Terminology

Abrasion

the surface loss of material due to frictional forces.

Abrasion Resistance

the resistance of a material to loss of surface particle due to frictional forces.

Blister

a cavity or sac that deforms the surface of a material.

Cell

a single small cavity surrounded partially or completely by walls.

Cellular Material

a generic term for materials containing many cells (either open, closed or both) dispersed throughout the mass.

Cellular Rubbers

a cellular material made of rubber. Cellular rubber products all contain cells or small hollow receptacles. The cells may either be open or interconnecting, or closed and not interconnecting.

Closed Cell

a cell totally enclosed by its walls and hence not interconnecting with other cells.

Collapse

inadvertent densification of a cellular material during its manufacture resulting from breakdown of its cellular structure.

Compound

an intimate mixture of a polymer with all the ingredients necessary for the finished article.

Compression Deflection

PSI to compress lab slab a specified percentage of overall height, normally 25%.

Compression Set

the residual deformation after removal of the force that has subjected the specimen to compression.

Crazing

a surface effect on rubber articles characterized by many minute cracks.

Cure

the act of vulcanization. See vulcanization.

Cooling Time 
The elapsed time required for the melt to reach its Vicat softening temperature.

Cycle 
Complete, repeating sequence of operations for injection molding a part. 

Cycle Time 
In a molding operation, cycle time is the time elapsing between a particular point in one cycle and the same point in the next cycle.

Durometer

an instrument for measuring the hardness of vulcanized rubber or plastic. Shore 00 scale is for sponge, Shore A for dense/solid.

Durometer Hardness

an arbitrary numbering scale that indicates the resistance to indentor point of the durometer. High values indicate harder materials.

Expanded Rubber

Cellular Rubber having closed cells made from a solid rubber Compound.

Edge Gate 
Entrance to the part from the runner located on the parting line.

Ejector Pin 
A rod, pin or sleeve which pushes a molding off of a core or out of a cavity of a mold.

Flash 
Resin that is forced out of the mold cavity area and onto the parting line or into the vents of the mold. A very thin film of cured resin attached to the molded part.material.

Flashpoint
The temperature at which solvents volatilize sufficiently to produce a flammable mixture.

Foaming Agent
Any substance which alone or in combination with other substances is capable or producing a cellular structure in a plastic mass.

Forming
A general term encompassing processes in which the shape of plastic pieces such as sheets, rods or tubes is changed to a desired configuration.

Gate 
In injection molding, the channel through which the molten resin flows from the runner into the cavity.

Gate Blush
A blemish or disturbance in the gate area of an injection molded article.

Family Mold 
A multiple cavity mold which produces non-identical parts simultaneously.

Open Cell

a cell not totally enclosed by its walls and hence interconnecting with other cells.

Ozone Cracking

the surface cracks, checks or crazing caused by exposure to an atmosphere containing ozone.

Post Cure

heat or radiation treatment to which a cured or partially cured rubber is subjected to enhance one or more properties.

Rebound

a measure of the resilience, usually as the percentage of vertical return of a body that has fallen and bounced.

Rubber

a material that is capable of recovering from large deformations quickly and forcibly, and can be, or already is, modified to a state in which it is essentially insoluble (but can swell) in boiling solvent, such as benzene, methyl ethyl, ketone and ethanol-tulene isotope.

Set

strain remaining after complete release of the load producing the deformation.

Shelf Aging

the time an unvulcanized rubber stock can be stored without losing any of its processing or curing properties.

Shore Hardness

see durometer hardness.

Skin

a relatively dense layer at the surface of a cellular material.

Sponge Rubber

cellular rubber consisting predominantly of open cells made from a solid rubber compound.

Substrate

a material upon the surface of which an adhesive is applied for any purpose such as bonding or coating.

Tear Strength

the maximum load required to tear apart a specified specimen, the load acting substantially parallel to the major axis of the test specimen.

Tensile Strength

the maximum tensile stress applied during stretching a specimen to rupture.

Vulcanizate

preferably used to denote the product of vulcanization, without reference to its shape or form.

Vulcanization

an irreversible process during which a rubber compound through a change in its chemical structure (for example: cross-linking) becomes less plastic and more resistant to swelling by organic liquids and elastic properties are conferred, improved, or extended over a greater range of temperature.

Weathering

the surface deterioration of a rubber article during outdoor exposure, such as checking, cracking, crazing or chalking.