McGuire Glossary of Fastener Terminology

S - 332 terms

SLIP-CRITICAL JOINT - A joint that resists shear loads by faying surface friction. If slip occurs, the integrity of the joint could be compromised. Considered a Friction-type joint

SACRIFICIAL PROTECTION - A form of corrosion protection, wherein one metal corrodes in preference to another, thereby protecting the latter from corrosion.

SACRIFICIAL PROTECTION - The form of cathodic corrosion protection where in one metal corrodes in preference to another, thereby protecting the latter from corrosion (also see anodic coating)

SADDEN - To forge an ingot lightly in the initial forging operation in order to break up and refine coarse, as-cast structure at the surface.

SAE - Specification standards developed by the Society of Automotive Engineers, Inc from which many screw thread standards conforming to United and American Standards are derived.

SAFETY FACTOR (K) - Mathematical constant used in many design formulas to account for theoretical inaccuracies.

SALINE - A solution containing salt. The presence of a saline solution creates a highly corrosive environment for metal since it will act as an electrolyte (e.g. saltwater).

SALT BATH HEAT TREATMENT - Heat treatment carried out in a bath of molten salt.

SALT BATH HEAT TREATMENT - Heat treatment carried out in a bath of molten salt.

SALT FOG CHAMBER - Tests to determine how fasteners will stand up to the elements. Tests include salt spray/salt fog testing, humidity testing high and low temperature testing, chemical exposure testing, and other environmental custom type testing

SAMPLE - A sample is one or more units of product drawn from a lot; the units being selected at random without regard to their quality.

SAMPLE SIZE - The sample size is the number of units in the sample, sample size is determined by the lot size.

SAND BLASTING - Abrasive blasting with sand or related hard material of similar particle size.

SATIN FINISH - A surface finish that behaves as a diffuse reflector and which is lustrous but not mirror-like.

SCALE - An oxide of iron sometimes formed on the surfaces of hot headed or forged fasteners.

SCALE - An adherent oxide coating that is thicker than the superficial film referred to as tarnish.

SCATTER (Torque) - This term refers to the relative inaccuracy of using torque to preload a joint. For a given target preload, a variety of torque values can be empirically derived that will achieve this preload. The reason is the variations in surface roughness and geometric differences between manufactured parts means different torque values (scatter) can provide the same amount of preload in a joint.

SCRAP - (1) Rejected Parts (2) Pierced out slug or trim ring.

SCRAP - Leftover, unused material relegated to recycling.

SCREW - An externally threaded fastener. Screw can be assembled by the head or with a nut. A headed threaded fastener that is designed to be used in conjunction with a pre formed internal thread or alternatively forming its own thread. Historically, it was a threaded fastener with the thread running up to the head of the fastener that has no plain shank. However, this definition has largely been superseded to avoid confusion over the difference between a bolt and a screw.

SCREW ANCHOR - A post-installed anchor that is a threaded mechanical fastener placed in a pre-drilled hole. The anchor derives its tensile strength from the mechanical interlock of the fastener threads with the grooves cut into the concrete during the anchor installation.

SCREW CAP - Retention method that allows the bit to be inserted into the screw cap which is then threaded onto the bit holder.

SCREW HANDEDNESS - Refers to the direction that a screw's thread wraps around its shank.

SCREW MACHINE - A screw machine is a lathe that creates parts from a continuously fed bar stock.

SCREW SHANK - Spiral thread on the shank causes screw shank nails to turn into wood; increases holding and withdrawal capacity in hard woods; scw shank nails can splinter soft wood.

SCREW SHEAR AREA - Cross sectional area of the screw that would need to shear, for a screw stripping failure to result.

SCREW STOCK - Metal in the form of wire or rod which is used for making screws machine parts. Usually it is of a free machining type of material.

SCREW THREAD - A ridge of constant section which is manufactured so that a helix is developed on the internal or external surface of a cylinder.

SCREW THREAD CHASERS - Cutting tools having teeth spaced to match the pitch of the threads to be cut.

SEALED HEAD - A term used to describe any style of insert that has had a ring or elastomer applied at the intersection of the head and shank. This could be a neoprene bonded washer, O-ring, or a sealing compound.

SEALING OF ANODIC COATING - A process which, by absorption, chemical reaction, or other mechanism, increases the resistance of anodic coating to staining and corrosion, improves the durability of colors produced in the coating, or imparts other desirable properties.

SEAM - A longitudinal surface defect in a wire product.

SEAM - A linear flaw on the outside surface of wire. It can lead to cracking of the material when upset.

SEATING TORQUE - On set screws, the torsional holding power is almost directly proportional to the seating torque of cup, flat, and oval-point setscrews.

SEATING TORQUE - Sometimes referred to as "Loading Torque". Typically measured in "inch pounds", a value of torque applied to a fastener to induce a compressive load under the head bearing surface. Results in creating an axial load (pre-load) that imparts tension or a stretching/elongation characteristic to a part.

SEATING TORQUE - Seating Torque (Loading Torque, Tightening Torque) A value of torque typically measured in "Inch-pounds" applied to a fastener induce a compressive load under the head bearing surface that results in creating an axial load (pre-load) NYLOK

SEATING TORQUE (LOADING OR TIGHTENING TORQUE) - A value of torque typically measured in "inch-pounds" applied to a fastener to induce a compressive load under the head bearing surface that results in creating an axial load (pre-load).

SECOND GRIP - For a given type and thread size, the part with the second lowest value of grip range is commonly referred to as a second grip part. The next grip range is a third grip part and so on. For some thread sizes of thick wall parts, the catalog lists six grip ranges, in which case the highest grip range part would be referred to as a sixth grip part.

SECONDARY LOOPING & BENDING - Cold work process done in the secondary department or on CNC machinery.

SECONDARY OPERATIONS - Less important than the major steps of heading or cold forming fasteners, secondary operations include grinding, drilling, polishing, nylon patching and the like.

SECURITY FASTENERS - Includes nuts, bolts and screws and are often called tamperproof or tamper-resistant fasteners. There is a wide variety of drive recesses to select from for a wide variety of applications. All are made as anti-theft and anti-vandalism fasteners and designed to be difficult to remove. Fasteners are available in steel and stainless steel.

SECURITY HEX DRIVE - A Security Hex screw drive features an extruded pin to make the fastener more tamper resistant by inserting a pin in the fastener screw drive recess, requiring a tool with a corresponding hole to drive the fastener. This can also prevent attempts to turn the screw with a small flat bladed screwdriver.

SECURITY TORX DRIVE - A Security Torx screw driver is a common modification to socket and cruciform style drives to make the fastener more tamper-resistant by inserting a pin in the fastener screw drive recess, requiring a tool with a corresponding hole to drive the fastener. See Security Hex Drive

SEGMENTED INSERTS - (1) An insert made form more than one piece. An example would be a hex insert made from six pieces and assembled into a sleeve. This is done to improve the life of the insert. (2) A special insert design used for double upsetting. The insert is split into three or four pieces so that it can open and close to allow for the kickout of the finished part.

SEGREGATION - The distribution of alloying elements in a metal that are non-uniformed. This occurs during shape casting or solidification.

SEIBAN - Seiban is the name of a Japanese management practice from the Japanese words "sei" which means manufacturing, and "ban" which means number. A Seiban number is assigned to all parts, materials, and purchase orders associated with a particular customer's job or project. This enables a manufacturer to track progress.

SELF-CLINCHING - The method by which a fastener is securely attached to a sheet of ductile material by causing the material to cold flow under pressure into an annular recess of the fastener thereby securely locking it in place.

SELF-EXPANDING, CRUSH CLINCH - A fastener with a shank or barrel which is compressed during installation to hold it in place and flush from the opposite side of the panel.

SELF-LOCKING - A locking element formed is an integral part of a fastener, which provides force to restrict the rotational movement of a threaded member.

SELF-LOOSENING - Threaded fasteners can come loose on occasions without human intervention. This loosening can be due to creep, embedding, stress relaxation or the fastener self-rotating (which is often called vibration loosening). Creep, embedding and stress relaxation will generally not completely loosen a fastener, these loosening mechanisms occur without the nut rotating relative to the bolt. The term self-loosening is sometimes used for the nut rotating relative to the bolt without human intervention. It is now that the fastener can self-rotate under the action of transverse joint movement that can completely loosen a tightened fastener such that the nut will become detached from the bolt.

SEMI-FINISHED FASTENER - A fastener made to the same basic dimensions as a finished fastener but having greater tolerances on most dimensions and only the bearing surface and threads finished.

SEMI-TUBULAR RIVET - A rivet with a cavity extending less than half the length of the shank.

SEMI-UNIVERSAL UNIT - A transfer unit for the Universal Transfer or UTII transfer that allowed the use of CNF spring style, non-opening transfer fingers.

SEMS - A preassembled screw and washer unite in which the washer is retained free to rotate under the screw head by the rolled thread. These units expedite assembly operation and assure the presence of a washer in each assembly. They are generally available in various combinations of head styles and washer types.

SEPARATION - The state of no compressive load between mating parts local to the fastener. For a joint designed to maintain a seal, it is further defined as any condition that enables a liquid or gas to penetrate the seal at an unacceptable rate. Also referred to as Gapping.

SEPARATION LOAD - The minimum applied tensile load that causes separation.

SEPARATION-CRITICAL JOINT - A joint that fails to function as required if separated.

SERMAGARD 1105 (ASTM F1428) - Sermagard 1105 is a ceramic-metallic sprayed basecoat that at 1 mil of thickness or more affords 3000-4000 hours of ASTM B117 salt spray resistance, with an appropriate topcoat. It can be used at high temperatures. It is extremely effective in salt atmospheres. The Sermagard 1105 process involves curing at high temperatures (minimum of 750 deg. F) and subsequent burnishing with appropriate blast media to achieve conductivity. Sermagrad 1105 contains aluminum flake.

SERMAGARD 1280 - Sermagard 1280 is a fluorocarbon topcoat, which when applied to Sermagard 1105 basecoat gives superior corrosion resistance and UV protection.

SERRATIONS - Notches or grooves in the metal. Can be straight or spiral

SERVICE LIFE - All significant loading cycles or events during the period beginning with manufacture of a component and ending with completion of its specified use. Testing, transportation, lift-off, ascent, on-orbit operations, descent, landing, and post-landing events are to be considered.

SERVICE LIFE FACTOR - A multiplying factor to be applied to the maximum expected number of load cycles in the service life to determine the design adequacy in fatigue or fracture.

SET (Spring Term) - Permanent distortion in length or position which occurs when a spring is stressed beyond the elastic limit of the material.

SET SCREWS - A set screw is a threaded fastener that is typically used to hold a sleeve, collar, or gear on a shaft to prevent relative motion. It is a threaded member that normally does not have a head. Unlike most other threaded fasteners, it is basically a compression device normally used to generate axial thrust. Various socket types are provided to allow the set screw to be rotated. These types include hexagon socket, fluted socket, torx socket, screwdriver slot and square head. Various point designs are available (the part of the set screw that rotates against the shaft being secured) and include:

• Cup - Hollowed end, is the most commonly used point style. Used when the digging in of the point is not undesirable.
• Cone - Pointed end, this type generates the highest torsional holding power and is typically used for a permanent connection.
• Oval - Rounded end that is typically used when frequent adjustment is required. The oval end prevents/reduces indentation.
• Flat - Cause little damage to the shaft and are used when frequent adjustment is required.
• Dog - Flat end with the threads stopping short of the end with the end fitting into a hole.

SETDOWN - A dimension used to check for the proper amount of interference fit on a tapered insert assembly. Also the distance that a tapered insert is pressed into a case for assembly.

SETSCREWS & KEYWAYS - When a setscrew is used in combination with a key, the screw diameter should be equal to the width of the key. In this combination, the setscrew holds the parts in an axial direction only. The key, keyseat and keyway assembly carries the torsional load on the parts.

SETUP - Preparing a header, threader, CNC machines to perform a job.

SETUP TIME - The time required to change over a machine or process from one item or operation to the next item or operation. This dime can be divided into: 1. Internal: Setup work that can be done only when the machine or process is not actively engaged in production. 2. External: Setup work that can be done concurrent to normal operations.

SEX BOLTS - Are mating fasteners provided in a set, consisting of a female barrel nut and a mating screw.

SHAFT DIAMETER (DS) - This dimension represents the outside diameter of the assembly where an external retaining ring is installed.

SHAFT STRENGTH (SS) - An index of the quality of a material through a mathematical expression which divides the force required to a shear a material by it cross-sectional area.

SHANK - That portion of a headed fastener which lies between the head and the extreme point. Also called the Body.

SHANK - NASA-ASME B18.12-2001 That portion of a headed fastener that lies between the head and the extreme point end.

SHANK - (1) Bolt or Screw 0 the section under the head. (2) Other parts - usually a long cylindrical portion of the part.

SHANK - The entire outer portion of a blind threaded insert exluding the head. the counterbore and the threads are both contained within the shank. Shank diameters are typically just under the minimum mounting hole diameter with a modest minus tolerance applied.

SHANK (DRIVER BIT) - The shank is the end of a bit grasped by the chuck of a tool

SHANK (NAIL ANATOMY) - The length of the nail between the head and the point; may be smooth, or may have rings or like screw threads for greater holding power

SHANK DIAMETER - The diameter of the shank or the smooth part of a fastener above the threads.

SHANK LENGTH - A dimensional length from the fastener head to the tail

SHANK LENGTH - The total axial length of shank plus undercut plus displacer (definition #1) After a self-clinching fastener has been properly installed in the sheet, the distance from the top of the sheet to the end of the shank is also the shank length (definition #2)

SHANK RIBS - This feature is found on wood screws. These reduce the drive torque required during installation. Helps prevent the wood splitting, particularly useful on the longer lengths and larger diameters. Cleans the hole when securing two pieces of wood together preventing jacking

SHAVE - A metal removal process by cutting, usually small amounts.

SHAVING - Term used to describe the operation of knurling, cutting the undercut, and trimming the shank diameter on concealed head studs.

SHEAR - Force that tends to divide an object along a plane parallel to the opposing stresses.

