Kylmäpiirustus

Kylmäpiirustus, also known as cold drawing, is a metalworking process used to shape metal by pulling it through a die at room temperature. This process is primarily used to reduce the cross-sectional area of a workpiece, such as a wire, rod, or tube, and to improve its surface finish and mechanical properties. Unlike hot working, where the metal is heated to high temperatures, cold drawing does not involve heating, hence the name "cold."

The primary benefit of cold drawing is the enhancement of the material's strength and hardness through strain hardening. As the metal is deformed at room temperature, its internal crystal structure is altered, leading to increased tensile strength and yield strength. This process also results in a smoother and more precise surface finish compared to hot working methods. Cold drawing is crucial in producing components that require tight tolerances and excellent surface quality, such as those found in the automotive, aerospace, and medical industries.

Various metals can be cold drawn, including steel, aluminum, copper, brass, and precious metals. The process involves several stages, often with intermediate annealing steps for very high reduction ratios, to prevent the metal from becoming too brittle. The die used in cold drawing is typically made of hardened steel, carbide, or diamond, depending on the material being drawn and the desired precision. The pulling force is applied by a machine called a drawbench or a draw frame.