DICTIONARY

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- P -


Paddle Method (preload test) -
A method for determining fastener preload, or, more specifically, the load required to "undamp" a fastened fixture assembly and permit movement of the paddle.
Pan Head -
A protruding head with a flat top which rounds to a cylindrical outside diameter.
Panel (access) -
A panel so attached as to facilitate removal and replacement for interior inspection or repair purposes.
Passivate -
To change the chemically active surface (normally by the removal of free iron) of a material to a much less reactive state and thus inhibit corrosion.
Permeability (magnetic) -
A general term used to express various relationships between magnetic induction and magnetizing force.
Photoelastic -
An optical method for evaluating the magnitude and distribution of stresses in a given transparent or transparent film coated specimen. Variations of load will then produce variable and visible stress distribution patterns through light refraction; viewed and evaluated using polarized light.
Physical Properties -
Metallurgically, the properties, other than mechanical properties, that pertain to the physics of a material such as density, electrical conductivity, heat conductivity, thermal expansion, etc.
Pickling -
Removing surface oxides from metals by chemical or electrochemical reaction.
Pin -
A cylindrical or tapered fastening device, with or without head or threads, designed to hold parts together.Some special types are as follows:
Pintail -
Ina rivet, blind fastener, or lockbolt, an extension of the fastener which mates with a tool for pulling to effect fastener installation. The pintail breaks off after completed installation.
Pipe -
Metallurgically, an extrusion defect due to the oxidized surface of the billet flowing toward the center during the forming of rod, bar or wire.
Pitch -
The distance between corresponding points on adjacent identical features of a repetitive design or pattern.
Pitch Diameter -
In straight thread geometry, the pitch diameter is the diameter of a theoretical cylinder which intersects the thread profiles at the points where the widths of the thread and groove are equal.
Point -
Infastener configuration, the chamfered thread end of bolts which facilitates engagement with mating threads.
Poisson's Ratio -
The absolute value of the ratio of the transverse strain to the corresponding axial strain in a body subjected to uniaxial stress; usually applied to elastic conditions.
Potting -
Usually a catalyzed adhesive compound, chemically or thermally activated to solidify and bond a fastener to core material and skin of sandwich panels and provide retention of the device.
Powder Metallurgy -
The art of compacting metal powders for the production of metallic components.
Precipitation Hardening -
Preclamping -
Clamping workpieces together during hole preparation and/or prior to and during installation of fastening devices.
Preload -
The amount of residual axial clamping load remaining in the fastener system after complete installation in a workpiece.
Press -
A machine having a stationary bed and a slide or ram which has reciprocating motion at right angles to the bed surface to apply compressive loading.
Process Annealing -
Proof Load -
A predetermined load, generally some multiple of the service load, to which a component or structure is subjected before acceptance for use.
Proportional Limit -
The maximum stress at which strain remains directly proportional to stress.
Pull Grooves -
Serrations or features formed in a pull stem to improve gripping capability of jaws (collet) of a pull tool when applying an axial load to a fastener during installation.
Pull Stem -
An extension of a fastener which engages a tool capable of exerting an axial pulling force to install the fastener. The pull stem separates at a predetermined force.
Pull Tool -
A tool that exerts an axial force on a fastener extension, (i.e., a pull stem) in installation. Loads applied are normally reacted into swaging or deforming a fastener component.
Push Out -
A test criterion applying to the resistance of a fastener to displacement when a specified axial load is exerted in the direction opposite normal loading.


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