SHEAR - DOUBLE - When a fastener or other component is loaded in such a way that one shear plane acts through the part and if failure were to occur, there would be three separate pieces.

SHEAR - SINGLE - When a fastener or other component is loaded is such a way that one shear plane acts through the part and if failure were to occur, there would be two separate pieces.

SHEAR DOWN - A small area usually under the head or shoulder where some material has been displaced into the tail or shank.

SHEAR FASTENER - A fastener whose primary function is the resist forces which tend to shear it.

SHEAR FORCE - A force that is applied perpendicular to the fastener between longitudinal axis. Generally, a fastener sees a shear force when the clamping members it is securing shift relative to each other.

SHEAR PLANE - The two-dimensional plane created by the contact of two surfaces in a shear joint.

SHEAR STRENGTH - The maximum load that can be supported prior to fracture when applied perpendicular to the fastener's longitudinal axis. Typically given in PSI as the load in pounds to cause fracture divided by the cross-sectional area in square inches of the part along the shear plane. As a rule, shear strength is two-thirds of tensile strength.

SHEAR STRESS AREA - An area perpendicular to the fastener axis which is based on the root diameter (minor diameter) of externally threaded bolt or screw.

SHEAR-TO-FEATURE - Shearing on an edge of stock to an exact dimension from an already existing feature.

SHEAR-TO-FEATURE - Process by which an edge of stock is sheared to a precise dimension from an existing feature.

SHEARING - Cutting force applied perpendicular to material causing the material to yield and break.

SHEARING - The application of a cutting force perpendicular to the material, resulting in yielding and breaking.

SHERARDIZING - A cementation process where zinc dust is heated to a temperature near its molten point and is brought into intimate contact with the steel surface to form an iron and zinc coating on the steel by diffusion.

SHIELD - (1) A non-conducting barrier positioned so as to alter the current distribution on an anode or cathode. (2) To alter the current distribution of an anode or cathode by the interposition of a non-conductor.

SHIM - A thin spacer of sheet metal used for adjusting.

SHOE - A holder used as a support for the stationary portions of forging and trimming dies.

SHOJINKA - Continually optimizing the number of workers in a work center to meet the type and volume of demand imposed on the work center. Shojinka requires workers trained in multiple disciplines and a supportive work center layout (such as U shaped or circular).

SHORT NUT - In application when the threaded fastener does NOT go beyond the top edge of the nut. It is recommended that threads protrude 3 threads above the nut.

SHORT-RUN STAMPING - Ideal for small projects and prototypes, short-run metal stamping does not require much upfront tooling to produce a component. The custom nature of short-run stamping operation can create a higher price per piece, but the lack of upfront tooling troughtout the run can make the method cost-efficient for some projects.

SHORTENING - The amount of decrease in overall length that occurs when a blind threaded insert is installed. It is typically slightly less than the free counterbore length minus two times the wall thickness. Inserts shorten more when installed in min grip than when installed near max grip, as a result, the installed height on the blind side of the panel is essentially constant, regardless of grip

SHOT BLASTING - A process of cleaning forgings by propelling metal shot at high velocity by air pressure or centrifugal force at the surface of the forgings.

SHOT PEENING - A process whereby hard, small, spherical objects (such as metallic shots) are propelled against a metallic surface for the purposes of cleaning or descaling that surface. Impacting the surfaces of the spring with pellets to induce compressive stresses and thereby improve fatigue life

SHOULDER - An enlarged portion of the body of a threaded fastener or shank of an unthreaded fastener, which contacts the top surface of material being fastened.

SHOULDER - The portion of a part or tooling component between two different diameters.

SHRINK FIT - A method of assembling an insert into a case with an interference fit. The case is heated to expand the inside diameter for assembly. Upon cooling the case will support the insert.

SHRINK SCALE - A measuring scale or rule, used on die layout, on which graduations are expanded to compensate for thermal contraction (shrinkage) of the forging during cooling.

SHRINKAGE - The contraction of metal during cooling after hot forging. Die impressions are made oversize according to precise shrinkage scales to allow the forgings to shrink to design dimensions and tolerance.

SHUT HEIGHT - For a press, the distance from the top of the bed to the bottom of the ram with the stroke down and adjustments up. In general, it is maximum die height that can be accommodated for normal operation, taking the bolster plate into consideration.

SHUT HEIGHT - The distance from the face of the dies to the face of the wedge at front dead center.

SHUT HEIGHT - The dimension in a die or press taken between the ram and bed when the ram is down and the adjustment is up. The shut height is typically equal to the maximum die-height that can be accommodated when taking the bolster into consideration.

SHUTS (COLD) - Faults produced in a forging by incorrect tool design or incorrect flow of steel that results in the formation of a crack in the forging surface.

SI - The International System of Unites. The modern form of the metric system. World's most widely used system of unites.

SIDE LOAD - The load applied to the fastenr parallel to the clinched panel at a given distance from tdhe panel dthat will cause the clinch feature to fail or yield the panel or fastener. Thinner panel may yield, thicker panel will cause the clinch feature to fail either by push-out on the bending compression side or pull-thru on the bending tension side. Typically, failure occurs when the bending moment resulting from the side load and distance exceeds the bending strength of the installed fastener. Side loads at other distances can be estimated by computing the bending moment from the published load and distance and then dividing by the distance of interest.

SIDE THRUST - Lateral force exerted between the dies by reaction of the forged piece on the die impressions.

SILICON - A non-metallic substance that adds strength and toughness to copper to help for a bronze alloy.

SILICON BRONZE - Alloy consisting of 95-98 percent copper plus a small amount of silicon added for strength and 1% Manganese. Silicon bronze is non-magnetic with a high degree of thermal conductivity and high corrosion resistance against sea water, gases and sewage. More resistant and tougher than brass. It is widely used in the electrical industry.

SILVER - A slender fragment of splinter that is a part of the material, but that is incompletely attached. A torn fiber of metal forced into the surface of a forging.

SILVER, ELECTROPLATED - Decorative, expensive and excellent electrical conductor. It resists thread galling when mated parts are under extreme pressure or exposed to extreme heat.

SINGLE ELEMENT - A term applied to gauging methods and to thread parameters (usually P.D.). Which implies that only one element is being considered. Singe element readings ignore the effects of other thread elements that would contribute to functional readings. The readings over wires is a single element reading of pitch diameter only.

SINGLE EXPANSION ANCHOR - The anchor is made of three pieces that are preassembled. The anchor body is made from Zamac, a die cast zinc alloy. The internal lugs are a cone shaped nut. A spring band made from low carbon steel and zinc plated holds the anchor body and internal lugs together.

SINGLE PIECE FLOW - A situation in which one complete product proceeds through various operations like design, order taking, and production, without interruption, black flow or scrap.

SINGLE POINT TKO - A tool side kickout design that uses a single intermediate rod between the TKO lever or rod in the heading slide and the tooling. Can be used to push a single pin on the centerline of the tool or to push a filler and spider pins for a kickout sleeve.

SINGLE THREAD - A single-start thread having lead equal to the pitch.

SINGLE-START THREAD - Having one ridge wrapped around the cylinder.

