McGuire Glossary of Fastener Terminology

P - 223 terms

PHOSPHATE COATED - Wire - A surface coating to lubricate the wire surface. It has high pressure resistance.

PAN HEAD - Flat top surface rounded into cylindrical sides, and a flat bearing surface. For general applications. Can be substituted n most applications for round, truss or bind heads.

PANCAKE - A term used to describe an enclosed upset operation where the incoming blank diameter is increased as a preform for a subsequent forming operation.

PANCAKE FORGING - A rough forged shape, usually flat, that can be obtained quickly with minimal tooling. Considerable machining is usually required to attain the finish size.

PANEL - The material into which a self-clinchng fastener is installed. The fastener material must be harder than the panel material for the self-clinching technology to work.

PANEL FASTENER - A threaded screw, which is held captive to a panel and which, when disengaged from its main nut, remains fixed to that panel.

PANEL HARDNESS - A material specification for self-clinchng fasteners. A hardness measurement of the material used for a self-clinching fastener. It is also refereed to as sheet hardness and typically expressed as a Rockwell B scale hgardness with a maximum limit.

PAPP - Production Part Approval Process (PPAP) is a quality management system that helps manufacturers and suppliers communicate, review, and approve processes and procedures at all stages of the product design cycle.

PARALLELISM - The degree to which the two ground ends of a spring are parallel to each other.

PARENT MATERIAL - See Joint Material

PART NUMBER - Both the fastener manufacturer and the fastener distributor have a numbering system, usually unique to their company. There is no uniform part numbering system in the United States for commercial, commodity fasteners. There is a part numbering system for AN, MS, NAS and NASM fasteners, commonly known as Military Standards.

PARTING LINE - (1) The line along the surface of a forging where the dies meet, usually at the largest cross section of the part. Flash is formed at the parting line. (2) The plane that divides the two forging die halves.

PARTS SHUTE - Equipment used to direct pieces of metal cut from parts from the workspace into designated area.

PASCAL - An SI unit of pressure or stress. One pascal is equal to one Newton distributed over a square meter.

PASSIVATING - The process of dissolving ferrous particles and surface impurities from stainless steel by chemical means (normally a nitric acid dip) and to produce a passive film on the surface. The purpose is to improve the corrosion resistance of the surface. This layer is usually an oxide or nitride that is a few atoms thick. Under normal conditions of pH and oxygen concentration, passivation is seen to occur naturally in such materials as aluminum, magnesium, copper, stainless steel, titanium, and silicon.

PASSIVATING - Imparting passivity to a metal surface usually by dipping it into a medium (such as preparations containing chromic and/or phosphoric acid) forming a very thin protective surface film.

PASSIVATION - The spontaneous formation of a hard non-reactive surface layer that inhibits further corrosion. This layer is usually an oxide or nitride that is a few atoms thick. Under normal conditions of pH and oxygen concentration, passivation is seen to occur naturally in such materials as aluminum, magnesium, copper, stainless steel, titanium, and silicon

PASSIVATION - Describes the treating of a metal with a mild oxidant (such as nitric acid) to remove iron or iron compounds by dissolution. This action forms a protective passive film on the surface of the metal. The trace iron left behind from machining and fabrication can provide sites for corrosion if left untreated.

PASSIVATION OF STAINLESS FASTENERS - This process enhances stainless steel's corrosion resistance. The fasteners are dipped in a solution which removes surface imperfections and produces a slight film on the surface of the parts.

PASSIVE FILM - The major characteristic of stainless is its ability to form a thin layer of protection called a passive film on its outside surface. This film results from a continual process of low-level oxidation, so oxygen from the atmosphere is needed for the passive file to exist. Once formed, it prevents further oxidation/corrosion from forming.

PASSIVITY - The condition of a metal that retards its normal reaction in a specified environment and associated, with the assumption of a potential more noble than its normal potential.

PATENTING - A process of heat treatment applied to medium or high-carbon steel in wire making prior to the wire drawing or between drafts. It consists in heating to a temperature above the transformation range, followed by cooling to a temperature below that range in air or in a bath of molten lead or salt maintained at a temperature appropriate to the carbon content of the steel and the properties of the steel and the properties required of the finished product.

PCB - Laminant fiberglass flat sheet

PDCA - A general problem solving methodology representing the steps: plan, do, check, and act.

PDSA - Deming's modified problem solving methodology representing the steps: plan, do, study and act.

PEAK DRIVE TORQUE - Amount of force required to pull the members of a joint together; the point at which clamp begins to generate.

PEARLITE - A metastable lamellar aggregate of ferrite and cementite resulting from the transformation of austenite at temperatures above the bainite range.

PEEK(R) (PLASTICS) - Polyetheretherketone is a new material which has exellent chemical resistance and is rated for continuous service to 470F. It is tough and strong with low creep, and has the best fire safety rating of all thermoplastics. It tolerates radiation to 1100M rads without undergoing significant change. Applications include engine parts, aerospace components and other uses which require PEEK(r) unique qualities.

