Abrasion Resistance
The ability of a rubber compound to withstand mechanical wear.

Air Trap
Air that is trapped in a product or mold during cure, usually causing a void in the part.

Bloom
A milky discoloration is caused by the migration of compounds on the surface of a rubber component after molding or storage.

Brittleness
The tendency of a rubber product to crack, break or snap under pressure; fragility.

Clamping Force
The amount of pressure placed on a mold to keep it closed during a molding life cycle.

Color Streaks
A rubber product defect is characterized by a variation in color or a streaking pattern in the molded component.

Compression Molding
Molding process in which a preform of rubber compound is placed directly in the mold cavity and compressed to shape by the mold.

Cycle Time
Length of time to mold one heat of parts. Load materials, close press, cure rubber, open press, and demold parts.

Deflashing
The process of removing the excess rubber material (or flash) from a molded product. Delamination A molded rubber defect is characterized by the forming of several layers of material or the appearance of separate layers on the surface of a component.

Die
A manufacturing tool is used to stamp or cut out a rubber material during compression.

Durometer
The numerical scale of rubber hardness.

Elastomer
Any natural or synthetic material with resilience or memory sufficient to return to its original shape after major on minor distortion.

Flash
Excess molding material on the surface or joints of rubber products.

Flow Marks
A manufacturing defect caused by improper flow of rubber material indicated by a wavy surface.

Hardness
The measurement of resistance to the force of a polymer component.

Mold Cavity
The hollow space of a mold where the rubber or silicone is shaped.

Mold Lubricant
Material is usually sprayed onto the mold cavity surface prior to molding, to facilitate the easy removal of the molded part.

O-Ring
A torus-shaped mechanical gasket is used to seal liquids or gases.

Overmold
A molding process that allows previously molded parts to be reinserted forming a new layer of polymer material around the first component.

Parting Line
The line on the surface of a molded part where the mold plates meet.

Rubber – Natural
Raw or crude rubber is produced from certain plants and vegetables.

Rubber – Synthetic
Manufactured or man-made elastomers.

Shrinkage
The contraction of rubber material after molding and cooling.

Silicone Molding
The manufacturing process in which silicone rubber is heated and injected through a series of runners into a mold producing pliable products such as gaskets, seals, and membranes.

Sprue
The opening in the cavity lets the rubber flow from the runner to the cavity.

Transfer Molding
A molding process in which rubber compound is placed in a pot that is part of the mold, heated, and squeezed through sprues and runners into the mold cavity.

Viscosity
The measurement of resistance to flow under stress.

Voids
The unintended absence of material in spaces within a molded part where elastomer material did not fill.

Vulcanization
The irreversible thermal process converting polymers or rubber into a more durable and resistant compound.

Warping
A defect that results in a twisted or distorted rubber product is usually caused by incorrect temperature.