Extrusion

Process Definition & Working Principle

Extrusion is a plastic-deformation (formative) manufacturing process in which a material, in the form of a solid billet or polymer pellets, is subjected to high compressive force and compelled to flow through a shaped die orifice. This produces a continuous, elongated profile with a constant cross-section corresponding to the geometry of the die opening.

Physical Principles of Plastic Deformation in Metals

During hot metal extrusion (e.g., aluminum, copper alloys), the material is deformed under a state of triaxial hydrostatic compression. This specific stress state is highly advantageous because it suppresses the nucleation and propagation of microvoids and cracks, enabling the alloy to undergo extreme plastic strains without structural failure.

Kinematics, Axes, & Machine Configuration

Extrusion machine configurations and kinematics diverge depending on whether they process metallic alloys or polymers.

Metal Extrusion Press Configuration

Metal extruders are high-capacity, heavy-duty hydraulic presses, usually oriented horizontally. Clamping and extrusion forces range from $10\text{ MN}$ to over $150\text{ MN}$ ($1,000$ to $15,000$ metric tons). The core kinematic assembly comprises: