Your guide to additive manufacturing

The technology allows for the production of complex structures and shapes that would be difficult or impossible using traditional manufacturing methods such as injection moulding.

Scott Bader focuses on vat polymerisation technologies. In vat polymerisation, a liquid photosensitive resin is placed into a printer’s vat or tank. A file, which has been digitally sliced into layers beforehand, relays to the printer the dimensions of each layer, which upon selectively exposing the resin surface to light creates the shape. The build platform to which the cured layer is attached to then moves up, raising the cured section and exposing new layers of resin to be cured, until the final part has been produced

Types

Within vat polymerisation, there are 3 main methods of additive manufacturing:

• Stereolithography (SLA) which uses a laser to trace each layer of the model, curing the resin along its path

• Digital Light Processing (DLP) which utilises a digital projector to expose the resin to a complete image of each layer in order to initiate curing

• Liquid Crystal Display (LCD) which functions similarly to DLP, but utilises an LCD screen to mask the UV light and display the layer shape desired

Comparisons

SLA resins are often incompatible with DLP and LCD printers due to the light spectrum at which the laser operates. SLA machines tend to have restrictions on the materials that they can use, rendering the majority “closed” systems.

In comparison, DLP and LCD machines tend to be “open systems” where supplier or third party resins are compatible. The resins are also interchangeable, as most DLP and LCD printers operate on 385-405nm wavelengths, although the optimum settings may differ. Given the advantages of print speed with good resolution, both are highly suited for rapid prototyping and small scale manufacturing.

DLP is more commonly used in professional fields where the improved precision and availability of larger machines is desired. In comparison, hobbyists and beginners to 3D printing favour desktop LCD printers due to the lower cost and smaller footprint.