Metal Forming Extrusion Key Terms

Get acquainted with common terminology associated with metal forming extrusion

By Howard Robertson

Metal forming extrusion is the process of fabricating parts by squeezing the metal through a high pressure vent. If you want to use metal forming extrusion for your applications, you will need to be conversant with the technical terms related to metal forming extrusion and the different types of extrusion processes and their various characteristics.

This guide covers some of the key terms of metal forming extrusion, such as hot or cold extrusion, direct or indirect extrusion, extrusion speed and co-extrusion.

Hot extrusion

As the name indicates, hot extrusion is carried out at high temperatures. At higher temperatures, the yield strength of a metal or alloy is less than its value at room temperature. This is a very economical process, since the dies used are inexpensive and interchangeable.
Try: You can read through the explanation for hot extrusion process at GlobalSpec, an online information resource.

Cold extrusion

Unlike hot extrusion, this process is carried out at room temperature. However, extrusion at room temperature might induce some stresses in the extruded product.
Try: You can read through the description of the cold extrusion process at Heckler AG, a metal forming company.

Direct extrusion (also known as forward extrusion)

In this process, a preheated billet, placed in a heavy walled container, is pushed through the die by ram pressure. The metal flows in the same direction as the ram has traveled.
Try: You can read through information about direct extrusion at Mid-States Aluminum Corp. (PDF), an aluminum manufacturer.

Indirect extrusion

In indirect extrusion, the die is at the ram end of the billet and the product travels through the hollow ram and in the opposite direction.
Try: For information about indirect extrusion, you can read through the glossary of technical terms at Capital Aluminium Extrusions Limited.

Hydrostatic extrusion

In this extrusion process, pressurized liquid surrounds the billet completely, except where the billet is in contact with the die.
Try: You can read through the information about the hydrostatic extrusion process at Extruded Profile, a business-to-business marketplace for extrusion products.

Co-extrusion (also known as cable sheathing)

Co-extrusion refers to extrusion of two materials simultaneously from a single die. This is done in such a way that the two separate materials fuse together to form a single structure.
Try: For information about the co-extrusion process, you can read through the technical glossaries at Bloomer Plastics, Inc. and Shanghai Jari Extrusion Technology Co. Ltd.

Extrusion speed

Extrusion speed is an important specification of any extrusion process. Extrusion speed affects the properties of extruded products.
Try: Burak Aluminium offers a glossary of technical terms, such as hollow dies, solid dies and extrusion speed.