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3D Printing Materials Evolve

10 August 2015

What you need to know about 3D printer materials: three trends, one revolution

Personal 3D printing is finally coming of age as a new generation of materials opens up new applications and makes it easier than ever for users of all skill levels to enjoy pro-grade results. The printers themselves have evolved quickly since the first RepRap machines shuddered to life in late 2007, but their seemingly-limitless potential has been limited by the properties of the materials they print. Nevertheless, this gap has begun to close rapidly, thanks to three recent trends in 3D printing materials.

Fig.1: New 3D printing materials, such as the carbon-impregnated filament shown here, are enabling both hobbyists and entrepreneurs to apply Maker technology to an ever-growing range of applications. (Image Credit: Proto-Pasta)  Fig.1: New 3D printing materials, such as the carbon-impregnated filament shown here, are enabling both hobbyists and entrepreneurs to apply Maker technology to an ever-growing range of applications. (Image Credit: Proto-Pasta)

Encouraged by the industry's 36% annual growth rate, filament manufacturers are investing heavily in improving existing materials and introducing new ones. They are also addressing a growing market for materials with specialized properties such as extreme flexibility, wear resistance, and even the ability to conduct electricity. How are these three trends helping put the industry on track for the $35.8 billion in total sales predicted for 2020 by a recent market 3D Printing study, published by IHS Global Insights.

New tricks for old materials

The Acrylonitrile Butadiene Styrene (ABS) and polylactic acid (PLA) filaments commonly used in most non-professional machines are great for making desk ornaments, simple toys and other parts but did not always offer the strength or flexibility needed for many applications. Meanwhile, lot-to-lot variations in the melting point, adhesion and other properties of most materials made it difficult to produce consistent results, even for 3D pros.

Recently however, filament manufacturers have begun to tame the unruly chemistry behind their existing PLA, ABS and nylon products to produce filaments with more consistent melting temperatures, viscosities, and other critical characteristics. These third-generation filaments print smoother, more tightly-bonded layers that produce stronger, more attractive projects and are generally easier to use.

Manufacturers are also creating new versions of familiar materials that closely match the requirements of a particular set of applications. For example, Nylon has also benefitted greatly from application-specific formulation. It has always been the material of choice for gears, propellers, tools and other applications where strength, wear-resistance and resilience were critical but its "slippery" properties made it challenging to print. Problems such as poor adhesion to printer beds, and even to previous nylon layers, made printing high-quality parts a challenge not for all but for the serious 3D-ers.

Taulman3D has also been very active in this area and now offers four different nylon formulations which offer improved print-ability. Each of the formulations has a unique combination of mechanical properties which allow designers to choose a mix of strength, hardness, pliability, and temperature characteristics that closely match their application requirements. Taulman has also introduced a new industrial-grade PLA which is stronger, less brittle, and exhibits even better transparency than its 1st-generation of PLA materials.

Another sign of the industry's maturation is the growing availability of filament made from recycled materials. Dimension Polymers' has recently introduced the first professionally engineered ABS filament made from 100% recycled plastic. Their high-quality product is produced using a proprietary set of blending, processing, and quality control testing steps which insure they meet the strict material property and consistency standards that are essential for high quality 3D printing. Dimension Polymers, and its inevitable competitors, will play a key role in making 3D printing a truly sustainable manufacturing technology.

Alloys

There is also a growing interest in so-called alloys, compounds of multiple materials which yield unique properties. For example, Proto-Pasta has formulated a material called PC-ABS Alloy that provides significant improvements (over standard ABS) in heat deflection, impact resistance, rigidity, and flexibility.

Taulman3D has also introduced its Alloy 910, a highly-durable material which combines high tensile strength and good elongation characteristics. Parts printed using Alloy 910 exhibit a tensile strength of 8,100 PSI and close to 12,000 PSI when injection molded. This makes it suitable for true industrial applications including large motor mounts and vibration isolators, high end gears and cams and chemical-resistant mechanical components.

New filaments on the block

There are also a growing number of new materials hitting the market which offer users new choices in mechanical properties, appearance, and even texture. Consider for example, Thermoplastic Urethane (TPU), a tough, flexible material suitable for applications like cable sheathing, handles or seals. It’s soft, UV and ozone resistant, offers excellent weather-proofing and abrasion resistance, making it very suitable as a coating for “soft-touch” surfaces on vehicle interiors. TPU is available today at Airwolf, German Rep Rap and others.