SINKER (NAIL) - The most common nails used in framing today; same thin diameter as a box nail; cement coated; the bottom of the head is tapered like a wedge or funnel and the top of the head is grid embossed to keep the hammer strike from sliding off; often used for construction, carpentry and framing.

SINKING - The operation of machining the impression of a desired forging into die blocks.

SIPOC - A term implying a high-level process map focusing on suppliers, inputs, processes, outputs and customers.

SIX SIGMA - A concept that implies a highly disciplined approach to deliver near-perfect products and services on a consistent basis. The value originates from a +4.5 sigma test that accomplishes a + 1.5 sigma shift over time.

SIZE - To form to final dimensions.

SIZING - Secondary forming or squeezing operations needed to square up, set down, flatten, or otherwise correct surfaces to produce specified dimensions and tolerances. Often accomplished with a coining press

SKIDMORE-WILHELM BOLT TENSION CALIBRATOR - The Skidmore-Wilhelm bolt tension calibrator is a hydraulic load cell used to determine the tension in a bolt or other threaded fastener. The tension in the bolt compresses fluid in a hydraulic cylinder, a pressure gauge connected to the cylinder is then calibrated to read in terms of force rather than pressure.

SKILLS MATRIX - A work cell visual control depicting all work activities. It provides assistance in the cross-training of team members.

SKINNING - A surface condition where a small portion of the part material has been sheared and pushed into another location.

SKIRT - A thin rim that is parallel to the axis of a part. Examples would be the thin radial projection on top of the hex or spark plug shells or Nyloc nuts.

SLEEVE ANCHOR - A post-installed mechanical anchor consisting of a steel stud with nut and washer, threaded on the top end and a formed uniform tapered mandrel on the opposite end around which a full-length expansion sleeve formed from sheet steel is positioned. The anchor is installed in a pre-drilled hole and set by tightening the nut by torquing thereby causing the expansion sleeve to expand over the tapered mandrel to engage the base material.

SLEEVE KICKOUT - A design using a thin walled sleeve to strip a hollow part off of a pin and to eject the part out of the tool/die cavity. The sleeve is usually kicked with 3 or 4 spider pins.

SLENDERNESS RATIO - Ratio of spring length (Lo) to mean coil diameter(D).

SLIDE - The part of the press that reciprocates linearly and to which the punch or upper die is affixed.

SLIDE ADJUSTMENT DEVICE - A component which consists of a worm shaft and worm gear and enables the die height to be adjusted using a punch-button control. The slide adjustment device is motorized and outputs a digital readout.

SLIDE ADJUSTMENT LOCKING DEVICE - A mechanism that prevents unintended change in the press shut height when subjected to heavy stamping loads.

SLIDE FORMING - A high-volume stamping process in which a machine with multiple slides sequentially performs various operations (i.e. blanking, piercing, forming etc.).

SLIDE LOCKING DEVICE - A mechanical device which prevents inadvertent slide movement on hydraulic presses.

SLIDING DIE / TOOL - A tool design allowing the tool or die case assembly to move axially. Used for the backward extrusion of a hole into a part, piercing, or the upsetting of a preform shape.

SLIP-CRITICAL CONDITION - The high-strength bolt clamps the connected parts in such a way that the shearing force is resisted by the friction between the parts, not by the shear on the body of the bolts. This is often denoted on drawings as (SC) (i.e. A325-SC). If slip occurs, the integrity of the joint could be compromised. Considered a friction-type joint.

SLOT DEPTH - The slot depth of a headed fastener is the distance measured parallel to the axis of the fastener from the highest part of the head to the intersection of the bottom of the slot with the head or bearing surface. The slot depth on a nut or headless fastener is the distance measured parallel to the fastener axis from the top surface to the extreme bottom of the slot.

SLOT ECCENTRICITY - The amount that a slot in a slotted head is eccentric with the body of the fastener.

SLOT FURNACE - A common batch-type forge furnace where stock is charged and removed through a slot or opening.

SLOT WIDTH - The distance measured in a plane perpendicular to the axis of the fastener over the interception of the sides of the slot with the head surface of a headed fastener or top surface of a nut.

SLOTTED HEAD - A head having a single horizontal indentation slot centered across its top surface and is driven by a "common blade" or flat bladed screwdriver.

SLOTTED SHANK - The generic term for a Plusnut or Plus-Tite insert. Slotting the shank allows larger grip range and also produces a larger bulb diameter than could be achieved with a slotted shank. Slotted shank parts typically have very thick walls and therefore high upset loads. They are sometimes pre-bulbed to reduce the upset load.

SLOTTING - The process of forming or cutting the slot on the head of a fastener during either the primary or secondary operation.

SLOW BLOCK - A block of heat=treated steel placed between a hammer anvil and a forging die to prevent undue wear to the anvil. Sow block are occasionally used to hold insert dies.. Also called Anvil cap.

SLUG - Scrap from a piercing operation. Slug Marks - surface defects caused by scrap being indented into the metal surface

SLUG - (1) Forging stock for one workpiece cut to length. See Blank. (2) Metal removed when punching a hole in a forging (also termed Punchout)

SLUG - (1) The small amount of material pierced from a hole. (2) A blank as prepared for forming.

SLUG DISCHARGE - Machine and tooling designs to allow for the removal of the pierced slug from either the tool or die and into the scrap discharge chutes of the machine.

SMALL LOT PRINCIPLE - Effectively reducing lot size until the optimum of one piece flow is realized.

SMED - (Single Minute Exchange of Die) Literally means changing a die on a machine in a minute or less. Often, the key to doing this is by converting internal setup time to external setup time. One common variation of SMED is the single digit setup, which requires performing a setup in a single digit number of minutes.

SMITH - The Blacksmith, forger or pressman.

SMITH FORGING - Flat die forging, Hand forging

SMITH HAMMER - Any power hammer where impression dies are not used for the reproduction of commercially exact forgings.

SMOOTH SHANK - Most common nail shank; relies on friction between the wood and the shank for holding power; effective in many, but not all, conditions.

SNAG GRINDING (SNAGGING) - The process of removing portions of forgings not desired in the finished product, by grinding.

SNAP DOWN - A term used to describe the movement of transfer fingers closing on a larger diameter and then moving to a smaller diameter during the part kickout motion.

SNAP TEMPER - A precautionary interim stress-relieving treatment applied to high hardenability steels immediately after quenching to prevent cracking because of delay in tempering them at the prescribed higher temperature.

SNUG TORQUE - The torque required to pull plats together so that direct contact occurs; often used in angle control tightening. The snug torque ensures that metal to metal contact occurs at all the interfaces within the joint. It is only at this point that the required angle of rotation starts in order that the bolt is tightened sufficiently. The snug torque is usually determined experimentally on the actual joint.

SNUG-TIGHTENED JOINT - A joint that resists shear loads by shear bearing only. Considered a Bearing-type joint.

SOAKING - Prolonged heating of a metal at a selected temperature.

SOCKET DEPTH - The distance measured parallel to the fastener axis from the intersection of the socket with the head surface to the extreme end of the socket. In socket head screws, the effective socket depth is most often specified as 'Key Engagement' which is the distance from the intersection of the socket with the head surface to that depth to which the key or wrench will penetrate, measured in a like manner.

