the die side of a punched mounting hole in a panel. The die side of a hole usually exhibits blow out and is larger in size than the punch side of the hole.

DIE SINKING - The process of machining impressions in die blocks.

DIE SLIDE - The linear distance a sliding die must move to allow for the backward extrusion of a hole, piercing , or the upsetting of a preform.

DIE SPACE - A drawing or series of drawings showing the dimensions in the tooling area that must be used during the tooling design.

DIE STRAIGHTEN - A straightening operation performed in either a hammer or press using flat or cavity dies to remove undesired deformation and bring the forging with the straightness tolerance.

DIEPAK - The die side assembly of the Formapak on FORMAX & FORMAX Plus machines. It includes the die block and faceplate.

DIES (DIE BLOCKS) - The metal blocks into which forging impressions are machined and from which forgings are produced.

DIES, FORGING - Forms for the making of forgings; generally consist of a top and bottom die. The simplest will form a completed forging in a single impression; the most complex, made up of several die inserts, may have a numbers of impressions for the progressive working of complicated shapes. Forging dies are usually of blocks and the balance of the impression in the other block.

DIES, GRIPPER - Clamping or lateral dies used in a forging machine or mechanical upsetter.

DIFFERENTIAL THERMAL EXPANSION (DTE) - DTE is experienced when connecting materials expand or contract at different rates during a change in temperature and impact the performance of the joint integrity.

DIFFUSION - The moment of atoms on one material into the crystal lattice of an adjoining material

DIFFUSION TREATMENT - Process introduced by diffusion of any metal or non-metal into the surface layer.

DIGITAL IMAGING - The technicians record digital images of all indications found in NDT, and all metallographic tests.

DIGITIZER - Scans and maps the surface of a real object, producing a 3D computer model for CAD/CAM programs.

DILATOMETER - An instrument for measuring the linear expansion or contraction in a metal resulting from changes in such factors as temperature and allotropy.

DILATOMETER - An instrument for measuring the linear expansion or contraction in a metal resulting from changes in such factors as temperature and allotropy

DIMENSION - Numerical values expressed in units of measure that are indicated on a drawing along with lines, symbols, and notes to define the characteristics of a fastener.

DIMPLE - A conical or domed impression on the end of a formed part often used as a preform for a subsequent forming or extruding operation.

DIMPLE - The cone shaped indentatioin which is applied to the point end of type FH and HFH studs and to the head end of typeTFH studs. The dimple is a registered trademark and is used to tell PEM(R) studs from studs manufacturered by competitors.

DIMPLING - Term used to describe the act of applying the thread lock to SI inserts.

DIN - An abbreviation for Deutsches Institut fur Normung, the German standards body. In reference to fasteners DIN indicates fasteners that conform to the dimensional and mechanical properties of metric fasteners. Specific metric standards (will be followed by the standard number for example DIN 932).

DIP AND DRAIN - In the conventional dip drian coating process, the parts to be coated are immersed in the paint and them removed at a controlled speed. The dip drain coating process uses both solvent-based and water-based dip coatings. The advantage of this process is the high degree of automation and the complete painting of the components with minimal loss of coating material - no overspray.

DIP SPIN - The coating of small parts (i.e.bulk material) often takes place in a dip-spin process. In this process. the coating is applied to the parts in a basket or a barrel. The basket is then immerersed in a dip tank where the paint wets the entire surface of the parts. While immersed in the coating, the basket is slowly rotated which assists in te elimination of air-pockets and improves coverage. After the dipping process, the basket is removed from the dip-tank and rotated or centifuged, so that the coated parts are thrown against the outer wall of the basket. Excess coating is removed from the parts due to the centrifugal force and escapaes throufh small holes in the basket back into the dip tank.

DIPHASE CLEANING - Cleaning by means of a liquid system that consists of an organic solvent layer and an aqueous layer. Cleaning is effected both both solvent and emulsifying action.

DIRECTIONAL BENDING - Fracture marks left on the surface from a fastener failure (breakage).

