Cold Work

Cold work is the plastic deformation of a metal below its recrystallization temperature, typically at or near room temperature. In shop practice this includes cold drawing, cold rolling, cold forging, thread rolling, swaging, crimping, staking, and metal spinning. It raises strength and hardness through work hardening while reducing ductility, so cold-worked bar stock behaves differently from hot-worked material.

On the shop floor, incoming bar stock and blanks often arrive already cold worked from the mill. That means the material is harder, stronger, and less ductile than hot-rolled stock, with a better surface finish. When programming a CNC lathe or mill, the machinist must account for these elevated properties. Cutting forces run higher, tool wear accelerates, and feeds and speeds should be adjusted downward compared with annealed material. Cold-worked stock also carries residual stresses from rolling or drawing. When features are machined asymmetrically, these stresses can redistribute and move the part after roughing, affecting finish tolerances. In secondary operations such as thread rolling, swaging, or staking, the same behavior is put to use deliberately: controlled plastic deformation strengthens the part. Recognizing whether stock is cold worked or hot worked, and whether the process is machining or forming, prevents wrong material callouts and keeps dimensional control predictable.