McGuire Glossary of Fastener Terminology

P - 35 terms

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

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 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.

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.

PCB - Laminant fiberglass flat sheet

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.

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.

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.

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.

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.

PIN - A captive post that extends from a panel.

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

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

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

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.

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

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 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).

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.

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

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 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.

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.

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.

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.

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 - 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.

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.