SOCKET DIAMETER - The diameter measured in a plane perpendicular to the axis of the fastener over the intersection of the outermost extremities of the socket with the head surface.

SOCKET HEAD - A recessed head in which the sides of the recess are parallel to the body axis, into which a wrench fits. The recess is commonly hexagonal or fluted in form. Also designated as 'internal wrenching head.'

SOCKET WIDTH - The distance measured in a plane perpendicular to the axis of the fastener over the intersection of opposite sides of the socket with the head surface.

SOFT - The condition of a fastener which, though made from a material which can be, and normally is, hardened by heat treatment, has been left in the as-fabricated temper.

SOFT JOINT - A joint in which the plates and material between the nut and bolt bearing surfaces have a low stiffness when subjected to compression by the bolt load. In such a joint, the bolt (or nut) typically must be tightened by two or more complete turns, after it has been torqued to the snug condition, before the full tightening torque is achieved. Often the placement of a gasket in a joint, results in a soft joint.

SOLDER PAD - Tinned aera on PCB over which Solder paste will be stenciled.

SOLDER PASTE - Solder and Flux slurry

SOLID HEIGHT - Height of a spring when fully compressed to extent that each and every coil is in contact with the next.

SOLUTION ANNEALED (CARBIDE SOLUTION ANNEALED) - A process of heating and removing carbide precipitants (carbon that has broken loose from its stainless steel solution) by heating raw material or a finished fastener to over 1,850 degrees and cooling it quickly, usually in water, so carbon content goes back into the stainless solution.

SOLUTION HEAT TREATMENT - Heating an alloy to a certain temperature and holding at that temperature, allowing for a second element to form a solid solution with the base metal. Then the metal is rapidly cooled to retain the constituent solution.

SOLVENT DEGREASING - Cleaning by means of organic solvents.

SPACING: CRITICAL SPACING - The least anchor spacing distance at which the allowable load capacity of an anchor is applicable such that the anchor is not influenced by neighboring anchors.

SPACING: MINIMUM SPACING - The least anchor spacing at which the anchors are tested for recognition.

SPALLING - A chipping or flaking of a surface due to any kind of improper heat treatment or material dissociation.

SPALLING - A chipping or flaking of a surface due to any kind of improper heat treatment or material dissociation.

SPANNER HEAD - The Spanner head or Snake-Eyes™ screw drive use two round holes opposite each other and is designed to prevent tampering. Other informal names include Pig Nose, Drilled Head or Twin Hole.

SPC - An abbreviation for (Statistical Process Control). Used to judge the repeatability and consistency of a process.

SPECIAL FASTENER - A unique fastener which differs in any respect from recognized published standards, usually a new design but can be a modified standard part. The fastener is usually designed for a particular application. AKA as a non-standard or modified fastener.

SPECIAL THREAD GEOMETRY - Various thread geometry are being introduced on construction screws which these special thread designs with a next generation lubrication system ensures almost half the torque is required to drive in faster, with less effort

SPEED-FASTENING SYSTEM - A speed-fastening installation tool into which a magazine of speed fasteners is loaded. The system facilitates very rapid installation rates.

SPHERICAL POINT - An oval point in which the point radius is equal to half the shank diameter.

SPHEROIDIZED STEELS - A steel that has been heat treated in such a way as to produce a spherodite microstructure (i.e. a microstructure with small spheres of cementite surrounded by a matrix of ferrite as opposed to layers of cementite).

SPIDER PINS - Either three or four pins working as a group between the kickout rod or filler and a kickout sleeve to remove the formed part from the tool or die.

SPIN-OUT - The torsional holding power of an insert relative to the panel in absence of any clamp load. It is typically measured by holding the panel, inserting a screw from the thread end of the part until it bottoms against the part and applying torque until failure. For inserts with round shanks the typical failure mode is the insert spinning in the panel. For keyed inserts or inserts with hex shanks the values will typically be higher and the mode of failure may switch to torsional failure of the insert or thread stripping due to the induced load.

SPIN-PULL - A type of tool that applies the upset load by first turning a mandrel into the threads of the insert with a low torque and then apply a pulling force to the mandrel. After the part has been upset by the pulling action, the mandrel is turned in the opposite direction to remove it. For this reason, a more proper term for this type of tool that is sometimes used is spin-pull-spin. Compared to spin-spin tools, these tools are more complex, heavier, more expensive and more difficult to setup. However, a smooth nosepiece that will not mar the insert head can be used.

SPIN-SPIN - A type of tool that applies the upset load by turning a threaded mandrel into the threads of the insert. The mandrel is driven by an air motor through reduction gearing. A thrust bearing is used to reduce frictional torque resulting from the applied load. Spin-spin tools are light weight and inexpensive and come with varying amounts of gearing. As thread size increases additional gearing is used to increase torque output at the expense of speed. The stall torque is adjusted by air pressure. Operation is simple, spin in to stall and then reverse the trigger and spin out. Hence the spin-spin terminology. To prevent the insert from rotating, a serrated nosepiece must be used and therefore significant marring of the insert head occurs.

SPINWALL TECHNOLOGY™ - A trademark used by AVK to describe how the technology of thin wall parts differs from that of thick wall parts. The major difference they claim is the radial expansion of the counterbore to completely fill the mounting hole before the bulb is formed.

SPIRAL RIBS - Spiral Ribs on the underneath surface of a countersunk head design screws used for woodworking with panels and hardwood. Spiral Ribs limits splits on the wood surface and seats flatly and smoothly on the work piece. Keeps the surface free of tailings around the edges of the screw head.

SPLINE - Raised portions of a shaft which fit into corresponding grooves in a pulley or some sliding member. They can either permit end movement of can be used as a permanent fastening.

SPLIT DIE - A die made of parts that can be separated for ready removal of the workpiece. Also known as segment die.

SPLIT DRIVE ANCHOR - The anchor that is all steel, one piece available in two head styles - flat countersunk and round. These anchors are made from heat-treated carbon steel and are thoroughly hardened. At opposite end of the head, the anchor is sheared into two pre-expanded halves.

SPLITTER IMPRESSION - (1)A die cavity used to divide laterally or split the material being worked so that it better covers the impression and reduces forging load; (2) A die cavity used to cut the material apart in the desired section by means of a shearing action.

SPOKES - Solid portion of the stencil design that holds the center of the hole to the rest of the stencil pattern.

SPOT FACE - Circular flat surface as a bearing area for hardware.

SPOT FACE - (1) A bearing area for hardware that is circular and flat in nature. Also called a sump. (2) The smooth area around the hole for a fastener.

SPOT-FACE - To finish a round spot on a rough surface, usually around a drilled hole, to give a good seat to a screw or bolt head, cut, usually 1/16 inch deep.

SPOTTING OUT - The delayed appearance of spots and blemishes on plated or finished surfaces.

SPRING BACK - Partial rebounding of formed material caused by its elasticity.

SPRING CLIP - One-piece fastener that holds inserted components through spring tension and does not easily come loose during vibrations. The strength of a spring clip is directly influenced by factors such as the material used, its thickness and design.

SPRING INDEX - Ratio of mean coil diameter (D) to wire diameter (d).

