How to Weld TPU Filament

If you have a 3D printing project to work on and need a material that is abrasion resistant, has low-temperature flexibility, and remarkable mechanical properties, TPU is what you need. It is the right choice for anyone who requires thermoplastic rubbers, otherwise called thermoplastic elastomer (TPE), with flexible and low-temperature features.

Perhaps you may be wondering what I mean by TPU. Here, you’ll learn what that means and how it can be welded to make a perfect 3D print.

TPU is short for Thermoplastic Polyurethane. It refers to any class of polyurethane plastic with many properties. Some of these properties include transparency, elasticity, and resistance to grease, oil, and abrasion. Thus, they are suitable for transparent prints that are also elastic.

TPE, on the other hand, refers to thermoplastic elastomer, also called thermoplastic rubbers. They are a class of copolymers usually made from a mixture of plastic and rubber with both thermoplastic and elastomeric properties. TPU is, therefore, a type of TPE.

Not all 3D prints done with TPU requires welding, but when you’re working on complicated prints like the Batman helmet piece or Batman chest piece, you’ll have to print the parts separately, which will be attached to form a single body. The question now is, how can you merge all these parts such that they don’t get detached easily? The answer is welding. If well done, welding provides firm attachments making your print joints very difficult to separate even by applying strong force.

The filament used in this tutorial was gotten from Zyltech. Save 15% off your filament with Zyltech! - Use the code “nikkoindustries” at check out!

Now that you understand what TPU and TPE mean, we should hit the nail on the head and go straight to the tutorial of “How to weld your separate TPU materials together.”

For a better understanding, this tutorial has been split into different parts, including:

Part One: Attaching the different parts

Part Two: Soldering

Part Three: Filament melting

Part Four: Confirm the firmness

Part One: Attaching the different parts

Step 1: The first thing you should do is bring the different parts together, one at a time. Hold them together and ensure they are well aligned.

Step 2: Use a masking tape to hold together parts to be welded. Ensure that the parts are closely held together, and the tape is at the non-welding side. This means if you want to weld the front, you will tape the back and vice versa. The tape helps to keep the parts intact.

Thus, you don’t need a third party to hold the parts for you while you weld. With a masking tape, you can do the welding alone.

Part Two: Soldering

Step 1: Plug your soldering iron until it turns red hot (no particular temperature as long as it is obviously hot) just as you’ll do for your usual soldering. You can use a flat tip soldering iron or the chisel tip one, depending on your convenience or what is available.

Step 2: Make a trench with the soldering iron right at the joints. This will melt the joint and creates a space for the filament to sit. Ensure you melt the joint from up down to make a smooth area. Check if there’s an area without enough space for the filament to sit. If there’s any, you should make space by soldering.

Part Three: Filament melting

3D printing filament is a thermoplastic material used for fused deposition modeling 3D printers. In simpler terms, 3D filaments are a single fibril made of natural or synthetic textile fiber. They are fine and tiny with indefinite length, sometimes several miles long. They are often required for 3D printing.

There are different colors from which you can choose depending on what matches your print work. For instance, you can use a black filament for a black print. Other available colors include green, yellow, pink, white, purple, red, blue, orange, brown, etc.

There are also different filament types you can use, depending on the properties you desire. Each type has a unique melting temperature.

Filament, in this case, is meant to serve the function of lead used for wire soldering. It’ll be melted to fill the gap between the joints and keep them intact. The steps required for filament melting include:

Step 1: Place the filament in the space you created at the joint with the soldering iron.

Step 2: Hold the filament close to where you want to solder to keep it in place and begin soldering.

Step 3: Gently melt the filament to fill the gap. This will help make the super-strong bond you need to keep the different parts of your TPU together. Most people prefer to use the flat tip soldering iron because it gives a smoother weld.

Part Four: Confirm the firmness

It’s not enough to weld your TPU without checking whether you’ve done an excellent job or not. You need to confirm whether the joint is well glued together, so it doesn’t detach at any unexpected time. However, don’t try to test the firmness immediately after soldering. What you’ll get in such a case is a detached TPU. Instead, you should leave the TPU till it cools down.

When it cools, the melted filament would have solidified and firmer. This is when you should carry out your firmness confirmation test. It is a simple physical test that should be performed by holding the welded TPU on two different edges. Exert force like you want to pull it apart. Start with a soft pull, and progress gradually to harder pulls.

If it is well soldered, and the spaces are all filled with filament, it’ll remain intact and will not detach even when you pull harder. This confirms that you’ve done an excellent job, and you’ve successfully welded your TPU.