BACKGROUND

Additive manufacturing techniques, such as three-dimensional (3D) printing, relate to techniques for making 3D objects, or articles, of almost any shape from a digital 3D model through additive processes in which 3D articles are generated on a layer-by-layer basis under computer control. A large variety of additive manufacturing technologies have been developed, differing in build materials, deposition techniques and processes by which the 3D article is formed from the build material. Such techniques may range from applying ultraviolet light to photopolymer resin, to melting semi-crystalline thermoplastic materials in powder form, to electron-beam melting of metal powders.

Additive manufacturing processes usually begin with a digital representation of a 3D article to be manufactured. This digital representation is virtually sliced into layers by computer software or may be provided in pre-sliced format. Each layer represents a cross-section of the desired article, and is sent to an additive manufacturing apparatus, which in some instances is known as a 3D printer, where it is built upon a previously built layer. This process is repeated until the printed article is completed, thereby building the article layer-by-layer. While some available technologies directly print material, others use a recoating process to form additional layers that can then be selectively solidified in order to create the new cross-section of the article.

The build material from which the article is manufactured may vary depending on the manufacturing technique and may comprise powder material, paste material, slurry material or liquid material. The build material is usually provided in a source container from where it may be transferred to the building area or building compartment of the additive manufacturing apparatus where the actual manufacturing takes place. For the example of powder build materials, these are fused together during the printing process. Excess, unfused powder may be recycled for use in a future printing process.

