08 Aug 3D Printing Materials: What, How and Why?
3D printing technology has advanced dramatically over recent years. Reliable and cost-effective for both large and small product runs, the process can be used with a variety of materials.
The most commonly used commercial processes work with resin, nylon and various metals to create the desired parts. There are also some very specialised printers that can process other materials, such as biological matter and concrete, which is a whole subject in its own right.
No matter what material is used, the basics of 3D printing is that layer upon layer of matter is piled upwards, with each curing (hardening) and melding to the one above and below it.
Using resin to build 3D printed parts
Resin is one of the most commonly used materials for 3D printed parts. There are a variety of 3D printing processes used, but the basic premise of them all is that they direct light onto the resin, causing it to solidify.
There are three commonly used processes used to do this:
- Stereolithography (SLA): The process uses mirrors to aim a laser (or two) over a vat of liquid resin. This builds up thin layers of resin that gradually form the desired shape.
- Masked stereolithography (MSLA): This is an advanced form of SLA that uses an LED array to direct UV light through an LCD screen. This screen masks the light source so it doesn’t directly come into contact with the thermoplastic resin.
- Digital light processing (DLP): Uses a flash of light to cure an entire layer of material at a time and is directed at the resin by an array of tiny mirrors.
Each process has its pros and cons. SLA is accurate, cost-effective and one of the most commonly used forms of commercial 3D printing. MSLA is less common – mainly because the equipment is highly specialised (with associated high purchasing costs). It also requires complete darkness to operate and it is somewhat more messy than other processes. However, MSLA is faster because it can cure an entire layer in a single pass, no matter how thick it might be.
DLP is the fastest type of resin 3D printing. This is because it can cure a whole layer at a time, rather than waiting for each one to be individually printed. It’s a good option for producing large runs of high-quality parts cost-effectively. However, these attributes also mean that it might not be the right process for printing highly intricate resin parts.
Resin is a versatile material that’s ideal for detailed, complex geometries. It’s the perfect choice for a non-functional prototype, thanks to the relatively low cost and speed. The material is highly durable and is ideal for the creation of small, highly detailed parts that require a top-quality surface finish.
The case for nylon
Nylon is another commonly used material for. It’s a plastic polyamide that softens when subjected to heat and hardens as it cures. One of the biggest advantages is that the heating and cooling process can be carried out multiple times without causing damage to its mechanical properties.
Because of this, it’s often combined with other plastics to enhance their performance.
Two commonly used processes used for nylon 3D printing are:
- Multi Jet Fusion (MJF): Fuses and heats agents together over a bed of nylon powder. Each layer is covered by the powder – the process is then repeated to build the shape.
- Selective laser sintering (SLS): A very high-powered laser is used to layer and fuse polymer powder particles together.
Nylon is commonly used for parts used within many industries, such as fashion, electronics, automotive, manufacturing and textiles. Some of the most popular applications where 3D printing is used include cable ties, fasteners and gears. This is because of the material’s excellent hard-wearing properties.
Metals: including stainless steel and titanium
The durability, affordability and resistance to heat and corrosion make stainless steel (including 316L stainless) ideally suited to the 3D printing process. Stainless steel is commonly used to print complex, fully functioning industrial prototypes, obsolete components, automotive parts and more.
Some of the properties of 3D printed stainless steel 316L include:
- Non-magnetic
- Fast build time
- High ductility
- High resistance to corrosion
One of the best 3D printing technology for stainless steel is that offered by specialist provider, Markforged. The company’s tech has exploded onto the market, providing exceptionally high repeatability in short timescales and, very importantly, at a fraction of the historical cost.
Titanium also lends itself extremely well to the 3D printing process. The world of medicine has, quite literally, been revolutionised by the process. The metal is as strong as steel but only half the weight, meaning that it can be implanted into the human body and, in many cases, has proven lifesaving or life changing.