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The eBearing Glossary of Bearing Industry Terms
Definitions and Illustrations
P
Pear Skin
Industry jargon.
The "fuzzy" appearance on the load-bearing surface
of bearing races. Caused by contamination trapped
between the races and the rolling elements.
Pearlite
A ferrite and cementite metastable lamellar aggregate which results from the
transformation of austenite at a temperature above the bainite range.
Pfund Hardness Number
A reference standard for the hardness of a coating on a material.
A measurement of the indentation created in a coating when a
standardized round-tip quartz or sapphire stylus is applied
under a specific pressure.
Pickling
The removal of surface oxides by chemical bath or electrochemical reaction.
Pierce, Winslow S., Jr.
Developed and later patented, in 1924, a superior system for producing precision split
ball bearing inner races without loss of material.
Mr. Pierce later went on to develop the miniature ball bearings used in the Norden bombsight,
critical to the allied air war effort during World War II.
Plastic Deformation
See also Elastic Deformation.
The permanent deformation of a material when stress is applied. For plastic deformation to occur,
the material must be stressed beyond its elastic limit.
Powder Metallurgy
The use of metal powders under heat and pressure to produce shaped objects in a cavity as an
alternative to machining or other metalforming options. Powder metal parts are most often
net or near-net shapes.
A common application of powder metal parts in the bearing industry is for
clutch release bearing sleeves.
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