Lubricity Lubricity refers to the load-bearing characteristics of a plastic under conditions of relative motion. Those with good lubricity tend to have a low coefficient of friction either with themselves or other materials and have no tendency to gall. Mold Shrinkage Mold shrinkage is the amount of contraction from mold cavity dimensions that a molded part exhibits after removal from the mold and cooling to room temperature. For a given material, mold shrinkage can vary with design and molding variables such as part walls thickness, flow direction, and injection molding conditions. Plasticity Plasticity is the ability of material to preserve the shape and size to which it is formed.
Plasticity occurs when the stress goes beyond yield strength on the stress-strain curve for plastic.
Increases in temperature affect plasticity of plastic materials. Toughness refers to the ability of plastic to absorb mechanical energy without fracturing. This process is done with both elastic and plastic deformation. Material toughness is often measured as the area under the stress-strain curve. As a rule, unfilled resins have excellent toughness.