Cuppy

A tendency of defective wire to prematurely break with a pencil-point type fracture. It may be caused by segregation, resulting in a hard brittle center and a more ductile ex­terior, or due to the use of dies with reductions angles that are too large, and an excessively small reduction in area, so the wire is not cold worked evenly throughout the cross-section, the outer skin being worked more than the core. This defect is often observed only at a late stage of wire production and not at the particular die that is defective. See Central Burst.