PEEL-TYPE TAIL - A rivet body which is designed to split open on the blind side of the joint during the installation to provide large blind-side bearing area in soft materials.

PEELING - The detachment or partial detachment of an electrodeposited coasting from a basis metal to undercoat.

PEENING - The process of working a metal's surface to improve its material properties, usually by mechanical means such as a hammer blows, by blasting with shot (shot peening) or blasts of light beams with laser peening. Peening is normally a cold work process, with laser peening being a notable exception.

PENETRATION - (1) Depth of cutting operation before breakout occurs. (2) In welding, the depth of material through which fusion occurs. The depth at which material is cut through exertion of a force, prior to the occurrence of material breakout.

PENETRATION RATE - Depth rate of working.

PENTA PLUS™ DRIVE - PENTA-PLUS™ is designed in configuration to keep-out Torx-Pin, Hex-Pin and all other tamper-resistant bits sold commercially. Screws and bits are controlled through a customer database at Bryce Fastener.

PENTAGON DRIVE - A pentagon screw drive uses a five-sided fastener heads, and the fastener is known as a penta screw or penta bolt. It is designed to be intrinsically incompatible with many tools. Because it is five sided, an odd number, it cannot be turned by open-end or adjustable wrenches, which have parallel faces (and thus require a fastener with an even number of sides). Due to the difficulty of turning these fasteners without specialized (and uncommon) five-point wrenches such as hydrant wrenches, they ae commonly used for tamper resistant by public utilities on water meter covers, natural gas values, electrical cabinets and fire hydrants.

PENTALOBE - The Pentalobe screw drive is a five-pointed tamper-resistant system being implemented by Apple in it products. Often confused with the 5 point Torx screw drive! Versions are used on various products such as I-Phones and MacBook.

PERCENTAGE OF THREAD - Ration (in %) of the actual thread height to a value of .75H. .75H is the old value of theoretical thread height in the American National Thread Profile. Since the design thread height of the Unified National Thread Profile is only .625H, it is impossible to have a 100% thread. In fact, maximum thread percentage would be .625 over .75 or 83%.

PERFECTION - The complete elimination of Muda so that all activities, along a value stream, create value.

PERIODIC REVERS PLATING - A method of plating in which the current is reversed periodically. The cycles are usually no longer than a few minutes and may be much less.

PERMANENT SET - A ring that has been expanded or contracted to a point where its elastic properties have been exceeded and does not return to its original diameter is said to have taken a "permanent set".

PERMANENT SET (SPRING TERM) - A material is said to have a "permanent set" when it deflects so far that it exceeds its elastic properties and does not return to its original condition upon release of load

PERPENDICULARITY - Dimensional relationship of a part or datum located at right angles (90 Degrees) to a given feature.

PERT - An event oriented, project planning technique meaning program evaluation and review technique.

PES(R) (PLASTICS) - Crystal clear polyethersulfone has truly creep resistance, dimensional stability, and excellent mechanical properties. It can withstand continuous use in air and water at temperatures to above 350F. It has low flammability and minimal smoke emission during burning. Its weatherability and solvent resistance are also good. Since PES is sterilizable, it has a wide variety of medical applications. Other applications include electronic components of all types and structural parts

PFA (PLASTICS) - Perfluoroalkoxy resins, which are marketed under the PTFE/polyterafluoroethene(r) trademark, have properties similar to FEP and PTEE. However, unlike FEP, PFA may be used to temperatures of approximately 500F. While PFA shares PTFE'S chemical resistance and low coefficent of friction, it is also moldable, and extrudable material. Some applicaitons include packing and seals, cable sheathing, and fire-resistant insulation.

PHASE DIAGRAM - A graphical representation of the temperature and composition limits of phase fields in an alloy system as they actually exist under the specific conditions of heating or cooling (synonymous with constitution diagram). A phase diagram may be an equilibrium diagram, an approximation to an equilibrium diagram, or a representation of metastable conditions or phases.

PHENOLIC (PLASTICS) - Phenolic laminates show Outstanding temperature resistance, dielectric strength and electrical resistance, all of wjich remain uniform to 420E or aove. Most grades also ehibit good mechanical properties, such as impact strength, also outstanding dimensional stability under loading. Phenolics have long enjoyed indusry-wide acceptance as insulators, electrrical housings circuit boards, electric motor components, seals and valves.

PHILLIPS DRIVE - The Phillips screw drive is specified by ANSI Type I Cross recess and type H in ISO documentation. The Phillips Drive recess is available in six different sizes. #0 through #5 depending on the screw size.

PHILLIPS DRIVE RECESS - A cruciform type drive recess, which was developed as a solution to several problems with slotted screws: Increased cam-out potential; precise alignment required to avoid slippage and damage to driver, fastener and adjacent surfaces; and the difficulty of driving with power tools.

PHILLIPS II - Phillips II recesses are compatible with Phillips drivers, but have a vertical rib in between the cruciform recesses that interacts with horizontal ribs on a Phillips II driver to create a stick-fit, and to provide anti cam-out properties (the ribs are trademarked as "ACR" for Anti Cam-out Ribs).

