Definitions /Dictionary/Glossary - nptel
Definitions /Dictionary/Glossary - nptel
Definitions /Dictionary/Glossary - nptel
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Shrinkage: The relative change in dimension between the length measured on the mold when it<br />
is cold and the length on the molded object 24 hours after it has been taken out of the mold.<br />
Significant: Statistically, the value of a test statistic is significant if the probability of a value at<br />
least as extreme is less than or equal to a predetermined number called the significance level of<br />
the test.<br />
Significant Digit: Any digit that is necessary to define a value or quantity.<br />
Silicon Carbide Fiber: A reinforcing fiber with high strength and modulus; density equal to that<br />
of aluminum. It is used in organic metal-matrix composites.<br />
Sink Mark: A shallow depression or dimple on the surface of an injection molded part due to<br />
collapsing of the surface following local internal shrinkage after the gate seals; an incipient short<br />
shot.<br />
Sisal: A white fiber produced from the leaves of the agave plant. Used as a reinforcing filler, in<br />
short chopped lengths, to impart moderate impact resistance.<br />
Size System: See Finish.<br />
Sizing: A generic term for compounds which are applied to yarns to bind the fiber together and<br />
stiffen the yarn to provide abrasion-resistance during weaving. Starch, gelatin, oil, wax, and<br />
man-made polymers such as polyvinyl alcohol, polystyrene, poly-acrylic acid, and polyacetatates<br />
are employed.<br />
Skewness: See Positively Skewed, Negatively Skewed.<br />
Skein: A continuous filament, strand, yarn, roving, etc., wound up to some measurable length,<br />
and usually used to measure various physical properties.<br />
Skin: A layer of relatively dense material used in sandwich construction on the surface of the<br />
core.<br />
Skin Coat: The first layer of laminate next to the gel coat, generally one ply of chopped strand<br />
mat.<br />
Slave Pump: A catalyst pump, which is driven by the resin pump through a pair of level arms.<br />
Sleeving: It is a common name for tubular braided fabric.<br />
Slenderness Ratio: The unsupported effective length of a uniform column divided by the least<br />
radius of gyration of the cross-sectional area.<br />
Sliver: A continuous strand of loosely assembled fiber that is approximately uniform in crosssectional<br />
area and has no twist.