Z Corporations’ printers use a powder as the basis for the things it builds. The powder is laid down in a thin layer. When the printer head passes over it, the nozzle sprays out a glue-like substance instead of ink. The bed on which the powder is laid then moves down 4/10000ths of an inch, another layer of powder is put down and the process repeats. Making a small part can take a few hours – and the current generation of 3-D printers can produce parts up to about 640 cubic inches, somewhat bigger than a basketball.
The advantage to Z Corp.’s method – and other systems that use powder – is that hollow spaces can exist in the model, saving on material. The powder also acts as a support. The downside is that the model isn’t as strong, unless you dip it into a resin, which soaks into the tiny pores on the surface.
Harmon says that, besides industry, there is a market for making one-off models that Z Corp serves. One big application: wedding-cake toppers.
Other companies, notably Dimension in Eden Prairie, Minn., make machines that use plastic. The machine works in a similar fashion, laying down plastic layer by layer. The difference is that the print head alternates between the plastic used in the model and a support material, which helps keep the shape for overhangs and hollow forms. The supporting material can be chipped off the finished models.
An Israeli company, Objet, has a version that can make a wider variety of shapes and uses a resin. As each layer prints, the resin is dried and cured with an ultraviolet lamp.