PHILLIPS PUNCH HOLDER - The special sliding tool holder for the first blow on a machine with a punch rocker.

PHILLIPS/SQUARE - The Phillips/Square screw drive, also known as the Quadrex, Pozisquare screw drive, is a combination of the Phillips and Robertson screw drives. While a standard Phillips or Robertson tool can be used, there is also a dedicated tool for it that increases the surface area between the tool and the fastener so it can handle more torque.

PHOSPHATING - (1)Forming a layer of insoluble phosphates on a metal surface. (2) Passivating an electroplated article using an agent containing phosphoric acid and/or phosphates.

PHOSPHATING - Zinc plated fasteners are dipped in a solution of acid phosphates, and catalytic agents at 200 degrees F. Adherent, porous coating makes an excellent bond for paint or oil. Phosphate coatings are available: manganese, zinc and iron.

PHOSPHATING - A chemical process for treating the surface of steel, where barely soluble metal-phosphate layers are formed on the base material. The layers created are porous, absorbent and suitable as a conversion layer for subseqent powder coating without further treatment.

PHOSPHORUS - A non-metallic substance that lowers the rate of oxidation, thereby helping resist corrosion.

PHYSICAL PROERTIES - The properties defining the basic characteristics of the material or fastener.

PI-CUT ENDS - Terms signifying a particular ring design where the ends have been cut in an angular direction from the center of the ring.

PICK-UP - Small particles or oxidized metal adhering to the surface of a mill product.

PICKLE - An acid solution used to remove oxides or other compounds from the surface of a metal by chemical or electrochemical action.

PICKLING - The process of removing oxide scale from forging by treating in a heated acid bath.

PICKLING - Removal of oxides or other compounds of the basis metal from a metal surface by chemical or electrochemical action.

PIERCE - In ring rolling, the process of providing a through hole in the center of tan upset forging using a tapered or cylindrical punch.

PIERCE - An operation to remove a slug from a formed part to create a thru hole in the part.

PIERCING - Piercing is a technique wherein a technician uses a punch and die to introduce holes, slots, or notches into the component. The tight tolerances produced by piercing allow for a cleaner cut than drilling, it is also more productive that laser cutting.

PILOT - For broaching fasteners such as type KF2 and KFE the cylinmdrical portion between the knurl and the end of the shank. This is used to pilot the knurl into the mounting hole.

PILOT HOLES - Small diameter holes which are pierced in the metal prior to enlargement by a larger punch. Also used before installation of certain types of screws.

PILOT POINT - A cylindrical point designed to facilitate the alignment and starting of such fasteners as drive screws and groove pins into holes at assembly.

PIN - A straight cylindrical or tapered fastener, with or without a head, designed to perform a semi-permanent attaching or locating function.

PIN - A tooling component used to form and/or eject a part from a cavity.

PIN - A captive post that extends from a panel.

PIN DIAMETER - This term is sometimes used to mean the same as blank diameter.

PIN LOCK TYPE DRIVING TOOL - This retention design uses a pin and spring tension method to secure sockets to an extension or adapter. it is a more secure retention method than a ball lock and is commonly used in production applications.

PINCH TRIM - Trimming excess material from a drawn part at the bottom of the stroke. Leaves drawn shell without an inside burr, but with an outside burr and a thinned edge.

PINCH-POINT - A short sharp point cone point, usually having a point angle of 45 degrees, formed by a pinching operation. This point is normally limited to diameters of 1/4 inch or smaller and is applied to metal drive screws and Type BP tapping screws.

PIPE SCREW THREAD - American Standard pipe threads are tapered 1 inch in 16 or 3/4 inch per foot. They are 60 degrees threads, of National form, with flat or rounded top and bottom.

PISTOL GRIP TOOL - Pistol grip tools are commonly used for handheld, low-torque screw driving as well as higher torque fixtured or handheld applications where a reaction device can be used to absorb the torque-reaction forces.

PIT - A small depression or cavity produced in a metal surface during electrodeposition or by corrosion.

PITCH - The distance, measured parallel to fastener axis, between corresponding points on adjacent thread forms in the same axial plane and on the same side of the axis. For single start thread the pitch and lead are equal. For multiple lead threads pitch is equal to lead divided by the number of thread starts.

PITCH - Also referred to as helix, this ring dimension is the distance between two adjacent layers of the retaining ring.

PITCH - Distance from the center of one wire to the center of the next wire

PITCH (SPRING TERM) - The distance from center to center of the wire in adjacent active coils (the recommended practice is to specify number of active coils rather than pitch).

PITCH CYLINDER - An imaginary cylinder which intersects the thread form at a diameter such that the width of the thread groove and the width of the thread ridge are equal to one another and are equal to one half the pitch.

PITCH DIAMETER - On a straight thread, the diameter of the coaxial cylinder, the surface of which would pass through the thread profiles at such points as to make the width of the groove equal to one-half of the basic pitch. On a perfect thread this occurs at the point where the widths of the thread and groove are equal.

