I often find that when I start talking to people who know a lot about 3D printing they use a flurry of acronyms, such as SLA, FDM or SLS. Unless you have some prior knowledge of 3D printing, it can sound daunting and complex and they may as well be speaking another language.

To clarify things, this article will summarise the different types of 3D printing and explore the pros and cons of these methods relating specifically to the architecture industry. After a quick introduction to the basics, I will cover the three types of 3D printing that are the most applicable to the architecture industry. These include:

1. Fused Deposition Modeling (FDM)

2. Selective Laser Sintering (SLS)

3. Stereolithography (SLA) and Digital Light Processing (DLP)

What is 3D Printing?

Before I describe the pros and cons of each method it is useful to give a quick overview of what 3D printing is, and how it works. Traditional manufacturing techniques such as machining and carving are called subtractive manufacturing. This is done by cutting material from a block until you have created the form you desire. 3D printing is different, as it is an additive manufacturing technique. This process builds objects by adding material layer by layer to create the desired form. All types of 3D printing essentially work like this, however, each method can differ in the way in which they apply each layer. There are many programs that take your 3D CAD model and slice it into layers to give the 3D printer the information it needs to create your print.

Support structure is another important aspect of 3D printing. Many 3D printing techniques use various types of support to help them build complex geometries. During the print process, the printed form can be unstable before it is completed, the support structure helps keep the print structurally sound until the print is completed. Once the printing process is complete the support structure can be removed, this is easy in some cases but not in others. A good way to imagine the support structure is by picturing scaffolding around a building. The scaffold helps keep the building safe and secure until the building is complete, just like the support structure around your 3D printed part.

Fused Deposition Modeling (FDM)

FDM is essentially a computer-controlled hot glue gun, it does this by heating and then extruding thermoplastics through a fine tip nozzle. It will also print the support structure, as described above, that can be dissolved once the print is completed leaving you with the desired print. FDM is a widespread and commonly used 3D printing technique, especially amongst hobbyist makers. There are currently many cheap desktop FDM printers on the market.

Pros

• Cheap and easy - you can pick up a desktop FDM printer for as low as $300NZD. The maintenance is simple and there are no toxic chemicals or fine particulates, meaning they are a great way to get started in the 3D printing world.

• Quick - a lot of printers have adjustable speed and quality settings so if you want to bang out a prototype in a few hours this can be a great option if the quality of the print is not as important.

• Durable - the print material is strong. For example, if you want to mock up functional prototypes of a door handle, FDM is a great option.

• Material options - there is a wide range of material options including a range of plastics, clay, glass, concrete and many more.

Cons

• Low fidelity - the print quality of FDM is lower, especially on cheap machines. This means a longer clean-up time because the layers left by the manufacturing process will need to be removed.

Selective Laser Sintering (SLS)

SLS uses a laser to melt layers of powdered material into the desired form. The bed of the printer lowers and then a new layer of powder is applied. Then a laser fires into the powder which selectively melts or sinters an area of the powder which fuses it with the layer below. This process is repeated to build up the object layer by layer. SLS is a great technique for 3D printing, however it is expensive for use in-house.

Pros

• No support structure - because of the build technique the print is supported by the surrounding powder which is easy to remove on completion.

• High fidelity - you can print very high-resolution prints with fine details. The surface is a consistently chalky texture.

• Strong - the parts are very strong so it is great for creating functional prototypes or final product prints.

Cons

• Expensive - SLS machines are expensive, with some desktop options starting at around $8,500NZD. Industrial SLS machines cost hundreds of thousands of dollars.

• Fine particulates - the cleanup process for an SLS machine involves removing the excess powder from the print. To do this you need a dedicated space with good extraction and access to other health and safety equipment.

Stereolithography (SLA) and Digital Light Processing (DLP)

SLA and DLP are similar technologies. They both use a photopolymer resin that is solidified by a certain wavelength of UV light. SLA uses a small laser to trace out the shape of the cross-section of the object that is being printed, which solidifies and bonds the resin to the previous layer. DLP is similar, however it exposes UV light to the entire layer at once. Because both these techniques use light to construct the print, a much higher resolution can be achieved. SLA and DLP are more expensive than FDM but the resolution means you can get an almost completely smooth surface without any clean up involved.

Pros

• Very high fidelity - the print quality and detail achievable using SLA and DLP printing are the best available.

• Cost-effective - although they are more expensive than FDM, there are some really well-priced desktop SLA and DLP printers on the market starting at around $450NZD.

• Speed - DLP, in particular, can print quickly because it cures an entire layer at once as opposed to SLA which draws out each layer with a laser.

Cons

• Harmful chemicals - the resin that is cured emits toxic fumes and can irritate the skin. The uncured resin should be treated with care and it is a good idea to wear a chemical mask and gloves and also be in a well-ventilated area.

• Support structure - this can sometimes foul the surfaces of your print depending on the orientation of your prints.

Conclusion

3D printing is a powerful tool that is great for design development and communication. People are usually more receptive to a physical model than trying to understand a stack of technical drawings. In the field of architecture, 3D printing is lowering the barrier to entry for architects to use physical models. As this article has shown, each technique of 3D printing has its pros and cons. While FDM is a great method for in-house prototyping, SLA and SLS are great for high-quality presentation models and can blow your clients away. Further, there are a lot of online 3D printing services which are a great way to access the benefits of 3D printing without bringing the complexities and health and safety issues into your practice. Shapeways is a great example of this type of service.