Part 1 of 2
by Cassandra Balentine
Materials for additive manufacturing (AM) vary from plastic filaments to metals or ceramic materials. The broad range of three-dimensional (3D) printing methods require different substances to properly function.
For this article, we look at several methods of AM processes, including binder jetting, directed energy deposition (DED), material extrusion, material jetting, powder bed fusion (PBF), sheet lamination, and vat photopolymerization. These processes utilize a variety of materials, including plastic, composite, metal, wax, sand, and ceramics.
Binder Jetting
Binder jetting is an AM process in which a printhead selectively deposits a liquid binding agent onto a thin layer of powder particles. The powdered materials include metal, sand, ceramics, or composites.
Jabil offers polyamide (PA) 12 copolymer material options for binder jetting, which are designed to provide greater stiffness, strength, and toughness over similar materials on the market. According to the company, the materials are ideal for printing items that require extra strength and stiffness.
Copolymers are generally plastic materials composed of two monomers.
Also utilized for binder jetting, thermoplastic polyurethane (TPU) and the flame-retardant (FR) grade, TPU FR. The elastomer plastic materials are known for versatility.
According to Jabil, its TPU products are an easy to process, standard product for printing jobs that require elastomeric properties like compression set or soft touch to prevent scratching or marring, with high impact strength. Applications include jigs, fixtures, and tooling; touch pads; grips; feet; and other parts that require elastomeric properties.
For binder jetting, Tim Weber, global head of 3D materials, HP Inc., says the HP Metal Jet industrial solution uses a novel HP binder leveraged from HP’s two-dimensional (2D) latex business. This includes standard metal inject molding materials like 316L and 17-4 PH stainless steels.
DED
The DED processes takes metal materials, such as wire or powder, energizes them, and deposits directly onto a build tray or an existing part.
Similar to its solutions for binder jetting, Matt Torosian, director of product management, AM materials, Jabil, recommends its PA 12 copolymer, TPU, and TPU FR materials for DED.
Dr. Jacob Nuechterlein, president/founder, Elementum 3D, says currently the company only offers A6061-RAM2 for DED, but other material is being developed.
Touted as highly versatile and cost effective, Elementum 3D’s A6061-RAM2 is a general purpose AM aluminum alloy that features a good combination of ductility, strength, and thermal conductivity.
Material Extrusion
According to Siemens, material extrusion is an AM methodology where a spool of material, usually thermoplastic polymer, is pushed through a heated nozzle in a continuous stream and selectively deposited layer by layer to build a 3D object. Fused filament fabrication and fused deposition modeling are two examples of material extrusion technology.
“Material extrusion is typically not as fast or accurate compared to other types of AM. However, material extrusion technology and compatible raw materials, like nylon and acrylonitrile butadiene styrene (ABS) plastic, are both widespread and inexpensive, by so much in fact, that material extrusion is the most popular process for hobbyist-grade 3D printing at home. In manufacturing and industrial settings, material extrusion is commonly used for producing non-functional prototypes, or cost-effective rapid prototyping for multiple iterations of the same object,” states Siemens’ website.
Material extrusion is mostly used for plastics, but can also be used for metals and ceramics.
Torosian says polylactic acid, polyethylene terephthalate glycol, ABS, acrylonitrile styrene acrylate, polycarbonate, PA, and other long chain copolymers; TPU; and styrene ethylene butylene styrene, are suited for this technology.
Material Jetting
Material jetting, or poly jetting, is a 3D printing technology that produces smooth, accurate parts, prototypes, and tooling. According to Stratasys, with microscopic layer resolution and accuracy down to 0.014 millimeters, it can produce thin walls and complex geometries using the widest range of materials available with any technology.
For material jetting, HP uses PBF. The HP Multi Jet technology Fusion machine uses HP’s PageWide printing technology from the 2D business to bring functional plastic parts with high productivity. “The current material used for prototyping and production include PA 12, PA 11, and PA 12 with glass beads; and elastomers like TPA and TPUs, and a polypropylene,” says Weber.
also notes that several Elementum 3D materials used for material jetting include A6061-RAM2, A7050-RAM2, A2024-RAM2, A2024-RAM10, A1000-RAM10, A1000-AM, NI625-RAM2, NI718-RAM2, R80-RAM1, AMCopper-100, and Tantalum.
PBF
The PBF process includes a variety of popular 3D print methods, direct metal laser sintering, electron beam melting, selective heat sintering, selective laser melting, and selective laser sintering (SLS).
According to Loughborough University, PBF methods use either a laser or electron beam to melt and fuse material powder together. Electron beam melting, methods require a vacuum but can be used with metals and alloys in the creation of functional parts. All PBF processes involve the spreading of the powder material over previous layers.
The organization says there are different mechanisms to enable this, including a roller or a blade. A hopper or a reservoir below or aside the bed provides fresh material supply. Direct metal laser sintering is the same as SLS, but with the use of metals and not plastics. The process sinters the powder, layer by layer. Selective heat sintering differs from other processes by way of using a heated thermal print head to fuse powder material together. As before, layers are added with a roller in between fusion of layers. A platform lowers the model accordingly.
Torosian says Jabil PA 12 copolymer, TPU, and TPU FR are compatible with PBF.
Sheet Lamination
Sheet lamination processes include ultrasonic AM and laminated object manufacturing. According to Loughborough University, the ultrasonic AM process uses sheets or ribbons of metal, which are bound together using ultrasonic welding.
The process does require additional CNC machining and removal of the unbound metal, often during the welding process. Laminated object manufacturing (LOM) uses a similar layer by layer approach but uses paper as material and adhesive instead of welding. The LOM process uses a cross hatching method during printing to allow for easy removal post build. Laminated objects are often used for aesthetic and visual models and are not suitable for structural use.
Loughborough University says the process is low temperature and allows for internal geometries to be created. The process can bond different materials and requires relatively little energy, as the metal is not melted.
Vat Photopolymerization
Vat Photopolymerization includes several technologies like stereolithography, digital light processing (DLP), continuous liquid interface production, solid ground curing, and daylight polymer printing.
Toni Parker, marketing communications manager, Adaptive3D, says Adaptive3D prints with elastomers using DLP vat photopolymerization.
Cindy Deekitwong, global head of marketing for new business, Henkel, says LOCTITE 3D Printing supplies a variety of plastic photopolymer resins for vat polymerization 3D printing, including DLP and LCD processes. The company offers a diverse portfolio geared towards end-use industrial applications, including FST materials, superior strength materials, and high-energy return elastomers, she explains.
AM Materials
Within AM, several technologies are utilized including binder jetting, directed energy deposition (DED), material extrusion, material jetting, PBF, sheet lamination, and vat photopolymerization. Each process requires the right materials to perform properly.
Part two of this article series discusses use, pricing, and availability of popular AM materials.
Nov2021, Industrial Print Magazine