PITCH DIAMETER - The diameter of the pitch cylinder. Pitch diameter is denoted by the symbol PD or by the symbol E.

PITCH LINE - A generator of the cylinder or cone of a screw thread specified in the definition of pitch diameter.

PITCH POINT - The position on the thread where an equal amount of distance exists between the flanks of the solid part of the thread and in the space between the threads.

PITS - Sharp depressions on the surface of raw material or fastener. This localized corrosion takes the form of cavities or pits.

PITTING CORROSION - Pitting indicates deep corrosion in localized spots on a fastener. Dirt or grease on certain portions of a fastener may block oxygen from that surface, thus impeding the passive film which protects stainless from corrosion.

PLAIN - Plain as applied to finish of fasteners is used to indicate that the fastener has had no supplementary surface treatment, such as plating, coasting, painting, etc., other than being oiled.

PLAIN END - Where the pitch remains the same throughout the spring including the end coils on a compression spring.

PLAIN POINT - The end of a fastener cut approximately flat and perpendicular to the fastener axis. These points on threaded fasteners may be slightly concave especially when the threads are rolled.

PLAIN SHEARED POINT - The end of a fastener cut approximately flat and square to the axis, without chamfer.

PLAN VIEW AREA - The area of the plan view of a forging; sometimes used to indicate the relative size of a forging.

PLANISHING - A finishing operation for the purpose of removing the trim line of forgings or of obtaining close tolerances. Usually done by rolling, pressing or hammering, hot or cold.

PLASTIC RANGE - The point at which steel under a load deforms plastically and where subsequent stress will only result in further deformation and eventually failure.

PLATING - The application of a metallic deposit on the surface of the fastener by electrolysis, impact, or other suitable means.

PLATTER - The entire mass of metal upon which the hammer performs work, including the flash, sprue, tonghold, and as many forgings as are made at one time.

PLUG - (1) A protruding portion of a die impression for forming a corresponding recess in the forging. (2) A false bottom in a die.

PLUG GAUGE - An inspection tool for checking an internally threaded part against its allowed tolerances. See Go Gauge and NO-GO Gauge.

PLUNGER ASSEMBLY - A spring-loaded device used for latching or indexing purposes.

PLUNGER GUIDE - A type of connection which delivers non-rotational tonnage to the slide, thereby absorbing thrust forces and counteracting eccentric loads. Plunger guided connections are more precise when compared to pitmen.

PMP (PREVENTATIVE MAINTENANCE PROGRAM) - A schedule that is predetermined and implemented to provide regular and required maintenance check on equipment to minimize the probability of failure and associated downtime.

PMP TRANSFER - An abbreviation for the FORMAX PLUS (Pick Move Place Transfer). This transfer moves the blank straight across between forming stations with a movement away from the face of the dies. before the transfer leaves the pickup station. The transfer moves back to the face of the dies after arrival at the delivery station. It returns to the pickup station without lifting.

PNEUMATIC DIE CUSHION - An accessory that utilizes a pneumatic pressure attachment to produce the counterforce required in the forming process. It is usually comprised of a cylinder piston, pressure [late, and other elements that are typically used with a press.

PNEUMATIC POWER SOURCE - Pneumatic tools use the compressed air systems available in most assembly plants. They offer excellent power-to-weight ratios and are usually the most economical choice for many fastening applications.

POD - A magazine of Speed fasteners contained within a strip of bonded paper tape.

POINT - The configuration of the end of the shank of a headed fastener or of each end of a headless fastener.

POINT (NAIL ANATOMY) - Sharpened end opposite the head for ease in driving.

POINT ANGLE - The include angle of the point.

POINT DIAMETERS - The diameter of the point measured at the extreme end of the fastener. It sometimes may be designated as 'Chamfer Diameter' or 'Pilot Diameter' on respective point types.

POINT GEOMETRY - The designed shape of the screw's drill point. This is in regards to self-drilling screws or as commonly called "Teks". Teks is a registered tradename name of ITW.

POINT LENGTH - The length of the pointed portion of the fastener, measured parallel to the axis of the fastener from the extreme end. It may sometimes be designated as 'Chamfer Length' or 'Pilot Length' on respective point styles.

POINT LENGTH - Point length on self-drilling screws determines the material thickness which the screw can reliably penetrate. The unthreaded portion of the point (pilot section) must be able to completely drill through the material before the threads engage. If the threads engage before drilling is complete, the fastener can bind and break.

POINT OF USE INVENTORY - Inventory that is delivered to the location where it will be consumed.

POINT RADIUS - The spherical radius on an oval or spherical point.

POINT STYLE - Setscrew point penetration as much as 15% to the total holding power. When the cone-point setscrew is used, it requires the greatest installation torque because of its deeper penetration. Oval point, which has the smallest contact area, yields the smallest increase in holding power.

POINT WINGS - Point Wings are used on some screws that fasten thicker materials, such as wood or metal. The wings enlarge the hole in the fastened material allowing the threads to pass through without contacting the fastened material. This added clearance prevents separation of the fastened material from the base metal (known as "jacking"). The wings will break away on contact with the metal before the threads engage in the metal.

