What are the differences between seamless and structural aluminum extrusions?

seamless and structural extrusion

What is extrusion?

Extrusion is a method of producing objects with a fixed cross-sectional profile. A hot work tool steel die is machined with the desired hollow or solid profile. Then, in an extrusion press, a heated aluminum billet is forced through the die, resulting in a linear piece of aluminum in the shape of the profile cross-section.

The flexibility of the extrusion process, which allows for a wide range of shapes, is one of its many advantages. Brittle materials can also be worked with by extrusion manufacturers because the only forces applied to the workpiece are compressive and shear stresses.

Although they are similar, extrusion and drawing differ in that the material is pulled rather than pushed through the die, limiting the process to simpler shapes than extrusion. If there is enough material to push through, an extrusion can theoretically be infinitely long. Extrusions are typically limited in length due to the manner in which they will be transported.

What is a seamless extrusion?

Seamless extrusion is one of the most common methods of extrusion. This entails a fully extruded hollow tube with no welding or bracketing running the entire length of the profile. The process of producing a seamless aluminum tube is known as piercing extrusion. Starting with a solid round aluminum billet as raw material, it is heated to the desired temperature before being punched with a small hole at one end to serve as the starting point.

The main advantage of the seamless extrusion process is the absence of a welded seam, which is the mechanically weakest point of the profile’s structure.

As a result, the finished product has greater structural integrity and is more resistant to failures along weld lines; seamless extrusions are the preferred material for pressure vessels. A seamless tube is also ideal for anodizing and other finishing procedures.

What is structural extrusion?

In contrast to a seamless extrusion, a structural extrusion is intended to be joined to another extruded part using welding, a bracket, or some other type of fastener. This means that, regardless of how strong the extruded material is, the weld point or connector holding the pieces together will be the extrusion’s weak point.

Hollow-profile structural extrusions such as tubes are formed using a porthole or bridge die method. Similar to a seamless extrusion, the aluminum billet is forced through the die with tremendous force at high temperatures. The profile wall must be repressed within the die because it will separate during the extrusion process. This occurs as the material is extruded through the extrusion die in the extrusion press.

When finished or anodized, extruded pipes can be distinguished from seamless products by having a seam that is visible and separate from any die lines.

One advantage of extrusion is greater control over the eccentricity of the wall thickness. Multi-hole dies can also be used, allowing for smaller profile sizes. Structural extrusions are also less expensive and faster to produce.

T-slots, angles, tracks, fasteners, and brackets are all used to connect structural extrusions. Panels, wire mesh, or screens can be attached to aluminium frames. The industry has advanced to the point where these extrusions can be purchased in kits and assembled quickly. Manufacturing, retail, automotive, and medical industries are examples of typical use cases. Applications include office workstations, machine bases, enclosures, industrial racking, fixtures, safety guards, stairs, platforms, and material handling carts.



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