In the latest of our regular series, we look at not one but two materials that aren't those you'd automatically choose: TPU and TPE.
In the earlier parts of the series we've looked at the most popular and commonly used types of filament for FDM 3D printing. TPU and TPE are lesser used materials but those that have a multitude of uses.
We'll take a look at some of those uses, the pros and cons of using TPU and TPE as well as some examples of actual 3D printed items. First though, let's look at what both TPU and TPE are and their properties.
What are TPU and TPE?
TPU or Thermoplastic Polyurethane is a flexible material with similar properties to those of silicone or rubber. TPE or Thermoplastic Elastomer is part of the same material "family" but with a slightly different chemical composition.
These are both types of flexible filaments that are known are known for their elasticity allowing them to easily stretch and bend. They’ve been grouped together as they have very similar properties and working parameters.
These working parameters however do make flexible filaments a bit tricky to print with as you need to get the bed adhesion just right to allow it to stick but then come off the print bed undamaged.
What can they be used for?
These filaments are ideal for making flexible parts in machinery, such as grommets and gear belts but also lend themselves well to toys and similar items. Going back to our friend Lego, they use flexible materials such as these for making the tyres on vehicles etc. More recently, you may have seen flexible filaments used to print full sized, wearable shoes as well as prototypes for production line trainers.
Pros and Cons
Flexible and soft
Difficult to print
Excellent vibration dampening
Poor bridging characteristics
Long shelf life
Possibility of nozzle clogs and other issues
Good impact resistance
May not work well on Bowden extruders
While TPU and TPE have similar characteristics they obviously both have a slightly different chemical makeup. Therefore, not all applications work well with both materials so there are things that one is more suitable for than the other.
TPU - As mentioned above, flexible materials such as TPU are commonly used in machinery. The nature of TPU makes it flexible but at the right density it can also have a certain rigidity. It can therefore be used both for drive belts in machinery as well as for the covers if necessary.
TPE - Again, TPE could be used for drive belts and covers but this would be where much more flexibility is needed. Outdoor machinery where control panels and switches are open to the elements benefit from having a flexible and possible transparent cover made from TPE.
TPU - TPU has uses in the automotive industry and although it's not as common as say ABS, it can be used for instrument panels, gear knobs, consoles and other interior parts in vehicles.
TPE - The use of TPE in the automotive industry relies on it's increased flexibility over it's TPU counterpart. Things like tires, door seals and window seals are ideally suited to the material.
TPU - Items such as cell phones, handheld consoles or other portable electrical devices need protection against being dropped or receiving impact. TPU is the ideal material for such device covers as it offers strength as well as flexibility
TPE - If we look again at these covers, you've probably seen the option of having them in a far more flexible material. Often these are referred to under the banner heading of silicone but are usually made from TPE.
3D Printing Uses
As we've seen, both TPU and TPE can be used in a variety of situations where a certain about of flexibility is needed while still providing strength and protection.
The uses in 3D printing would therefore be very similar but maybe on a smaller scale in some cases. For instance, you can 3D print a cell phone case which is usable and manufacturers are in fact using the technology more and more for things like this.
Toys are another area where 3D printing could be used with TPU or TPE. Things like fidget toys, stress balls, character figures etc. are things that can be 3D printed due to their inherent small sizes. If we also look at Lego again, vehicle tires and other mini, flexible components can be 3D printed. This isn't how Lego makes their parts but you could 3D print replacements or design your own version of a Lego model.
Obviously, 3D printing of prototypes can be done using TPU and TPE if needed and in the case of machine prototyping, the material would then be the same as the drive belts, seals and grommets used in the final product.
As we've seen, both TPU and TPE are flexible FDM 3D printing materials that have many uses.
While each of these materials fall under the same umbrella in terms of their basic chemical makeup, they have individual and distinctly different properties that make their uses more adaptable and versatile.
3D printing using these materials does have its difficulties but if used under the right parameters and for the right purpose, the results can be exceptional.