Mixing Technologies in the 3D Printing Industry
The 3D printing industry has revolutionized the way we design and manufacture a wide range of products – from aerospace components and tooling parts, dental and medical devices, batteries, toys, wearables, food, and even housing structures. In this article, we refer to “3D printing” and the broader term “additive manufacturing” interchangeably. Additive manufacturing is the creation of objects by “adding” material — as opposed to removing material, like in the traditional processes of CNC machining (drilling, boring, milling, reaming), laser cutting and water jet cutting (collectively known as “subtractive manufacturing”).
The raw materials, aka feedstock, of 3D printers come in various forms including filaments, wires, rods, pellets, liquids, slurries, pastes, gels, and powders. The material itself could be a plastic, elastomer, composite, metal, alloy, or ceramic.
Examples of plastic feedstocks are acrylonitrile butadiene styrene (ABS), polylactic acid, polyamide, polycarbonate, polyethylene terephthalate (PET), polypropylene, polystyrene, polyvinyl alcohol, and other high-performance polymers (such as PEEK, PEKK, PEI and PVDF).
For applications requiring rubber-like properties, thermoplastic polyurethane, thermoplastic co-polyester, silicone resin, liquid silicone rubber, and other elastomers are used.
Composites could be a plastic or elastomer that is reinforced with glass fiber, carbon fiber/ nanotubes, Kevlar, graphite, graphene, metal, ceramic powders – basically any fillers or additives that increase strength, conductivity, thermal stability, rigidity/flexibility, shock resistance and other desired properties.
Metal additive manufacturing utilizes stainless steels; tool steels; refractory metals (molybdenum, niobium, tantalum, tungsten, rhenium); precious metal alloys (platinum, rhodium, iridium, palladium, silver, gold); titanium alloys; aluminum; and specialty alloys (Inconel, cobalt chrome).
Technical ceramics withstand high levels of heat without breaking or warping, making them ideal for high- temperature applications. Examples include aluminum oxide (alumina), zirconium oxide (zirconia), silica, aluminum nitride, boron carbide, silicon carbide and silicon nitride. Sand, concrete and clay are also ceramic materials used in additive manufacturing. Another type is bioceramics, a subclass of ceramics possessing excellent biocompatibility and bioactivity potential. Bioceramics are used in dental implants, bone grafts and scaffolds that are not only non-toxic but also actively help the body repair itself. Bioactive glasses, hydroxyapatite and tricalcium phosphate fall under this niche category.
All the above options are narrowed down by the performance requirements and choice of 3D printing process. There are many techniques and equipment available today including fused deposition modeling, stereolithography, selective laser sintering, digital light processing, binder jetting, electron beam melting, material jetting and more.