forming

Forming is a class of manufacturing processes in which a starting workpiece is reshaped by plastic deformation into a new geometry without removing material. The mass of the part remains the same, and the process often induces work hardening and changes in grain structure. Forming differs from subtractive methods such as milling or turning, which remove material, and from casting, which relies on flow into a mold.

Forming operations are typically divided into bulk forming and sheet or strip forming. Bulk forming includes forging (open-die and closed-die), extrusion, rolling, and drawing, where the material undergoes significant deformation. Sheet forming processes include stamping, bending, deep drawing, hydroforming, and spin forming, usually on thin, wide sheets shaped with dies and punches.

Key process variables include material properties (strength, ductility, anisotropy), temperature, strain rate, lubrication, and tooling geometry. Elevated temperatures enable hot forming, reducing forces and improving ductility, while cold forming preserves dimensions. Tooling design, lubrication, and friction influence formability, and many operations require compensation for springback and dimensional changes.

Materials used include metals such as steel, aluminum, copper, and titanium, as well as polymers under suitable conditions. Forming is widely used in automotive, aerospace, construction, and consumer electronics for producing structural components, cans, tubes, housings, and other complex parts.

Advantages include high material utilization, strong finished parts, and good surface finish; limitations include high tooling costs, size and shape constraints, and defects such as wrinkling, tearing, thinning, and springback. Forming design often relies on computer simulation, empirical data, and formability tests to select processes and predict outcomes.