3D printing is an amazing technology that has massive significance in many industries, mainly due to its ability to print strong materials, in unorthodox shapes. Some technologies still can’t even produce some shapes that 3D printing can with no issues.
So it begs the question, what materials cannot be 3D printed?
Materials such as wood, cloth, paper and rocks cannot be 3D printed because they would burn before they can be melted and extruded through a nozzle.
This article will go through to answer some common questions about the capabilities and limitations of 3D printing, in terms of materials that you can and can’t print, as well as shapes.
What Materials Cannot Be 3D Printed?
The main answer here is that you cannot print with materials that can’t be melted, into a semi-liquid state which can be extruded. If you look at how FDM 3D printers work, they melt thermoplastic materials from a spool, with tight tolerances of ±0.05 and lower.
Materials that burn rather than melt at high temperatures are going to have a hard time being extruded through a nozzle.
As long as you can satisfy the semi-liquid state and tolerances, you should be able to 3D print that material. Many materials do not satisfy these properties.
On the other hand, we can also use powders for metals in a process called Selective Laser Sintering (SLS), which uses a laser to sinter powdered material and bind together to create a solid model.
Materials that cannot be 3D printed are:
- Real wood, although we can create a hybrid of PLA and wood grains
- Rock – although you could melt volcanic material like absalt or rhyolite
I actually couldn’t come up with many materials that can’t be 3D printed, you really can make most materials work in some way or another!
It might be a little easier to look towards the other side of this question to get more knowledge about materials within the 3D printing space.
What Materials Can Be 3D Printed?
Okay, so you know which materials can’t be 3D printed, but what about materials that can be 3D printed?
- Metals (titanium, stainless steel, cobalt chrome, nickel alloy etc.)
- Polycarbonate (very strong filament)
- Concrete (3D printed houses)
- TPU (flexible material)
- Bio-Materials (living cells)
- Electronics (circuit boards)
- Gold (possible, but this method would be quite inefficient)
- Carbon Fiber
- Wood-fill PLA (can have around 30% wood particles, 70% PLA)
- Copper-fill PLA (‘80% copper content’)
- HIPS and many more
You’d be surprised how far 3D printing has developed in recent years, with all kinds of universities and engineers creating new methods to 3D print different types of objects.
Even electronics can be 3D printed, which is something most people would never have thought would be possible.
Yes, there are also actual bio-3D printers available that people use to print living cells. They can be priced anywhere from $10,000-$200,000 and basically use additive manufacturing of cells and biocompatible material to layer a living structure which can mimic natural living systems.
Things like gold and silver can be made into 3D objects with the help of 3D printing, but not actually 3D printed. It’s made through a process of printing wax models, casting, melting the gold or silver, then pouring that molten gold or silver into the cast.
Below is a cool video that shows how a silver tiger ring can be created, going from design to the final ring.
The process is really specialized and requires proper tools and equipment to make it work, but the best thing about it is how detailed the model turns out, and how it is created with the significant help of 3D printing.
The customization with 3D printing is the best part about the technology, being able to personalize your own objects with ease.
What Shapes Cannot Be 3D Printed?
Practically speaking, you’re going to have a hard time finding what shapes cannot be 3D printed because there are many 3D printing techniques which can overcome limitations.
I think you’ll find several amazingly complex shapes and models by looking at the Mathematical Tag on Thingiverse.
Or the Trefoil Knot, created by shockwave3d on Thingiverse.
Shapes that FDM have trouble printing, can usually be done with SLA printing (curing resin with laser beams) and vice versa.
Normal 3D printers can have trouble printing:
- Shapes that have little contact with the bed, like spheres
- Models that have very fine, feather-like edges
- 3D prints with large overhangs or printing in mid-air
- Very large objects
- Shapes with thin walls
A lot of these troubles can be overcome using various assisted printing methods such as using support structures for overhangs, changing the orientation so that thin parts aren’t the foundation of the print, using rafts and brims as a solid foundation, and even dividing models in pieces.
Shapes with Little Contact to the Bed
Those shapes which will have a small base and little contact with the bed cannot be 3D printed directly like other shapes are 3D printed. The reason is simply that the object will pop off the bed even before the print is completed.
This is why you cannot create a sphere object easily as the contact with the surface is too little, and the body is too big that it will remove itself during the process.
However, you can do such printing by using a raft. The raft is a mesh of filaments which are placed on the build platform, on which the first layer of the model is printed
Fine, Feather Like Edges
3D printing very thin features like a feather, or knife edge is almost impossible with 3D printing because of the orientation, XYZ accuracy and general method of extrusion.
This could only be done on extremely precise machines of a few microns, and even then it won’t be able to really get edges as thin as you might want. The technology first has to increase its resolution passed the desired thinness you want to print.
Prints with Large Overhangs or Printing in Mid-Air
Objects which have large overhanging parts are challenging to print, and sometimes it is impossible to.
This problem is simple: if the shapes that are being printed are hanging too far from the previous layer, and their size is large, they will break off before the layer can properly form in place.
Most people would think you can’t print on top of nothing, because there needs to be some kind of foundation, but when you really dial in your 3D printer along with the settings, a phenomenon called bridging can really come in handy here.
Cura has some assistance to improve our overhangs with the ‘Enable Bridge Settings’ option.
Bridging can significantly be improved with the right settings, along with a Petsfang Duct, as you can see in the video below.
He managed to relatively successfully 3D print an overhang that was 300mm long. which is very impressive! He changed the print speed to 100mm/s and 70mm/s for infill, but only because the print would take a long time, so even better results are very possible.
Luckily, we can also produce support towers beneath these big overhangs, to hold them up and allow them to keep shape.
Very Large 3D Prints
Most FDM 3D printers range from around 100 x 100 x 100mm to 400 x 400 x 400mm, so finding a 3D printer that can print large objects in one go is going to be difficult.
The biggest FDM 3D printer I could find is the Modix Big-180X which has a massive build volume of 1800 x 600 x 600mm, weighing in at 160kg!
This isn’t a machine that you can expect to have access to, so in the meantime, we have to stick to our smaller machines.
Not all is bad because we have the ability to divide models into smaller parts, print those separately, then combine them together after with an adhesive substance like superglue or epoxy.