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Selecting the right 3D printing process

Written by Alkaios Bournias Varotsis

Selecting the right 3D printing process

Introduction

3D printing or Additive Manufacturing is an umbrella term that encompasses multiple processes. Every 3D printing process has its benefits and limitations and each is more suitable for certain applications than others.

In this article, we give several easy-to-use tools to aid you to select the right 3D Printing process for your needs. Use the following graphs and tables as a quick reference to identify the process that fulfills best your design requirements.

We approached the process selection from three different angles:

To make the information in this article actionable for the reader and always relevant in the ever-evolving 3D printing landscape, some high-level generalizations were introduced that will be discussed in each section when necessary.

Selecting a process by material

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.

If the required material is already known, selecting a 3D printing process is relatively easy, as only a few technologies produce parts from the same materials. In those cases, the selection process usually becomes a cost versus properties comparison.

Thermoplastics:

Thermoplastics are best suited for functional applications, including manufacturing of end-use parts and functional prototypes.

They have good mechanical properties and high impact, abrasion and chemical resistance. They can also be filled with carbon, glass or other additives to enhance their physical properties. 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 and physical properties and higher dimensional accuracy, but FDM 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

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):

Thermosets (resins):

Thermosets (resins) are better suited for applications where aesthetics are important, as they can produce parts with smooth injection-like surfaces and fine details.

Generally, they have high stiffness but are more brittle than thermoplastics, so they are not suitable for functional applications. Specialty resins are available, 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, but at a higher cost than SLA/DLP. Both processes use similar photocurable acrylic-based resins.

Typical 3D printing thermosets (resins)
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
Metals:

Metal 3D printed parts have excellent mechanical properties and can operate at high temperatures. 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, but Binder Jetting can be up to 10x cheaper and can produce much larger parts.

Typical 3D printing metals
DMLS/SLM Stainless Steel, Titanium, Aluminum
Binder Jetting Stainless Steel (bronze-filled or sintered)
Other materials:

Other materials can also be 3D printed, but they are not as widely used, since their applications are limited. These materials include ceramics and sandstone in full-color with Binder Jetting.

Other 3D printing materials
Binder Jetting Sand, Ceramics
Pro Tip:

Due to the additive nature of the technology, 3D printed parts will often have anisotropic mechanical properties, meaning that they will be weaker in the z-direction. For functional parts, this characteristic should be taken into account during design.

For example, see how the properties of SLS nylon compare to bulk nylon in this article.

A test bracket printed in range of different 3D printed materials

Selecting a process by use-case

It is important to determine early in the selection process whether the main design consideration is function or visual appearance. This will help greatly in choosing the most suitable process.

As a rule of thumb, thermoplastic polymer parts are better suited for functional applications while thermosets are best suited for visual appearance.

Functionality:

The flowchart below can help you identify the most suitable 3D printing process based on common design requirement for functional parts and prototypes.

Here are some more details:

A functional bike tool 3D printed in carbon-filled nylon with SLS.

Courtesy Rehook

Visual Appearance:

When visual appearance is the main concern, then the 3D printing process selection can be simplified using the flowchart below.

Here is some more information:

Model of a Cyborg 3D printed with Material Jetting after painting.

Courtesy Factor 31

Selecting a process by manufacturing capabilities

When the model design is already finalized, the capabilities of each 3D printing technology will often play the main role in the process selection.

It is important to have an overview of the fundamental mechanics of each process to fully understand their key benefits and limitations. For this, see the dedicated introductory articles to each technology in the following chapter of the Knowledge Base.

Here are some handy rules to help you interpret the data:

Dimensional accuracy Typical build size Support
FDM ± 0.5% (lower limit ± 0.5 mm) - desktop ± 0.15% (lower limit ± 0.2 mm) - industrial 200 x 200 x 200 mm for desktop printers Up to 900 x 600 x 900 mm for industrial printers Not always required (dissolvable available)
SLA/DLP ± 0.5% (lower limit: ± 0.10 mm) - desktop ± 0.15% (lower limit ± 0.05 mm) - industrial 145 x 145 x 175 mm for desktop Up to 1500 x 750 x 500 mm for industrial printers Always required
SLS ± 0.3% (lower limit: ± 0.3 mm) 300 x 300 x 300 mm (up to 750 x 550 x 550 mm) Not required
Material Jetting ± 0.1% (lower limit of ± 0.05 mm) 380 x 250 x 200 mm (up to 1000 x 800 x 500 mm) Always required (always dissolvable)
Binder Jetting ± 0.2 mm (± 0.3 mm for sand printing) 400 x 250 x 250 mm (up to 1800 x 1000 x 700 mm) Not required
DMLS/SLM ± 0.1 mm 250 x 150 x 150 mm (up to up to 500 x 280 x 360 mm) Always required

Layer height

Another important aspect to consider when choosing a technology is the impact of layer height.

Due to the additive nature of 3D printing, layer height determines the smoothness of the as printed surface and the minimum feature size a printer can produce (in the z-direction). Using a smaller layer height also makes the stair stepping effect less prominent and helps produce more accurate curved surfaces.

Typical layer thickness
FDM 50 - 400 μm (most common: 200 μm)
SLA/DLP 25 - 100 μm (most common: 50 μm)
SLS 80 - 120 μm (most common: 100 μm)
Material Jetting 16 - 30 μm (most common: 16 μm)
Binder Jetting 100 μm
DMLS/SLM 30 - 50 μm

Rules of Thumb

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