DIRECTIONAL PROPERTIES - Properties whose magnitude varies depending on the relation of the test axis to a specific direction within the metal or alloy.

DISC (DISK) - Pancake shaped forging (flat with a round cross-section); e.g. a blank for gears, rings and flanged hubs. Abbreviation is D.

DISCONTINUITIES - Small or large disfigurations in a fastener such as pits, tool marks, voids, laps, folds etc. Minor discontinuities are typically allowed, major as defined by carious military specifications AN, MS, NAS and NASM.

DISCONTINUITIES - Includes cracks, laps, folds, cold shuts, and flow-through, as well as internal defects such as inclusion, segregation, and porosity; internal discontinuities can be detected and evaluated using ultrasonic testing equipment.

DISH - This ring dimension is the height difference in the ring cross section's axis of symmetry between O.D. and I.D.

DISPLACE - The movement of metal from one place to another, a combination of extruding and upsetting.

DISPLACER - The portion of a self-clinching fastener that moves or displaces, the panel material. Usually the head, lugs, or knurled portion of the fastener. It could be a cylinder, a knurl, or a hex.

DISPLACER - The portion of a self-clinching fastener that moves, or displaces, the panel material. Usually the head, lugs or knurled portion of the fastener. It could be a cylinder, a knurl, or a hex.

DISTRIBUTOR BLOCK - The component of the press lubrication system used to dispense oil/grease to the relevant areas of the equipment.

DMAIC - The core problem solving methodology used by many lean six sigma companies. The term refers to the steps: define, measure, analyze, improve and control.

DOG POINT - A cylindrical extension, or pilot, of diameter smaller than the minor diameter of the thread, commonly equal to about D/2 in length, with a conical section between it and the thread; usually used as a pilot in assembling or as the end of a set screw projecting into a fairly deep hole or clot. On small screws the dog point is usually extending in length about two-thirds the diameter of the thread. Recommended for ease in starting to insure against stripping fine threaded products, and to increase efficiency along production lines.

DOMED HEAD - Type of fastener head having a rounded, or semispherical, upper surface. Common on some types of Plow Bolts.

DOUBLE EXPANSION ANCHOR - The double expansion anchor is made up of five parts: a cone shaped expander nut, a hollow cone, outer body and two spring bands. The spring bands hold all the anchor parts together into one preassembled single piece and are made from zinc-plated steel. The hollow cone and cone nut are the same except that the cone nut has internal threads and are made from Zamak material. The out body is tubular and made from die-cast zinc alloy Zamak.

DOUBLE FORGING - A forging designed to be cut apart and used as two separate pieces.

DOUBLE HEADER - A situation where two parts have been accidentally formed in a die.

DOUBLE HEX - Double Hex is a socket recess with two coaxial offset hex recesses; it can be driven by standard hex key tools.

DOUBLE KNURLING - A defective condition which occurs when a knurl does not track properly and produces twice as many teeth per inch on the work as were present on the knurling wheel.

DOUBLE PUNCH OUT - Refers to a hollow part that has been pierced, then upset forming a second slug, and pierced a second time.

DOUBLE SALT - Two salts tat crystallise together in stoichiometric proportions but give there actions of the ions of the constituent single salts in aqueous solution. Example: Rochelle Salt.

DOUBLE TEMPERING - A treatment in which quench-hardened steel is given two complete tempering cycles at substantially the same temperature for the purpose of ensuring completion of the tempering reaction and promoting stability of the resulting microstructure.

DOUBLE TRIM - (1) A forming sequence where the formed part is trimmed twice. Such as in the forming of a hex flange bolt. The hex is sheared out of a preform shape and the flange is formed in one operation and then the flange diameter is sheared to size in the next forming operation. (2) A trimming technique using two opposing trim dies to reduce the amount of burr below a trimmed surface.

DOUBLE UPSET - The forming of a second upset on a part on the opposite end from the first upset. Requires the use of a special opening segment tooling.

DOUBLE-SQUARE - The Double-Square drive is two squares superimposed at 45 degree rotation, forming an 8 pointed star. The design is similar to a square drive (Robertson), but can be engaged at more frequent angles by the driver bit.