SPRING RATE - Amount of lbs. it takes a spring to move 1 inch

SPRING-LOADED - A device having a separate movable component that is biased on one direction by a spring.

SPRINGBACK - (1) The elastic recovery of metal after stresding. (2) The extent to which metal tends to return to its original shape or contour after undergoing a forming operation. This is compensated for by overbending or by a secondary operation of restriking.

SQUARE - (1) Square Up: A forming operation to make the ends of the cutoff blank more perpendicular to the sides. (2) Square the Shoulder: To reduce the radius and further sharpen the corner.

SQUARE DRIVE - A Square screw drive uses four-sided fastener heads which can be turned with an adjustable wrench, open-end wrench, or 8 or 12 point sockets. Square head machine bolts were very common in the 19th and early 20th centuries, when it was cheaper to manufacture than most other drives, it is less common today because of the external hex drive cap screws, bolts or lag screws as it allows better access for wrenching. Also on the Square Head Set Screws.

SQUARE HEAD - A four sided head common on square head bolts and square head lag screws. Four sided machine screws would be considered a "Special" design head for a specific application. Four headed set screws are common in machine tools and fixtures.

SQUARE NECK - A style of neck consisting of a square shoulder formed integral with the underside of the head. E.g. Carriage bolts and step bolts.

SQUARE THREAD - A thread with box-like ridges. The crests are at 90 degree angles from the flanks.

SQUARENESS - Measure of perpendicularity of adjacent edges or surfaces.

SQUARENESS OF ENDS (SPRING TERM) - Angular deviation between the axis of a compression spring and a line normal to the plane of the ends.

SQUARENESS UNDERLOAD (SPRING TERM) - Same as in Squareness of Ends, except measured with the spring under load

SSD - Single-on-Demand (SSD) is a mode of operation where the press automatically makes a single stroke based on input rom upstream or downstream processes. Upon receiving the appropriate signal, the press will make a single stroke and stop.

SSS - Refers to the five Japanese words: seiri, selton, seiso, seiketsu and shitsuke which are shorthand expressions for the principal techniques of main workplace. Some companies add a 6S for Safety. Seiri (Sort) Eliminating everything not required for the work being performed. Selston (Straighten) The efficient placement and arrangement of equipment and material. Seiso (Shine) Maintaining tidiness and cleanliness in the workplace. Seiketsu (Standardize) An ongoing standardized, improvement process. Shitskue (Sustain) Discipline with leadership.

STABILIZING TREATMENT - A treatment applied to stabilize the dimensions of a workpiece or the structure of a material such as (1) before finishing to final dimensions, heat a workpiece to or somewhat beyond its operating temperature and then cooling to room temperature a sufficient number of times to ensure stability of dimensions in service; (2) transforming retained austenite is those materials that retain substantial amounts when quench hardened (see cold treatment); (3) heating a solution-treated austenitic stainless steel that contains controlled amounts or titanium or niobium plus tantalum to a temperature below the solution heat treating temperature to cause precipitation of finely divided, uniformly distributed carbides of those elements, thereby substantially reducing the amount of carbon available for the formation of chromium carbides in the grain boundaries on subsequent exposure to temperatures in the sensitizing range.

STAINLESS STEEL - AUSTENITIC - Also called 18-8 or 300 series, most common stainless steel. They are highly corrosion resistant due to the presence of approximately 18% chromium and 8% nickel. Austenitic stainless steel has an FCC structure. Nonhardenable by heat treatment. Can pick up magnetic properties through cold working.

STAINLESS STEEL - DUPLEX - Contains a mixed microstructure of austenite and ferrite (duplex) with an ideal mixture of equal parts of austenite and ferrite. These steels have superior strength and corrosion resistance when compared to austenitic stainless steel and contain high amounts of chromium.

STAINLESS STEEL - FERRITIC - Corrosion resistant steel contains 12%-18% chromium, little to no nickel, and less than 0.2% carbon. Magnetic and nonhardenable by heat treatment, these may contain lead. Common Grades: 430

STAINLESS STEEL - MARTENSITIC - Corrosion resistant steel which contains 12%-18% chromium, little to no nickel, and enough carbon to be heat treated. It is magnetic. Common Grades: 410 & 416

STAINLESS STEEL - PRECIPITATION HARDENED - Stainless steel that has the corrosion resistance of austenitic stainless steel and better strength characteristics than some of the martensitic grades. This is accomplished through complex and lengthy form of heat treatment called age-hardening (due to the time required to complete it. Common Grades: 16-4, 17-7, 630, A-286

STAKING - Method of fastening using displaced material for retention.

STAMP - To make a mark into the metal (as to stamp a trade mark or code on screw heads)

STAMP (MARKING) - An operation performed to identify the particular forgings as specified or requested by the customer.

STAMPING - This process takes a piece of sheet metal and forms a part by cutting and or folding the metal. This is typically a high-speed process that yields many pieces in a short period of time. Typical method to manufacture flat washers.

STAMPING - This process takes a length of sheet metal and forms a part by cutting and folding the metal. This typically is a very high-speed process that yields many pieces in a very shot period of time

STANDARD FASTENER - A fastener which conforms in all respects to recognized standards. Documented agreements containing technical specifications and other precise criteria to be used as constants and define characteristics that ensure the that the material, products, processes, and services are fit to their purpose.

STANDARD TORQUE - 2/3 of initial installation value i.e. MIL spec., plus requirement of removales and clamp load. Example: If the maximum initial installation torque is 100 in. lbs. It would be two-thirds at 7=66 in. lbs. with a potential variance ranging between 60-75 lbs. NYLOK

STANDARD TORQUE - 2/3 of initial installation value i.e. MIL spec., plus requirement of removals and clamp load. Example: If the maximum initial installation torque is 100 in. lbs, it would be two-thirds at 66 in. lbs with a potential variance ranging between 60-75 in.lbs.

STANDARD WORK - A precise description of each work activity, specifying cycle time, takt time, the work sequence of specific tasks and the minimum inventory of parts needed to conduct the activity.

STANDOFF - A tubular device, usually threaded, for spacing or stacking components.

STANDOFF - A tubular device, usually threaded, for spacing or stacking components.

STATIC FRICTION - Friction at rest; a force is required to initiate relative movement between two bodies - static friction is the force that resists such relative movement. Sometimes referred to as stiction.

STATIC LOAD - A load whose magnitude does not vary appreciably over time.

STATION - A regular stopping place in the die during the forging sequence.

STEAM HAMMER - A type of drop hammer where the ram is raised for each strike by a double-action steam cylinder and the energy delivered to the workpiece is supplied by the velocity and weight of the ram and attached upper die driven downward by steam pressure. Energy delivered during each stroke may be varied.

STEEL STAMPED - General term used to describe a part or component manufactured by a metal stamping machine.

STEM - See Shank

STEM - The component part of a breakstem fastener that is retained within the body. Also known as the mandrel.

STEM RETENTION - The force required to separate the stem from the body of an uninstalled breakstem fastener.

STENCIL - Screening sheet used to apply solder paste to exposed areas of a PCB.

STEP - That portion of a headed stud blank to which the root and roll out will be applied. Sometimes referred to as the thread rolling step which canbe slightly misleading as threads do not get rolled on to the step.

STEP-LOCK BOLTS (SLB) - The step-lock bolt is a thread form that has been modified to resist vibration loosening. The thread has several horizontal portions (i.e. no lead angle) whose purpose is to prevent torsion being developed in the bolt as a result of the loosening purpose. It is those horizontal portions that are known as steps. Published literature indicates that the thread form performs well when tested on a transverse vibration test machine. However manufacturing difficulties may prevent its widespread adoption.

STIFFENING RIB - Embossed feature in a sheet metal workpiece which is added to make the part more rigid.

STOCK - The material to be forged regardless of form. Also an individual piece of metal used to produce a single forging.

STOCK FASTENERS - Fasteners readily available from a fastener manufacture or distributor. Typically, commercial, or proprietary brand name fasteners.

STOCK GAGE TIP - An adjustable stop at the cutoff station that controls the length of the sheared blank. Used on machines with rotating feed rolls that feed in the wire.

STOCK MARKS - In cutting forging stock to specified length for a die-forged part, the ends of the bar are always contain surface imperfections caused by the cutting tool; these are often retained on the surface of the finished part. If pronounce, such marks are removed by light grinding. On parts where repeated indications of stock marks are encountered, efforts are usually made to eliminate them by conditioning the stock ends prior to forging by polishing the cut ends and beveling the edge of the cut.

STOPPING OFF - The application of a resist to any part of a cathode, anode or rack.

STRAIGHT ACROSS TRANSFER - A transfer with cam controlled opening and closing fingers that moves the parts in a straight line between forming stations. Typically used for long shank type products.

STRAIGHT INSERT - An insert design where the outside diameter of the insert is parallel to the axis of the insert. In some cases there can be a very slight taper towards the rear of the insert to aid in the assembly of the insert into the case.

STRAIGHTEN - Finishing operation for correcting misalignment in a forging or between different sections of a forging. Straightening may be done by hand, with simple tools, or in a die in forging equipment.

STRAIGHTEN COIN - A combination coining and straightening operation performed in special cavity dies designed to impart a specific amount of working in specified area of the forging to relieve stresses set up during heat treatment.

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

STRAIGHTEN HAND - A straightening operation performed on a surface plate to bring a forging within straightness tolerance. Frequently, a bottom die from a set of finish dies is used instead of a surface plate; hand tools used include mallets, sledges, block, jacks and oil gear presses, in addition to regular inspection tools.

STRAIGHTENER ROLLS - A tooling component in the wire line of a machine equipped with a wire straightener. They are either grooved for a specific wire diameter and must be changed when the incoming wire diameter changes or they can have a V groove to cover a range of incoming wire diameters.

STRAIGHTENING - A process by which a long, slender metal part is straightened to a specified tolerance. Typically following hardening of the material. This can be a cold mechanical process performed on a straightening press of it can involve the use of heat in a fixture or die.

STRAIGHTENING - A process by which a long, slender metal part is straightened to a specified tolerance, typically following hardening of the material. This can be a cold mechanical process performed on a straightening press or it can involve the use of heat in a fixture or die.

STRAIN - Deformation produced on a fastener by an external force.

STRAIN HARDENING - The increase in hardness, and hence strength, resulting from plastic deformation at a temperature below the recrystallization range. Sometimes called work hardening.

STRAIN HARDENING - An increase in hardness and strength caused by plastic deformation at temperatures below the recrystallization range. Also known as Work Hardening

STRAIN RATE - The rate at which metal is deformed.

STRAIN-RATE SENSITIVE - Alloy that can be forged only at low rates of deformation.

STRAY CURRENT - Current through paths other than intended circuit, such as through heating coils or the tank. Strike: (1) A thin film of electrodeposited metal which improves the deposition of subsequent coatings. (2) A solution specially formulated to obtain this film. (3) To electroplate for a relatively short time either in a bath of a composition or at operating conditions different from those of the subsequent process.

STRENGTH DESIGN - A design method in which an anchor is selected such that the anchor's design strength is equal to or greater than the anchor's required strength.

STRENGTH REDUCTION FACTOR - A factor applied to the nominal strength to allow for variations in material strengths and dimensions, inaccuracies in design equations, required ductility and reliability, and the importance of the anchor in the structure.

STRESS - The load per unit area tending to deform a material. Typically specified in units of MPa or PSI.

STRESS AREA - The effective cross-sectional area of a thread when subjected to a tensile force. It is based upon a diameter which is the mean of the pitch (or effective) and the minor (or root) diameters of the thread. The use of this diameter stems from the work of E.M. Slaughter in the 1930's. He completed carefully controlled tests using various sizes of standard threads and compared their strength with machine bars made form the same bar of material. He found that this mean diameter gave results that agreed with the tensile test results in within about 3%. The error on the minor and pitch diameters was about 15%. Tests completed subsequent to these by other investigators have also shown that the stress diameter is a reasonable approximation of the thread's tensile strength. (Reference: Test on Thread Sections Show Exact Strengthening Effect of Threads. By E.M. Slaughter, Metal Progress, vol 23. March 1933 pp 18-20)

STRESS CORRECTION FACTOR - Factor that is introduced to make allowance for the fact that the distribution of shear stress across the wire diameter is not symmetrical.

STRESS CORROSION - Occurs when corrosion causes a highly stressed part (one that is pushed to its maximum tensile strength) to crack. Except for heat treated 400 series stainless, stress corrosion does not normally apply to austenitic stainless, brass, or bronze, since these metals are relatively ductile and not normally used for high tensile operations.

STRESS RANGE - The difference in operating stresses under minimum and maximum forces.

STRESS RELAXTION - The tendency of a material to release stress when placed under a constant load. A significant problem with bolting at high temperatures is a phenomenon known as stress relaxation. Creep occurs when a material is subjected to high temperatures and a constant load. Stress relaxation occurs when a high stress is present that is relieved over time; the stress is relaxed with a subsequent reduction in the bolt's preload. The only way to minimize the effects of stress relaxation is to use materials that have an adequate resistance to it as the product's operating temperature. The effect of bolt stress relaxation is to reduce clamp force provided by the bolts; this phenomena alone, will not fully loosen a joint.

STRESS RELIEVE - Heating to a suitable temperature, holding long enough to reduce residual stresses (in both cold worked or heat-treated parts) and then cooling to minimize the development of new residual stresses.

STRESS RELIEVE - Low temperature heat treatment for removing any residual stresses induced by edgwinding and/or forming.

STRESS RELIEVE - A process to reduce internal residual stresses in a metal object by heating the object to a suitable temperature and holding for a proper time at that temperature. This treatment may be applied to a relieve stresses induced by casting, quenching, normalizing, machining, cold working or welding.

STRESS RELIEVE - Heating a spring at a lower temperature to remove stress from coiling

STRETCHER LEVELED - A flattening process in which a material is stretched to achieve a desired flatness tolerance.

STRIKE - (1) (n) A thin film of metal to be followed by other coatings. (2) (n) A solution to deposit a Strike. (3) (v) To plate for a short time, usually at a high initial current density.

