Phil Hutchinson, element14 Community Senior Specialist at Farnell, considers how to select the right 3D printer.

Phil Hutchinson, element14 Community Senior Specialist at Farnell, considers how to select the right 3D printer.

3D printing offers electronic engineers much greater flexibility to speed up innovation. Early adopters such as the aerospace and defense industries have long been using 3D printing for rapid concept modeling, component prototyping and the production of end products, without the constant retooling of manufacturing lines.

Although the technology has been around for nearly three decades, recent advances have made 3D printers a much more attractive investment for electronic engineers. 3D printers are now more affordable than ever, and some entry-level printers are below $200. There are also many more options available as the number of 3D printer manufacturers nearly tripled between 2014 to 2018 to about 120 today. In addition, quality and speed of print has improved and a wider variety of materials are available with which to print parts and models. As a result, and thanks to recent advancements such as the 3D printing of solid state metal, we’re beginning to see the emergence of 3D printed circuitry and according to an Ernst and Young study, printing electronics could lower prototyping time by 63 percent. 

Utilizing a 3D printing service, rather than purchasing a 3D printer outright, remains a viable option for many engineers, but when ready to make the leap engineers should carefully assess their 3D printing needs in terms of cost, quality, functionality and material requirements to ensure they get the right 3D printer for their needs. 

The Right Type

The first step to choosing the right 3D printer is understanding which kind of 3D printing technology to utilize. Two of the more prominent types are Fused Filament Fabrication (FFF) – also known as Filament Deposition Manufacturing (FDM) or Molten Polymer Deposition (MPD) – and Stereolithography (SLA), which uses laser or Digital Light Processing (DLP) resin printers. 

Fused Filament Fabrication (FFF) Printers

FFF printers use a filament of thermoplastic material fed through a heated moving head that extrudes layer after layer of plastic on a moving base that lowers with each layer deposited. It is the kind of technology most commonly used in desktop 3D printers and consequently, FFF tends to be more affordable, easier to use, and relative speedy in printing. 

On the downside, FFF printers can print less accurately than other types of 3D printers, which could be an issue for projects that demand very tight tolerances. FFF printers also tend to require more tuning and maintenance to keep them operating properly and the technology is sensitive to changes in temperature

Stereolithography (SLA) Printers

SLA printers (often referred to as resin printers) use a light-emitting device (laser or DLP) to fuse together the product from a tank of liquid photo-polymerizing resin or a bed of powder. A light beam laser sweeps the surface of the material based on the 3D design provided by the computer model, with the product progressively lifted up out of the material. 

Stereolithography’s big advantage is its greater precision and higher levels of detail making it a better choice for projects requiring more complex geometries and smoother, more realistic finishes. SLA printers are also well suited to smaller projects and very large projects that require high definition, and while FFF printers are generally fast, SLA printers are faster. 

But these advantages come at a price.  SLA printers cost significantly more (typically in the $1,000 – $10,000 range) and there are also fewer materials available, and they tend to be more expensive. Products produced with the thermoplastic resin or powder materials also tend to more fragile. 

The Right Materials

Materials are another important consideration when selecting a 3D printer. The variety of materials for 3D printing vary widely, even spanning into the edible (including chocolate, sugar and pancake batter) and construction-grade (as with 3D printed houses from extruded concrete). 

Electronic engineers will need to assess more conventional materials for their designs. 

Polylactic acid or polylactide (PLA) For FFF printers, polylactic acid or polylactide (PLA) is one of the most popular thermoplastic materials as its biodegradable and derived from natural resources such as corn and sugarcane. It is ideal for rapid prototyping ideas where form and aesthetics are the most important considerations. PLA also has greater tensile strength, so is less prone to warping. 

Acrylonitrile Butadiene Styrene (ABS) is another popular thermoplastic polymer for FFF printers. ABS printed products tend to have better flex strength and superior mechanical properties so is ideal if breakage is a concern. It’s also better suited for higher heat applications, as its structural integrity holds up better with rising temperatures.  

Polyethylene Terephthalate (PETG) is a polymer ideal for food-safe applications. It’s often used to make water bottles, food containers and similar plastic products as it doesn’t absorb water. It has strong mechanical properties, but can be challenging for beginners to use since it’s finicky when it comes to setting the right precise temperature, and often requires a lot of fine-tuning of the nozzle. 

Nylon: For applications that require even greater strength and durability than ABS, nylon is a popular choice. Nylon is very strong and quite flexible, making it well suited for moving, high impact, or abrasive part applications. Its strength stems in part from its high melting temperature, but nylon can be toxic in its melted state. Nylon is also not well suited for applications where moisture or humidity are involved. 

Thermoplastic Elastomer (TPE) is a favorite material when flexibility matters. Similar to rubber, TPE results in more elastic and stretchable products, but, it softness and elasticity significant limits the breath of applications it’s suitable for. 

Materials for Resin- or powder-fusing SLA printers are usually bought with a more focused application in mind, which impact what resins and powders should be used. These materials and printers tend to be higher-end than consumer-level 3D technologies. There are five basic types of resin – standard (for lower-budget projects), grey (for smoother finishes), mammoth (for large-sized prints), transparent (for transparent surfaces), and high-detail resin (for more complicated geometries). 

Polymer Powders are used is laser sintering, where tiny particles of the polymer are fused together by a high-power laser to form the 3D object. Powers are ideal for projects that require a higher-performing plastic, are metal impregnated, or require the flexibility of rubber with the strength of plastic. 

Additional considerations

Infill is important material consideration, and services as the “filler” of the empty spaces within a 3D printed model. Infill produces a repetitive structure (like a honeycomb) which pattern and density impacts the model’s strength and weight – without it, many models would be too fragile. Since infill comes in many sizes and patterns, engineers need to determine the right combination for their model’s purpose – the higher the density, the heavier and stronger the print. 

The Right Support for your 3D Model

Similarly, some 3D models need support within empty spaces that needs to be removed after printing is completed. Two types of plastics are commonly used as Support Material:  Polyvinyl Alcohol (PVA) and High Impact Polystyrene (HIPS).  PVA is water soluble and relatively easy to remove, though it’s sensitivity to temperature and humidity can make it chemically unstable if not stored and handled correctly, causing the extruder to jam. HIPS don’t suffer from this problem, but it is not as easy to remove and requires the use of Limonene, which is found in household cleaners and food flavoring products. 

Engineers also need to consider the model’s support structure and overhangs. Many models need a support structure on which to extrude the model layer by layer. These support structures can affect the look and surface of the finished model, often requiring surface finishing to remove roughness and blemishes. Determining whether a model requires support is important because it impacts the model’s stability and material costs. If the model has an overhang (or bridge) with nothing below it for support, a support structure may be necessary although if the overhang tilts at a 45-degree angle or less, a support structure may not be needed. For a bridge, the rule of thumb is anything less than 5mm in length probably won’t require a support structure. 

The Right Slicer

Preparing the model for printing requires choosing the right slicer:  the software which generates the instructions for the printer to follow. The slicer translates the CAD drawing into geometric printable code, essentially slicing the 3D model into the individual thin layers that the printer extrudes as the model takes shape. Hundreds of slicing software programs are available, many of them for free and engineers should  consider  which Operating System it supports, which file formats it supports (e.g. STL, OBJ, X3D or 3MF), integration with CAD software, cloud- or desktop-based, 3D printer compatibility, open source vs. proprietary, infill options and support control when choosing which one to use. 

So which 3D printer is right for you? Document the factors of cost, quality, functionality and material requirements to narrow down the field and ensure the right selection.