3D printing enthusiasts and Maker-entrepreneurs will both find a lot to like about Polyethylene terephthalate (PETT). This variant of the more-common PET material offers high strength, excellent inter-layer bonding, and great optical properties. Some PETT materials, such as Taulman's t-glase, offer high clarity and exceptional optical properties which make them a good choice for printed jewelry and light guides.

Fig.2: Taulman3D's t-glase offers excellent mechanical and optical properties. (Image Credit: Taulman3D)Fig.2: Taulman3D's t-glase offers excellent mechanical and optical properties. (Image Credit: Taulman3D)

There have also been some important developments in support materials, filaments designed specifically to anchor or buttress especially delicate areas of a part during printing which can be easily removed when completed. Makers printing with ABS, PLA and PLA alloys are rapidly discovering that Polyvinyl alcohol (PVA) is especially well-suited as a support material for their applications. This is a water soluble material and can be used to support objects with large overhangs as well as cut-outs and then be removed using ordinary tap water. The resulting solution's non-toxic properties allow it to be disposed of by pouring it down the drain.

Specialty materials for special effects

The 3D materials revolution has also unleashed a steady stream of more specialized filaments which gaps in form or function left by conventional printing materials. One of the most popular categories is flexible materials such as NinjaFlex, Orbitech's BendLay, and Taulman's PCTPE (Plasticized Copolyamide TPE). They can be used to make hinges and other highly flexible utility/industrial parts including cell phone cases, durable prosthetics and elements of wearables such as elbow/knee guards and embellishments for cosplay outfits or high-fashion wearables.

Fig.3 NinjaFlex can applied to function or fashion with equal success. (Image Credit:NinjaFlex)Fig.3 NinjaFlex can applied to function or fashion with equal success. (Image Credit:NinjaFlex)

Many manufacturers are also offering composite filaments, made by blending polymers with non-polymer materials, such as wood or glass fibers, or even metal particles. Among the first pioneering composites was Laywoo-D3, a filament composed of ABS and recycled wood fibers. It prints like ordinary filament but creates objects that look, feel and work like natural wood. It is now being produced by several manufacturers, along with a variant, called Laybrick, which blends the same polymers with super-fine milled chalk to produce printable brick or natural sandstone.

Fig.4: LayBrick and LayWoo-D filaments allow makers to print simulated stone, brick, and wood that can be worked with ordinary hand tools. (Image Credit: 3D-ers.org) Fig.4: LayBrick and LayWoo-D filaments allow makers to print simulated stone, brick, and wood that can be worked with ordinary hand tools. (Image Credit: 3D-ers.org)

Composites containing metallic powders such as iron, brass, or even magnetized ferrite are gaining popularity among artistically-inclined makers. The look and the heft of metallic composites make them perfect for jewelry, costumes, props, figurines, crafting, robots, and more. Proto-Pasta, a leading specialty filament maker even offers a PLA/Stainless Steel composite with printing properties that are comparable to standard PLA but results in heavy prints that can be finished post-print to closely resemble solid metal.

Fig.5: A printed stainless steel figurine, before and after polishing. Magnetic Iron PLA filament responds to magnets and behaves similarly to pure iron, even to the point of rusting. (Image Credit: Proto-Pasta)Fig.5: A printed stainless steel figurine, before and after polishing. Magnetic Iron PLA filament responds to magnets and behaves similarly to pure iron, even to the point of rusting. (Image Credit: Proto-Pasta)

Filaments compounded with carbon fiber are becoming increasingly popular because of the slick, high-tech look they add to a project. Filaments containing 10%-30% fiber are available from several vendors, including German RepRap and Proto-Pasta. They deliver increased rigidity which may make them suitable for mold construction but are not as strong as unadulterated material.

Fig.6 A stringed instrument printed in carbon Fiber PLA. (Image Credit: Proto-Pasta)Fig.6 A stringed instrument printed in carbon Fiber PLA. (Image Credit: Proto-Pasta)

One of the most unique specialty composites is conductive filament. Compounded with various metallic compounds, materials like Proto-Pasta's conductive PLA are opening up entirely new possibilities for both amateur and commercial designers.

Due to their high resistance, these materials are not intended for high-powered connections but they are a great choice for low-voltage circuitry applications. This includes touch sensor projects, lighting low-current LEDs and using printed objects to interact with touch screens.

To contact the author of this article, email engineering360editors@ihs.com

Related Links:

3-D Printing as a Technology Driver of Environmental Sustainability



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