<<Back to the Previous Page <<Fundamentals <<Knowledgebase


Hot-Rolling, Cold-Forming, Extruding and Forging

In general, “rolling” is a process that uses a pair of rolls to form materials. There are two rolling techniques, hot-rolling and coldroll-forming based on the temperature of the metal being used. If the temperature is above the crystallization temperature of metal, the process is called hot-rolling; otherwise it is called cold-rolling.

In hot-rolling, hot-molten steel is passed several times through pairs of rolls to achieve the desired profile. Most structural steel components such as I-Shape, L-Shape, etc. are hot-rolled.


Cold-rolling can increase the material strength and improve the surface finish. Coldroll-forming uses thin sheets of steel to form into various shape sections such as floor and roof panels or C or Z shapes. These shapes are called cold-formed shapes.

Hot Rolling Process


Cold Forming a C-shape


Cold Forming a Pipe

Extrusion is a process to produce components by pushing or drawing the material through a die (mold) of the desired cross-section. Various materials such as aluminum, polymers, and ceramic or food stuffs can be used to manufacture extruded pieces. Using extrusion processes, components with complex cross-section can be produced. There are two methods of extrusion: hot-extrusion and cold-extrusion.

Extrusion of a Triodetic Node

Forging is a process used to form metal objects by heating and applying compression force in the form of blows using a power hammer or press. Forging improves the physical properties of metal. Iron and steel are usually hot-forged.

Forging a Steel Ball



<<Back to the Previous Page <<Fundamentals <<Knowledgebase



© 2011 Virginia Polytechnic Institute and State University