POINTER - A mechanism typically mounted on either Boltmakers or Threaders that is used to cut a point on the end of a cold formed bolt blank before thread rolling.

POINTING - A secondary machine operation consisting of cutting points on fastener blanks which were not pointed during the heading operation.

POINTING - Chamfering the end of a blank before thread rolling. The point may be formed in the die or cut in the external pointer.

POISSON'S RATIO - The ratio of strain in the longitudinal to that in the transverse direction. Typical values range from 0.28 to 0.33 for most forging alloys.

POKA-YOKE (MISTAKE-PROOFING) - A means of providing a visual or audible signal to indicate a characteristic state. Often referred to as "error-proofing", Poka-Yoke is actually the first step in truly error-proofing a system. A system which ensures quality in products through inspection, detection, and correction of defects as they occur.

POLARIZATION - The change in the potential of an electrode during electrolysis, such that the potential of an anode always becomes more noble and that of a cathode less noble than their respective static potentials. Equal to the difference between the static potential and the dynamic potential

POLISHING - The process of producing a smooth surface by rubbing with fine abrasive wheels, belts, or compounds, usually at a high speed.

POLYDRIVE - The Polydrive screw drive, also known as RIBE is spline-shaped with rounded ends in the fastener head. The tool has six flat teeth at equal spacing; the sizes are determined by the diameter of the star points. Its primary advantage over older screw drives is that it resists cam-out. It is used primarily in high-torque applications.

POLYETHYLENE (PE) (PLASTICS) - Because of it's flexibilty at low temperatures, excellent electrical resistance and low dielectric constant,Polyenthylene is unique. PE's also make it ideal for applications such as rollers, skids and other end-users. PE is available in a wide range of densities and formulations.

POLYPROYLENE (PP) (PLASTICS) - This natural has good impact resistance and structural rigidity. It is unaffected by any solvnet at room-temperatures. It has excellent insulating properties and is extremely lightweight. Its high fatigue strength makes it a top choice under cyclic loading conditions.

POLYSTYRENE (PS) (PLASTICS) - Is naturally clear. It exhibits excellent chemical resistance and is more resistant to irradiation than is PE or PP. Electrical resistance is also good. This, plus the ease with PS can be painted or shielded, has led to extensive eletrical and electronic applications. PS is also often used in appliances and housings. Special high gloss and high impact grades are also widely available.

POLYSULFONE (PSO) (PLASTICS) - Is a naturally transparent, true engineering plastic whose electrical and mechanical properties are constant up to temperatures above 320F. It is also rated for continuos service in steam to 300F. It shows excellent resistance to alkalies, acids and salts, as well as to manny hydrocarbons. PSO is suited for microwave use, and may also be plated or glass-filled. Amongest its many varied uses are many medical, automotive, and electronic applications.

POOCHING - Pooching is a term sometimes used to describe the effect of the area immediately surrounding a tapped hole being raised up because of the tension from the stud. Tapped holes are often bored out for the first couple of threads to eliminate this problem.

PORE (IN A COATING) - Essentially circular micro-discontinuity in the surface extending through to the underlying coating or to the basis metal.

POSITIVE STOP - A visual indication that the proper depth of penetration of the knurled ring has occurred or when the "head" is in contact with the top surface of the panel. Synoym: Shoulder

POST-INSTALLED ANCHOR - Either a mechanical or adhesive anchor installed in a pre-drilled hole in the base material

POWDER COATING - Powder coating is a dry finishing coating representing over 15% of the total industrial finishing market. Companies use poweder coatings for a high-quality, durable finish, allowing for maximized production improved efficiencies, and simplified environmental compliance. Used as protective and decorative finishes, poweder coatings are available in an almost limitless range of colors and textures.

POWDER FORGING - The plastic deformation of a powder metallurgy compact or preform into a fully dense finished shape by using compressive force; usually done hot and with closed dies.

POWDER METAL - Creating a shape by placing a powered metal into a shaped cylindrical cavity and squeezing along the top and bottom of the cylinder. The part must be carefully removed from the cylinder at which point it is said to be in the 'green state.' The part then gets sintered to fuse the powder granules together. Powered metal parts are porous and less dense than standard metal parts. If these will later be plated, they need to be resin impregnated to seal the pores (this is done by introducing a plastic filled filter with the part in a vacuum environment).

POWER ROLLS - Power-driven rolls used in pre-forming bar or billet stock that have shaped contours and notches for introduction of the work.

POWER-DRIVEN HAMMER - A forging hammer with a steam or air cylinder for raising the ram and augmenting its downward blow.

POZIDRIV - Pozidriv is an improved version of the Phillips screw drive. It was designed to allow more torque to be applied and greater engagement than Phillips drives. Thus it is less likely to cam out. Pozidriv is available in six sizes. While a Philliups screwdriver has slightly tapered flanks, a pointed tip and rounded corners, a Pozdriv screwdriver has parallel flanks, a blunt tip, and additional small ribs at 45 degrees to the main slots.

PRE-APPLIED PROCESSES - Threadlockers, Sealants, Masking, Lubricants and Assembly Aids.

PRE-BULBED - The practice of starting the bulb during the manufacture of the insert. This is done to reduce the installation or upset load required. The major disadvantage of this practice is that it requires a larger mounting hole to clear the bulb. Unless a positioning step is provided underthe head, the installed insert may not be concentric to the mounting hole.

PRE-PIERCE - (1) In ring rolling, a vertically mounted piercing (punching) tool used for preparation of ring blanks on the ring blank press. (2) A tapered tool of various diameters and lengths.

PRECIPITATION HARDENING - Hardening caused by the precipitation of a constituent from a supersaturated solid solution See also age hardening.

PRECIPITATION HARDENING - This process (also known as age hardening) holds the metal part at an elevated temperature without quenching. This increases yield strength of malleable materials, including most alloys of aluminum, magnesium, nickel, titanium, and some stainless steels. In superalloys, it improves high-temperature strength.

PRECISE COMPONENTS OF TOOLING - Tools that are utilized in the manufacture of industry-specific items; for example, automotive parts to meet requisite high-quality and cost standards.

PRECISION FASTENERS - Fasteners manufactured to close dimensional and geometric tolerances.

PRECISION FORGING - A forging produced to closer tolerances than normally considered standard by the industry.

PREFORM - (1) The forging operation in which stock is preformed or shaped to a predetermined size and contour prior to subsequent die forging operations, When a preform operation is required, it will precede a forging operation and will be performed in conjunction with the forging operation in the same heat. (2) Ring blanks or a specific shape for profile (contour) ring rolling. (3) The initially pressed powder metallurgy compact to be subjected to repressing

PREFORM - To establish a preliminary shape suitable for forming into the final part dimensions.

PREFORM IMPRESSION - Anyone or a combination of preliminary die impressions used in producing a preform Also known as blocker, buster, scalebreak, and extrusion.

PREHEATING - (1) A preliminary heating of ingots, billets, or forgings to reduce the hazards of thermal shock upon subsequent heating to higher temperatures. (2) A high-temperature soaking treatment used to change the metallurgical structure in preparation for a subsequent operation, usually applied to the ingot.

PREHEATING - Heating to an appropriate temperature immediately prior to austenitizing when hardening high-hardenability constructional steels, many of the tool steels, and heavy sections.

PRELOAD - The force developed in a bolt during tightening that, in a theoretical joint, is equal to the initial clamping force that holds the joint together. Preload and residual clamping force can differ after relaxation, embedment, and other elastic interactions have occurred in the joint.

PRELOAD - The tensile force in a bolt and the equivalent compressive force in the joint members when there is no applied load.

PREPARATION CHARGE - A one-time charge covering the cost of sinking dies and preparing required auxiliary tooling for producing forgings to a particular design. In usual practice, this charge conveys to the customer the exclusive right to purchase forgings produced on this tooling. The dies themselves are the property of the forger, who also has the responsibility for maintaining and replacing the dies as required for satisfactory production of forgings.

PRESET - Presetting, also referred to as prestressing, is an optional condition of Belleville Springs where they are coaxed flat before yielding to their design height. After presetting, the material does not return to its original state. The effects of this process increase cycle life and performance of the part.

PRESET OR REMOVE SET (SPRING TERM) - Full compression of a spring to solid state by manufacturer when needed to prevent length loss in operation.

PRESS - A machine tool with a stationary bed and a slide or ram that has reciprocating motion at right angles to the bed surface; the ram is guided in the frame of the machine.

PRESS CAPACITY - The rated force a press is designed to exert at a predetermined distance above the bottom of the stroke of the ram.

PRESS FIT - See Interference Fit

PRESS FORGING - The shaping of metal between dies on a mechanical or hydraulic press. The action is that of kneading the metal by relatively slow application of force as compared with the action of hammering.

PRESS QUENCHING - A quench in which hot dies are pressed and aligned with a part before the quenching process begins. Then the part is placed in contact with a quenching medium in a controlled manner. This process avoids part distortion.

PRESSURE PROFILE - A tabulation of the change in pressures across a forging section, usually in graphical form.

PRESSURE SENSITIVE ADHESIVES (PSA) - (PSAs) adhere to a substrate when light pressure is applied and are tacky at room temperature.

PRESTRESSING - (Also known as Scragging, or Removing Set) The process of raising the elastic limit of a spring by subjecting it to a stress greater than that to which it is subjected under working conditions and higher than the elastic limit of the material. The plastically deformed state resulting from this stress causes a beneficial redistribution of the stresses within the spring.

PRETENSIONED JOINT - A joint that resists the shear load by shear bearing on the bolts; but has been preloaded for other reasons beside slip resistance. Considered a Bearing-Type joint.

PREVAILING "OFF" TORQUE - The torque readings taken as the part is backed off during the first 360 degree of rotation. This is after clamp load has been reduced to zero.

