Since the initial development of three dimensional printing, also known as additive manufacturing, various types of three dimensional printing and printers for building a part layer by layer have been conceived. For example, Stereolithography (SLA) produces high-resolution parts. However, parts produced using SLA typically are not durable and are also often not UV-stable and instead are typically used for proof-of-concept work. In addition to SLA, Fused Filament Fabrication (FFF) three dimensional printers are also used to build parts by depositing successive filament beads of acrylonitrile butadiene styrene (ABS), or a similar polymer. In a somewhat similar technique, “towpregs” including continuous fiber reinforced materials including a resin are deposited in a “green state”. Subsequently, the part is placed under vacuum and heated to remove entrapped air voids present in the deposited materials and fully cure the part. Another method of additive manufacturing, though not considered three-dimensional printing, includes preimpregnated (prepreg) composite construction where a part is made by cutting sheets of fabric impregnated with a resin binder into two-dimensional patterns. One or more of the individual sheets are then layered into a mold and heated to liquefy the binding resin and cure the final part. Yet another method of (non-three-dimensional printing) composite construction is filament winding which uses strands of composite (containing hundreds to thousands of individual carbon strands for example) that are wound around a custom mandrel to form a part. Filament winding is typically limited to convex shapes due to the filaments “bridging” any concave shape due to the fibers being under tension and the surrounding higher geometry supporting the fibers so that they do not fall into the underlying space.
USPTO Backgrounds
USPTO Backgrounds