Volumes of production

Comparable to injection molding.

Unit price vs. capital investment

The per unit cost of Exjection^® molding is comparable to that of a traditional injection molding. However, the initial investment costs are higher her because of the movable cavity.

Speed

The type of material and the wall thickness of the part define the speed of the cavity’s movement and thus the cycle time.

Surface

Comparable to the high surface finish that is available from conventional injection molding.

Types/complexity of shape

Exjection^® allows for multicavity components, which means combined components can be manufactured in one cycle. It also allows for over-molding.

Scale

Can vary widely.

Tolerances

±1/250 inch.

Relevant materials

A wide range of commodity and engineering thermoplastics have been successfully processed. The over-molding of metal and wood is also a possibility.

Typical products

The process is ideally suited to producing long, thin-walled parts, such as LED lighting strips, lamp covers, and cable ducts with integrated moldings such as closures and caps.

Similar methods

Exjection^® is a proprietary process and there are no comparable methods.

Sustainability

Exjection^® allows for several processes to be combined in one single cycle, which eliminates the need to transport parts between manufacturers, and so decreases emissions in addition to reducing lead time and therefore energy use.

Further information

www.exjection.com

Extrusion

Close-up of extrusion die.

Detail from extrusion emerging from die.

Product	Extrusions
Designer	Thomas Heatherwick
Materials	aluminum
Manufacturer	Haunch of Venison
Country	UK
Date	2009

Apart from the large scale of this piece, the most wonderful aspect is the reminder of the extrusion process in the tail. It illustrates an aspect of extrusion that is always cleaned up and never seen.

Extrusion occurs in a variety of forms, from the low-tech squeeze of a toothpaste tube and the making of foods such as long-stranded pasta, to aluminum window frames and the continuous lengths of hard-boiled egg that McDonald’s slices into its salads. In the simplest terms, extrusion is about squeezing a material through a hole in a die and producing continuous lengths of material at whatever profile that hole has.

This bench, or chair depending on the length you cut it, designed by Thomas Heatherwick shows a very large-scale example of extrusion. The project follows the simple premise of how can you make a seat, legs, and back rest from a single shape in a single materials and eliminate any connectors or additional components. Heatherwick sought the largest extrusion machine in the world in order produce his vision. The piece also required a lot of polishing in order to transform the dull aluminum into a mirror-bright surface.

The piece captures the essence of the continuous nature of the production process, showing the unfinished tail that twists into space.

–  The best way to make long strips with the same profile.

–  Can be used for a range of materials.

–  Extensive production base.

–  Parts often need to be cut to length, assembled, or drilled.