DOUBLE-START THREAD - Having two ridges wrapped around the cylinder

DPMO - An acronym meaning defects per million opportunities.

DPQ - An acronym meaning defects per opportunity.

DPU - A term meaning defects per unit.

DRAFT - The necessary taper on the side of a forging to allow removal from the dies; also applies to the die impression. Commonly expressed in degrees as the draft angle. As applied to open die forging, draft is the amount of relative movement of the dies toward each other through the metal in one application of power.

DRAFT ANGLE - The angle of taper, expressed in degrees (usually 5 to 7 degrees), given to the sides of the forging and the side walls of the die impression.

DRAFTLESS FORGING - A forging with zero draft on vertical walls.

DRAG-IN - The liquid carried into a bath y the objects introduced therein.

DRAG-OUT - The liquid carried out of a bath by the objects removed from there.

DRAW BOLT - A special contoured bolt and sleeve combination used to clamp a punch in a tool holder. Also used to hold in either the cutter or quill on FORMAX, FORMAX Plus and Large FORMAX Plus machines.

DRAW DIE - A tooling component located in a wire drawer It slightly reduces the diameter of the incoming wire and helps to press lubricant onto the surface of the wire. Also see DRAWING & WIRE DRAWER.

DRAWING - Drawing may refer to the pulling of steel through a die, as in drawing wire, or deforming steel in dies on a press (deep drawing).

DRAWING - (1) Engineering document depicting a part or assembly. (2) In metal forming, the stretching or compressing of a sheet metal part into a die by a punch to create a 3-dimensional part.

DRAWING - (1) A forging operation in which the cross section of forging stock is reduced and the stock lengthened between flat or simple contour dies. (2) In heat treating, the same as tempering.

DRAWING - (1) A metal forming operation done on a cup type part. The part is pushed through series of progressively smaller diameter dies with an mandrel. The thickness of the wall is reduced resulting in a longer part. (2) The process used to reduce the diameter of the incoming wire by passing it through an insert before entering the machine. See DRAW Die.

DRAWING - Primarily used in the creation of electronic components, drawing is a process that uses tensile force to shape the component into a desired thickness and shape. During the drawing process, blanks are drawn over a die, slowly stretching them and manipulating them into a new structure.

DRAWING (TEMPERING) - Metal is reheated after being hardened, then held at a specific temperature, and finally quenched. This reduces hardness and increases toughness

DRAWING OUT - The forging operation in which the length of a metal mass (stock) is increased at the expense of its cross section; no upset is involved. The operation covers converting ingot to pressed bar using (V) , round or flat dies.

DRESSOUT - A condition where the dimensions of a part or forging are changed by local grinding or machining to remove one or more defects thereby causing a localized imperfection of a maximum depth. The depth is the dimension of the dressout.

DRIFTING - In forging, the operation of forming or enlarging a hole by use of a tapered punch.

DRILED SHANK - A fastener shank with a hole drilled through it for a pin (i.e. cotter pin) or safety wire.

DRILL - (v) To sink a hole with a drill, usually a twist drill. (n) A pointed cutting tool rotated under pressure.

DRILL FLUTES - Allow drilled material to exit the hole. Completely embedded flutes can no longer remove these chips, which contain approximately 80% of the heat created by drilling process. A buildup of this material can cause the point on a self-drilling screw to over heat and fail.

DRILLED HEAD - A fastener head with a hole drilled through it for a safety wire.

DRILLING - The process of forming holes by means of specialized cutting tools called drills.

DRIVE SCREW - The male threaded part in the nose of a threaded insert-installation tool, which engages the female thread of inserts.

DRIVE TORQUE - Maximum torque to install a screw prior to contact of the head of the fastener with surface of the test plate.

DRIVE TYPE - SET SCREWS - Most set screws use socket (either hex or fluted) drive or a slot drive. The type of drive affects the seating torque that can be attained because it determines how much torque can be transmitted to the screw. Less torque can be transmitted through a slot drive than a socket drive. Therefore, holding power of the slotted screw is about 45% less.

DRIVER ADAPTER - A torque sensor that connects to a computer interface. A driver adapter is a device that expands the range of the tool.

DRIVER HEAD - A head, on a bolt or screw, designed for driving the fastener by means of a tool other than a wrench, such as a screwdriver.

DROP FORGING - Forming metal, usually under impact, by compression within dies designed to produce the required shape.

DROP FORGING - A forging made in closed or impression dies under a drop or steam hammer.

DROP HAMMER - A term generally applied to forging hammers wherein energy for forging is provided by gravity, steam, or compressed air.

DROP OUT/REFEED - A cold forming technique used with difficult to form materials, The part is formed in several stations and then dropped from the machine, The partially formed part can then be annealed and coated or heated and the re-fed into the machine for finish forming operations, Requires many machine specials and secondary equipment.

DROP-IN ANCHOR - A post-installed mechanical anchor consisting of an internally-threaded steel shell and a tapered expander plug. The bottom end of the steel shell is slotted longitudinally into equal segments. The anchor is installed in a pre-drilled hole using a hammer and a hand-setting tool. The anchor is set when the tapered expander plug is driven toward the bottom end of the anchor such that the shoulder of the hand-setting tool makes contact with the top end of the anchor. A drop-in anchor may also be referred to as a displacement controlled expansion anchor.

DRUNKENNESS - An old term which has now been replaced by the politically correct term helix variation

DTI WASHER - Direct Tension Indicating Washer; aka Load Indicating Washer. A washer that has raised bumps which plastically deform to become flat under a specific tensile load.

DUAL TRANSFER - A special design transfer for large Cold Formers. With one transfer slide installed, it moves like a normal straight across transfer. With the combination slide installed, it moves similar to a FORMAXPLUS PMP Transfer. The fingers lift from the face of the dies, the slide moves to the delivery station, and the transfer delivers the part into the next die. This combination transfer slide also as the ability to rotate parts 180 degrees between forming stations, but with very limited finger opening.

DUCTILE - Material propertly, usually describing metal, which is not brittle and can be easly formed or bent. Clinching works in ductile material onlky.

DUCTILE ANCHOR SYSTEM - The behavior of an anchor system where a ductile steel insert governs the design over concrete breakout, pullout, and adhesive bond.

DUCTILITY - The ability to permit change of shape without fracture. In steel, ductility is usually measured be elongation and reduction of area as determined in a tensile test. The lower the ration of its specified minimum yield strength to its specified minimum tensile strength, the grater the fastener's ductility.

DUCTILITY - Ability of a material to be bent or otherwise formed without fracture.

DUCTILITY - The property of a metal that enables it to stretch before rupturing.

DUCTILITY - A material under tensile stress with an elongation of at least 14% and an area reduction of at least 30% prior to rupture.

DULL FINISH - A finish virtually lacking both diffuse and specular reflecance.

DULL NICKEL - Whitish cast can be obtained by mechanical surface plating or a special satin bath.

DUMMY (OR DUMMY CATHODE) - A cathode used for removal decomposition of impurities from electroplating solutions.

DUPLEX (NAIL) - A common nail with a second head, allowing for the easy extraction; often used for temporary work, such as concrete forms or wood scaffolding; sometimes called a "scaffold nail."

DUPLEX RIVET - A two-piece rivet designed for easy upsetting and hole filling properties.

DWELL - Portion of a press cycle during which the movement of a member is zero or at least insignificant. Usually refers to the interval between the completion of the forging stroke and the retraction of the ram.

DYE-PENETRANT TESTING - Inspection procedures for detecting surface irregularities using penetrating liquids containing dyes or fluorescent substances.

DYEING (IN ELECTROPLATING) - Imparting a colour by the use of organic dyestuffs.

DYNAMIC FRICTION - Resistance to relative movement of two bodies that are already in motion.

DYNAMIC FRICTION - Resistance to relative movement of two bodies that are already in motion.

DYNAMIC LOAD - A load whose magnitude varies with time.