STRIKE ANCHOR - A displacement controlled type of expansion anchor. The body is steel with a hole down the interior length of the anchor. The hole is smaller in diameter at the opposite end of the threads where the slots are. One end of the anchor is threaded for a portion of its length and the opposite end has four equally spaced slots. A hardened nail is inserted into the interior hole in the anchor and is used to expand the slotted end of the anchor.

STRIP - A process or solution used for the removal of a coating from a basis metal or an undercoat.

STRIPPER - Mechanical hold-down device applied to the workpiece during the punching process.

STRIPPER - A lug or ring on the forging or an impression in the dies of a mechanical upsetter to ensure firm clamping of the workpiece in the gripper dies.

STRIPPER AT FACE OF DIE - A machine mechanism used to remove thin walled backward extruded parts from the extrusion pin when a kickout sleeve is not practical. The U shaped stripper tip moves between the part at the end of the die kickout stroke and the face of the die, A large spring on the die kickout pin then pulls the extrusion pin out of the part before the transfer starts to move.

STRIPPER BAR - A tooling component that ties the two intermediate kickout pin together for a two-point TKO tool design. The TKO rod pushes against the bar to move the intermediate pins.

STRIPPER INSERT - A tooling component pressed into the stripper plate for a two-point TKO tool design. This insert varies to suit removing hollow parts from the forming punch.

STRIPPER MARKS - Imprints on one side of the stock around pierced holes, caused by punch strippers.

STRIPPER PLATE - A tooling component for a two-point TKO design. It is on the front of the tool and fastened to two spring loaded pins. The springs pull the stripper plate back to its starting position after the TKO stroke is finished.

STRIPPER PUNCH - A punch that serves as the top or bottom of the die cavity and later moves farther into the die to eject the part or compact. See Ejector and Knockout.

STRIPPING - To damage or break the threads of a screw, nut, or bolt.

STRIPPING - Process of disengaging tooling from the workpiece.

STRIPS - Sheet material, sheared into narrow long pieces.

STROKE - RAM travel from top dead center (TDC) to bottom dead center (BDC).

STROKE - Slide movement in the vertical plane that occurs during the half cycle motion from the fully open to fully closed position , or vice versa.

STROKE - The amount of decrease in overall length that occurs when a blind threaded insert is installed. Therefore, it is numerically equal to the shortening. However, the term stroke is typically applied to spin-pull tools wheras the shortening term is applied to the insert. Most spin-pull tools have an internal stop, which limits the stroke. To setup these tools, the stroke must be properly adjusted so that the insert will be installed properly.

STROKE (UP OR DOWN) - The vertical movement of a ram during half of the cycle, from the full open to the full closed position or vice versa.

STRUCTURAL BOLTS - A heavy hex head bolt intended for use in structural applications. Most commonly graded as ASTM A325 or A490.

STRUCTURAL INTERGRITY - Inherent microstructural soundness of forgings as a result of achieving 100 percent density, uniform metallurgical structure and grain size, as well as the absence of porosity, segregation, large inclusions, and other non-forged part defects.

STYKFIT® 7 DRIVE - STYKFIT® 7 is a patented design which provides tight tolerance between bit and screw for a "stick-fit". Screws don not fall off the bit, even when bearing weight - perfect for assembly applications. Fast indexing, ease of use and improved installation times are the result. Looking to make gains in productivity and efficiency with a security screw? This is the answer.

SUB-SOW BLOCK (DIE HOLDER) - A block used as an adapter in order to permit the use of forging dies that otherwise would not have sufficient height to be used in the particular unit or to permit the use of dies in a unit where the shank sizes are different.

SUBSTANDARD FASTENERS - Fasteners that do not meet specified standards, or requirements related to fit, form and function.

SUBSTRATE - Any material layer under another. In zinc electroplated fasteners, the steel fastener would be the substrate as it is covered by a layer of zinc.

SUCK IN - A depression in the end of a solid part or around the hole of a hollow part resulting from the material flow and friction during the extrusion process.

SUCK-IN - A defect caused by the (sucking in) of one face of a forging to fill a projection on the opposite side.

SUPADRIV - Supdriv is very similar to Pozidriv in function and appearance. In greater detail, the Supdraiv screwhead is similar to Pozidriv but has only two identification ticks, and the secondary blades are larger. Drive blades are about equal thickness. The main practical difference is the driving screws into vertical surfaces: that close to a near vertical surface to drive the screws into the drivers, Supadriv has superior bite, making screw driving more efficient, with less cam out.

SUPERIMPOSED AC - A form of current which an alternating current component is superimposed on the direct plating current.

SUPERPLASTICITY - The ability of certain metals to develop extremely high tensile elongations at elevated temperatures and under controlled rates of deformation.

SUPPERALLOYS - A term broadly applied to iron-base, nickel-base, and cobalt-base alloys, often quite complex, that exhibit high elevated-temperature mechanical properties and oxidation resistance.

SUPPORTED KICKOUT - This is a special kickout pin design that gives additional support to the kickout pin during the kickout stroke. The design is used whenever the unsupported length of the kickout pin exceeds 10 to 12 diameters.

SURFACE ACTIVE AGENT - A substance that affects markedly the interfacial or surface tension of solutions even when present in very low concentrations.

SURFACE DISCONTINUITIES - Irregularities of a fastener. These may include cracks, head bursts, shear bursts, seams, folds, thread laps, voids, tool marks, and nicks or gouges.

SURFACE HEAT TREATMENT - A process that improves the hardness or other mechanical properties of the fastener in any surface area.

SURFACE MOUNT - Process of applying product to PCB by first stenciling solder paste then placing product on paste and finally heating entire assembly to melt the solder Also known as "reflow soldering."

SURFACE TENSION - That property, due to molecular forces, that exists in the surface film of all liquids and tends to prevent the liquid from spreading.

SURFACE TREATMENT - Any treatment which changes the chemical, physical, or mechanical properties of a surface.

SURFACE TREATMENT - General term denoting the treatment involving a modification of the surface. The term is also used in a restrictive sense excluding metallic coatings.

SWAGEFORM - High Performance Thread Rolling Screws feature a special Swageform design which consist of 3 - 4 forming lobes located pn the flank of the tapered lead threads 120 degrees apart. The initial contact of the lobes with the hole significantly reduces the installation drive torque. Swageform(r) screws produce no cutting chips as material is swaged during the tapping process and not cut. The swaging action associated with Swageform(r) screws produces a full form thread with less frictional contact, allowing a much lower drive torque.

SWAGING - The process in which the dimensions of an item are altered using dies into which the item is forced. Usually a cold working process. It is also a method whereby a reduced diameter of a fastener is deformed to secure it to a panel.

SWAGING - (1) Reducing the diameter of or rounding out a section of a forging by a series of blows, tapering the forging lengthwise until the entire section attains the smaller dimension of the taper. (2) Tapering forging stock by forging, hammering, or squeezing.

SWAGING - An operation whereby a reduced diameter of afastener is deformed to secure it to a panel. Also see self-expanding/crush clinch. Note: the atonym of a swaging self-clinching where the panel material is caused to deform.

SWELL NECK - A tapered or variable neck.

SYMMETRICAL THREAD - A symmetrical thread is one which has both flanks of the thread profile inclined at the same angle.