PREVAILING ''OFF'' TORQUE - The torque readings taken as the part is backed off during the first "360" of rotation. This is after clamp load has been reduced to zero. NYLOK

PREVAILING TORQUE - The torque necessary to rotate the nut on its mating externally threaded fastener. It is measured while the nut is in motion and before any axial load is developed in the externally threaded fastener.

PREVAILING TORQUE - Unique to self-locking fasteners or components. A measure of the inherent ability of a part to produce frictional resistance to rotation in a mating thread form. Exists independent of clamp load, inclusive of both installation and removal torque.

PREVAILING TORQUE (RUNNING TORQUE) - An average measure of frictional resistance produced during rotation in either the installation or removal cycle. It is indepedent of clamp load. This is unique to self-locking fasteners and components.

PREVAILING TORQUE OR RUNNING TORQUE - The torque required to overcome kinetic friction of the mating threads plus the torque required to overcome the locking feature when 100 percent of the locking feature is engaged and the fastener is unseated. This torque can be measured in either a loosening or a tightening direction while the mating threads are in relative motion.

PRIMARY CURRENT DISTRIBUTION - The distribution of the current over the surface of an electrode in the absence of polarization.

PROCESS ANNEALING - Heating a ferrous alloy to a temperature close to, but below, the lower limit of the transformation range and then cooling, in order, to soften the alloy for further cold working.

PROFILE (CONTOUR) ROLLING - In ring rolling a process to produce seamless rolled rings with a predesigned shape either on the outside or the inside diameter, requiring less volume of material and less machining to produce finished parts.

PROGRESSIVE DIE STAMPING - Progressive die stamping occurs via a series of stamping stations. Each step in the stamping process performs a different action that alters the shape of the component being stamped. Progressive die stamping operations are long-lasting because the dies are unlikely to become damaged, the process is easy to repeat.

PROGRESSIVE DIES - Two or more die stations which are arranged in a line to perform several operations on a part, with a single operation typically undertaken at each location.

PROGRESSIVE STAMPING - Is a metalworking method that can encompass punching, coining, bending and several other ways to modifying metal raw material, combined with an automatic feeding system.

PROGRESSIVE TOOL - Die using multiple stations or operations to produce a variety of options. Can incorporate piercing, forming, extruding and drawing, and is usually applied to high quantity production runs.

PROGRESSIVES - A collection of sample forgings taken following the first and subsequent blows of the forging sequence. Also know as Progression

PROLONGATION - An extra portion of metal added in a mutually agreeable location of a forging to permit removal and subsequent testing without destroying the forging. Generally applies to open die and some large rolled rings.

PROOF - Any reproduction of a die impression in any material.

PROOF LOAD - A specified tension load that the fastener must support without permanent deformation and represents the usable strength of a certain standard of fasteners. Proof load is an absolute value, not a maximum or minimum value. Proof loads are frequently used as design values in joint analysis and fastener selection.

PROOF LOAD (EXTERNALLY THREADED) - The tension applied load that a fastener must must withstand without any indication of permanent deformation or failure. Proof load is typically calculated at 90-93 percent of the minimum yield strength.

PROOF LOAD (INTERNALLY THREADED) - The axially-applied load using a bolt or threaded mandrel that must be supported by a nut without indication of thread stripping or failure.

PROOF LOAD TESTING - Proof load testing entails stressing the sample with a quantified load that the sampling must withstand without measurable permanent set. The load used to stress the fastener is specific to the size and grade/property class of the sample.

PROOF TEST - Any specified test required for a fastener to indicate that it is suitable for the purpose intended.

PROPERTY CLASS - Designation of strength classes among bolts and nuts. For metric fasteners, property classes are designated by numbers where increasing numbers generally represent increasing tensile strengths. The designation symbol for bolts consists of two parts: (1) The first numeral of a two-digit symbol for the first two numerals of a three-digit symbol approximates 1/1000 of the minimum tensile strength in MPa. (2) The last numeral approximates 1/10 of the ratio expressed as a percentage between minimum yield stress and minimum tensile stress. Hence a fastener with a property class of 8.8 has a minimum tensile strength of 800 MPa and a yield stress of 0.8 x 800 = 640 MPa. The designation system for metric nuts is a single or double-digit symbol. The numerals approximate 1/100 of the minimum tensile strength in MPa. For example, a nut of property class 8 has a minimum tensile strength of 800 MPa. A bolt or screw of a particular property class should be assembled with the equivalent or higher property class of nut to ensure that thread stripping does not occur.

PROPRIETARY HEAD DRIVES - Proprietary Head Drives are considered tamper-resistant fasteners and usually manufactured by only a few companies. These custom designed heads which require a matching driver only from the manufacturer and only supplied to registered owners, similar to keyed locks. Slot-Lok, Avsafe, Key-Rex®, Stykfit®-7 are a few of these Proprietary Head designs.

PROTOTYPE - First part of a design which is mad to test tolerance capability, tooling concepts and manufacturing ability.

