Definitions /Dictionary/Glossary - nptel

Shear: Engineering term referring to force normally applied to the surface of a given material.
The movement between plies of a laminate is referred to as interlaminate shear.
Shear Edge: Cut-off edge of the mold.
Sheet Molding Compound (SMC): Composite of fibers, usually polyester resin, pigments,
fillers and other additives, that have been compounded and processed into sheet form to facilitate
handling in the molding operation.
Shelf Life: Allowable storage time before a product must be used.
Shore Hardness: A material’s resistance to indentation from a spring-loaded indenter. Higher
numbers indicate materials with greater resistance.
Shrinkage: The relative change in dimension between the length measured on the mold when it
is cold and the length of the molded object 24 hours after it has been taken out of the mold.
Single Yarn: The simplest strand of textile material suitable for weaving, knitting and other
operations.
Sink Mark: A shallow depression or dimple on the surface of an injection molded part due to its
surface collapsing from local internal shrinkage after the gate seals; an incipient short shot.
Size: Treatment applied to glass fiber that allows resin and glass to adhere to one another. Also
allows glass fiber to be conveniently handled.
Skein: A loose coil of roving or strands generally used as a Quality Control sample.
Skin Coat: It is the first layer of laminate next to the gel coat.
Slashing: Applying size to a width of warp yarns on a continuous basis.
Slink: Glass bundles thrown off the chopper or cot during chopping.
Sliver: A term describing the geometry of fibrous glass reinforcement in the forming operation.
For example, 2K37 S/2 means a configuration that makes a nominal fiber diameter in the "K"
range (3700 yards to a pound) and is split into two discrete bundles in the forming cake.
Sluffing: see Doff Collapse
SMC: see Sheet Molding Compound
Snarl: see Birdnest