Introduction

3D printing materials and manufacturing processes go together hand-with-hand: often choosing a material, also dictates what 3D printing processes are available to use. 

But with such a vast selection of 3D printing material options, how can a designer make an informed decision?

In this article we present a comprehensive overview of the 3D printing materials currently available in the market. We grouped them together into categories to simplify the selection process and make decision-making more actionable. 

3D Printing Materials

Let's start with a quick refreshment on Material Science...

3D printing materials usually come in filament, powder or resin form (depending on the 3D printing processes used). Polymers (plastics) and metals are the two main 3D printing material groups, while other materials (such as ceramics or composites) are also available. Polymers can be broken down further into thermoplastics and thermosets.

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Thermoplastics:

Thermoplastics can be melted and solidified over and over again, while generally retaining their properties. Both traditional injection molding, as well as the FDM and SLS printing processes, make use of thermoplastics by heating up solid thermoplastic to a malleable state and injecting or extruding it into a die or onto a build platform where it then solidifies.

Thermoplastics are best suited for functional applications.

These materials generally have good mechanical properties and high impact, abrasion and chemical resistance. 3D printed engineering thermoplastics (such as Nylon, PEI and ASA) are widely used to produce end-use parts for industrial applications.

SLS parts have better mechanical properties and higher dimensional accuracy than FDM, but the latter is more economical and has shorter lead times.

Typical 3D printing thermoplastics:

SLS: Nylon (PA), TPU

FDM: PLA, ABS, PETG, Nylon, PEI (ULTEM), ASA, TPU

A functional bracket with hollow sections printed using SLS in Nylon

The pyramid below shows the most common thermoplastic materials for 3D printing. As a rule of thumb, the higher up a material is in the pyramid, the better its mechanical properties and the harder it generally is to print with (higher cost):

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Thermosets:

Unlike thermoplastics, thermosets do not melt. Thermosets in 3D printing typically start as a viscous fluid (resin) and are cured to become solid, via exposure to UV light. Once solid, thermosets cannot be melted and instead will lose structural integrity when subjected to high temperatures.

Thermosets (resins) are best suited for applications where aesthetics are key.

These material options produce parts with smooth injection-like surfaces and fine details. Generally, they have high stiffness, but are more brittle than thermoplastics, making them less suitable for functional applications. Speciality resins are available though, that are designed for engineering applications (mimicking the properties of ABS and PP) or dental inserts and implants.

Material Jetting produces parts with superior dimensional accuracy and generally smoother surfaces than SLA, but at a higher cost. Both processes use similar photocurable acrylic-based resins.

Typical 3D printing thermosets:

Material Jetting: Standard resin, Digital ABS, Durable resin (PP-like), Transparent resin, Dental resin

SLA/DLP: Standard resin, Tough resin (ABS-like), Durable resin (PP-like), Clear resin, Dental resin

Small bracket 3D printed with Material Jetting

Ring with intricate details 3D printed in Castable Resin with SLA/DLP

Polymer Composites

Both thermoplastic and thermoset polymers can be reinforced with other high strength materials improving their mechanical properties or giving them other unique characteristics.

For example, SLS powder can be filled with carbon, aluminum, graphite and glass particles increasing their mechanical performance, wear and thermal resistance and stiffness.

Furthermore, composite parts reinforced with continuous carbon fibers, kevlar fibers or glass fiber can be manufactured through the FDM process, creating plastic components with strength-to-weight ratio comparable to metals.

Functional joint, 3D printed with FDM in nylon and reinforced with continuous carbon fibers. Courtesy of Markforged

Many "exotic" filaments, such as woodfill or metalfill PLA, are also available for FDM, resulting in parts with a unique appearance.

Phone speaker for the Fairphone 2, 3D printed with FDM in woodfill PLA

SLA resins filled with ceramic powder have improved wear resistance, making them ideal materials for tooling applications (such as 3D printed injection molds).

Typical composite 3D printing materials:

SLS: Carbon filled, Glass filled, Mineral filled

FDM: Carbon filled, Woodfill, Metalfill, Carbon-fiber reinforced, Kevlar-fiber reinforced, Fiberglass reinforced

SLA/DLP: Ceramic filled

Metals

Metal printing allows for high-quality, functional and load bearing parts produced from a variety of metallic powders.

Metal 3D printed parts have excellent mechanical properties and can operate at wide range of environmental conditions. The freeform capabilities of 3D printing make them ideal for lightweight applications for the aerospace and medical industries.

DMLS/SLM parts have superior mechanical properties and tolerances over Binder Jetting, but Binder Jetting can be up to 10x cheaper and can produce much larger parts. Low-cost extrusion-based (FDM) metal 3D printing systems are expected for release in 2018.

Typical 3D printing metals:

DMLS/SLM: Stainless Steel, Titanium, Aluminum

Binder Jetting: Stainless Steel (bronze-filled or sintered)

Metal part 3D printed in aluminium with SLM

An oil and gas strator printed in stainless steel (bronze-filled) with Binder Jetting. Courtesy of ExOne

Other materials

Other materials can also be 3D printed, but have limited applications. These materials include ceramics and sandstone in full-color with Binder Jetting. They generally have poor mechanical properties and are optimized for a single application, such as full-color figurine printing or sand cast manufacturing.

Other 3D printing materials:

Binder Jetting: Full-color sandstone, Ceramics

Large multi-part sand casting assembly 3D printed with Binder Jetting. Courtesy of ExOne

Compare 3D printing Materials

The guidelines and tables of this article should already give the reader a basic understanding and reference for choosing the right 3D printing material.

If you want to view, compare and search for 3D printing materials with specific mechanical or physical properties, the Material Index is the most comprehensive online library of 3D printing materials.

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