While today I can print almost everything imaginable, that wasn’t the case a few years ago when I first got into 3D printing. The standard filaments offered great workability and product quality, however, they only had a limited range of uses. Luckily, flexible filaments soon arrived on the marked and changed the future of 3D printing by broadening the range of objects that can be produced. One such filament is the popular TPU.
TPU stands for Thermoplastic Polyurethane and is a type of elastic polymer which you can use on any properly equipped 3D. TPU filaments are currently the material of choice for printing a variety of objects that need to bend or flex such as footwear, inflatable rafts, sporting goods, or cases for mobile devices. But TPU wasn’t the first flexible filament on the market. Its ancestor Thermoplastic Elastomer (TPE) used to be the preferred material for printing flexible objects. However, and I say this from experience, TPE is incredibly difficult to work with due to its softness and shore hardness of only 85A.
With a higher shore hardness of 94A, TPU filaments are the newer and improved alternative to TPE filaments. Because TPU is firmer, the 3D printing extruder can handle it a lot easier as opposed to TPE. This means that when using a TPU 3D filament, the risk of jamming or other printing complications appearing is significantly reduced. The resulting product is an ideal combination of elasticity, flexibility and rigidity.
Apart from being the best material for printing flexible objects, TPU is also superior in many ways to the standard filaments such as ABS and PLA. It has a high abrasion resistance which results in objects that are more durable. What’s more, TPU keeps its elastic properties even in very low temperatures, which means you don’t need to worry about it not performing in cold conditions. TPU 3D printing filament is also resistant to oils, greases, and a variety of solvents which makes it the preferred flexible 3D printing material for many industrial applications.
Of course, just like any material, TPU also has its challenges. When hot, TPU is very soft, so it’s recommended that the print is cooled as quickly as possible in order for it not to lose its shape. For this reason, it’s best to use a cooling fan at maximum speed. What’s more, all flexible filaments tend to easily absorb moisture from the environment. To preserve the quality of your TPU filament before printing you need to store it in an airtight container. Even so, it’s recommended that you dry it in an oven set to 90oC for 6 hours prior to printing. If there’s any amount of moisture in the filament, the result will be an object with marks and voids due to water bubbles evaporating.