PRYING - The amplification of an external force acting on a bolt by a lever action which can occur when that force is an eccentric tensile load.

PSI - Pounds per square inch; a unit of measurement for pressure or stress. One PSI is equal to one pound of force distributed over one square inch. It is common to specify material strengths in the English system in units of PSI.

PTFE (Polytetrafluorethylene) - A polymer with a low friction coefficient. Sometimes used as a lubricant. Trade name Teflon®

PTFE (POLYTETRAFLUOROETHENE(PTFE) (PLASTICS) - An extremely low coefficient of friction makes Polytetrafluoroethylene the ideal choice where surface wear might otherwise be a problem. PTFE also exhibits a useful service life from below -100F, to temperature over 500F. It resistance to solvents is also excellent throught out a wide range of temperatures. Its low dielectric constant and electric resistance also remain constant throughout this range.

PTFE FLUOROPOLYMER - PTFE fluoropolymer coated bolts after exposure to corrosive environments can be removed with hand tools. The easy on/easy off properties exhibited by these fasteners provide safe has been demonstrated after Salt Spray corrosion testing up to 4,000 hours. The advantage is lower plant maintenance costs and increase safety using PTFE fluoropolymer coated fasteners.

PULL DOWN - Area of material next to the penetrating edge of a piercing punch, or die edge of the blanking station, where the materials yields, i.e. flows in the direction of the applied force, creating a rounded edge.

PULL GROOVES - A set of grooves on a rivet or lock bolt stem to enhance the grip of the tool when pulling.

PULL OUT - (1) The distance the TKO lever moves away from the face of the dies during the untimed portion of the TKO stroke. (2) The distance the part is permitted to pull out of the die during the first portion of the T.K.O. stroke

PULL SYSTEM - A manufacturing planning system based on the communication of actual real-time needs from downstream operations. A pull system is in contrast with Push Systems, which schedule operations according to theoretical downstream results based "best-guess" planning, MRP, or other methods.

PULL-OUT - The force required to significantly yield or fracture the insert or the panel when an axial load is applied in a pulling direction from the head side. For thin wall parts the industry standrd is to support the panel with a bushing having a hole diameter of three times the fastener shank diameter. If the panel strength is adequate, the mode of failure is shear of the bulb.

PULL-THROUGH - The resistance of a fastener to a force applied in the same direction to which it was installed.

PULLING FORCE - The axial force the tool applies during the installation of fasteners.

PUMPING OUT - A condition where blanks or die inserts are forced out of place prematurely due to hydraulic action.

PUNCH - A movable insert, either solid or hollow, which applies an installation force to the top of the fastener.

PUNCH - A tooling component typically mounted on the moving side of the tooling.

PUNCH BLOCK - A metal prop inserted between opposing tools or press members to support the weight of the slide and upper die. Die blocks are typically used as a safety measure when repairing or maintaining the press. The blocks arrest the movement of the upper die in the event that the brake or counterbalance should fail. Also known as die block or safety blocks.

PUNCH HOLDER - A part that contains the top die and serves to provide rigidity. The top die is typically mounted in the punch holder.

PUNCH PRESS - Machine supplying compression force for reshaping materials.

PUNCH ROCKER - An oscillating mechanism mounted on the front of the heading slide of single die-two blow or two die-three blow forming machines. The tooling is mounted onto the punch rocker. Between forming blows, the mechanism moves the next forming punch on center with the die.

PUNCH SIDE - Opposite side from burr side for pierced features; side on which punch enters the material.

PUNCH/INSTALLATION PUNCH - On installation tooling that member of the tooling which moves when the press cycles.

PUNCHED MOUNTING HOLE - A pierced hole requiring applied load to a punch to shear panel material through a die.

PUNCHING - The process of trimming or removing material with dies in a press.

PUNCHING - Similar to blanking, punching is the process of removing parts of a blank to further refine it. Instead of cutting new blanks out of a sheet of material, punching removes parts of a component that will be scrapped.

PUNCHING DAMPERS - Short stroke hydraulic cylinders which are systematically organized and designed to reduce shock and absorb the increased tonnage load during punching operations.

PUNCHOUT - Metal removed when punching a hole in a forging.

PUSH-OUT - The resistance of a self-clinching feature to axial loading. Push-out is conducted in the direction opposite the direction of installation of a self-clinching fastener.

PUSHER - A pin or rod that pushes the cutoff blank out of the cutter insert and into the transfer fingers.

PVC (PLASTICS) - Polyvinylchloride exhibits little or not water absorption. Since it is chlorinated, PVC also possesses natural flame retardant qualities. PVS's are available in wide variety of colors and varying compositions. They are typically employed in packaging, water and chemical piping assemblies, appliances, fuirniture and other components.

PVD - An abbreviation of (Physical Vapor Deposition). This process is used to add a wear resistant coating to some tooling components. Commonly referred to as the COLD process.

PYROMETER - A device for measuring temperatures above range of liquid thermometers.

PYROMETER - A device for measuring temperatures above range of liquid thermometers.