Drawing is a metal forming process where a starting blank, wire, rod, or tube is pulled through a converging die orifice to reduce its cross-sectional area.
Drawing is a metal forming process where a starting blank, wire, rod, or tube is pulled through a converging die orifice to reduce its cross-sectional area. Conducted primarily at room temperature (cold drawing), this process produces precise dimensional tolerances, high-quality surface finishes, and enhanced mechanical properties due to strain hardening.
The mechanical configuration and kinematics of drawing machinery are classified into linear benches and rotary continuous capstan systems, governed by workpiece stiffness and dimensions.
Linear Drawing Benches: Used for straight rods, profiles, and large-diameter tubes (lengths from 3 to 30 m) that cannot be coiled. The design features a heavy steel bed housing the die holder plate. A carriage equipped with heavy-duty serrated jaws grips the pre-pointed end of the workpiece. The carriage is driven along the linear axis by hydraulic cylinders or heavy-duty leaf chains. Kinematically, the process is single-axis, operating at drawing speeds of to .
Bull Blocks (Single-Draft Rotary Machines): Used for medium-diameter wires and heavy-gauge bars that can be coiled. The drawing force is generated by a rotating capstan (drum) that pulls the wire through the die and coils it on its external surface.
Continuous Multi-Die Drawing Machines: For mass production of wire, multiple dies and capstans are arranged in series:
The drawing die dictates material flow and surface finish. It consists of a hard, wear-resistant inner core shrink-fitted into a structural steel or brass casing.
The internal profile of a drawing die is divided into five distinct zones:
| Category | Formative Manufacturing |
|---|---|
| Library | CNC machining |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert