TPU welding rod, or thermoplastic polyurethane welding rod, is used in applications requiring a flexible or elastomeric thermoplastic filler material. Unlike rigid welding plastics such as HDPE, PP or PVC, many TPU materials can remain highly flexible after cooling.
What Is TPU?
TPU stands for thermoplastic polyurethane. It is a family of thermoplastic elastomers that combines characteristics associated with rubber-like materials with the processing capability of a thermoplastic.
Depending on formulation and hardness, TPU can provide:
- Flexibility
- Elasticity
- Abrasion resistance
- Tear resistance
- Impact performance
- Wear resistance
- Thermoplastic processing
What Is TPU Welding Rod?
TPU welding rod is filler material manufactured from a thermoplastic polyurethane formulation for use with compatible TPU base materials.
Because TPU is thermoplastic, suitable grades can soften when heated and solidify again as they cool. This makes thermal joining possible for appropriate TPU materials.
TPU welding rod may also be described as:
- thermoplastic polyurethane welding rod
- TPU plastic welding rod
- TPU filler rod
- TPU welding wire
- flexible plastic welding rod
- flexible thermoplastic welding rod
- polyurethane welding rod
- plastic welding rod for TPU
TPU vs. Polyurethane Welding Rod
The terms TPU and polyurethane are sometimes used interchangeably in product descriptions, but there is an important distinction.
TPU specifically means thermoplastic polyurethane. It can be softened by heat and processed as a thermoplastic.
The broader polyurethane family also includes crosslinked or thermoset materials that do not behave like TPU when reheated.
Why TPU Welding Rod Is Different
TPU welding rod can behave very differently from rigid thermoplastic welding rod because TPU formulations span a wide range of hardness, elasticity and melt behavior.
Two TPU materials may both carry the TPU designation while having substantially different:
- Hardness
- Flexibility
- Melt behavior
- Chemical resistance
- Abrasion resistance
- Additive packages
- End-use performance
Matching the filler material to the base TPU is therefore important.
TPU Welding Rod Applications
Flexible Plastic Fabrication
TPU filler material can be used where the finished thermoplastic component needs flexibility rather than the stiffness of a rigid plastic.
Wear-Resistant Components
Certain TPU grades are selected for applications involving abrasion, wear and repeated flexing.
Flexible Plastic Repair
Compatible TPU components may be repairable using suitable thermoplastic welding procedures.
Industrial Components
TPU is used in specialty industrial components where elastomeric properties are required.
Custom Fabrication
TPU can be used in specialty fabricated products requiring flexibility and thermoplastic processing.
OEM Applications
OEM programs may require specific TPU grades, hardness, dimensions, colors and packaging.
TPU Welding Rod Hardness
One major characteristic used to distinguish TPU grades is hardness. TPU can be produced across a broad hardness range.
For welding applications, hardness can influence:
- Rod flexibility
- Feeding behavior
- Handling
- Melt response
- Finished weld flexibility
- Mechanical performance
A TPU filler rod with substantially different hardness or formulation from the base material may not provide the desired finished-joint properties.
TPU Welding Rod Sizes
TPU welding rod can be manufactured in several diameters and profiles, although the flexibility of a particular TPU grade can influence feeding, winding and welding behavior.
| Rod Profile | Size | General Description |
|---|---|---|
| Round | 3 mm | Smaller-diameter filler rod for suitable TPU applications. |
| Round | 4 mm | General-purpose size where compatible with the TPU grade and equipment. |
| Round | 5 mm | Larger filler profile for applications requiring additional material. |
| Custom | Application specific | Specialty profiles and dimensions for OEM or industrial requirements. |
See our complete Plastic Welding Rod Sizes Guide.
Round TPU Welding Rod
Round TPU welding rod can be produced for hot air and other suitable thermoplastic welding processes.
Because some TPU grades are considerably softer and more flexible than conventional rigid welding rod, equipment and feeding methods may need to be selected accordingly.
Flexible Plastic Welding Rod
People searching for flexible plastic welding rod are often looking for a filler that remains flexible after welding.
TPU is one possible thermoplastic family for flexible welding applications, but it is not appropriate for every flexible plastic.
Flexible PVC, certain polyethylene materials, TPU and other flexible thermoplastics are different material families. The welding rod should match the actual parent polymer.
How to Choose TPU Welding Rod
TPU filler selection should consider more than simply whether the material is flexible.
Consider:
- Confirmation that the material is TPU
- TPU resin grade
- Hardness
- Base chemistry or formulation when known
- Additives
- Color
- Rod diameter
- Rod profile
- Welding equipment
- Finished-joint flexibility
- Service environment
TPU vs. Flexible PVC Welding Rod
TPU and flexible PVC can both be soft and flexible, but they are different polymer families.
If the parent material is flexible PVC, select filler material compatible with that PVC formulation. See our PVC Welding Rod Guide.
If the parent material is TPU, select compatible thermoplastic polyurethane welding rod.
TPU vs. Polyethylene Welding Rod
Some polyethylene materials can also be flexible, particularly lower-density polyethylene grades.
That does not make polyethylene and TPU interchangeable.
For PE materials see our Polyethylene Welding Rod Guide.
TPU vs. Polypropylene Welding Rod
Polypropylene is generally much more rigid than soft TPU grades and belongs to a different polymer family.
For PP fabrication see Polypropylene Welding Rod.
How to Weld TPU
1. Identify the Material
Confirm that the parent material is a thermoplastic polyurethane rather than another flexible plastic or a thermoset polyurethane.
2. Identify the TPU Grade
When possible, obtain the resin grade, hardness and manufacturer information for the base material.
3. Select Compatible TPU Welding Rod
Choose filler material with suitable compatibility and properties for the parent TPU.
4. Clean the Welding Area
Remove oils, dirt, processing residue and other contamination that could interfere with fusion.
5. Prepare the Joint
Prepare the joint according to the material thickness, component geometry and welding process.
6. Select Suitable Equipment
Choose welding equipment and a nozzle that can properly handle the particular TPU rod and joint.
7. Establish Welding Conditions
Set appropriate heat and airflow and allow the welding tool to stabilize.
8. Heat the Weld Interface
Apply controlled heat to both the TPU base material and filler rod.
9. Apply Controlled Pressure
Feed the TPU rod into the joint while maintaining appropriate pressure and travel speed.
10. Cool and Inspect
Allow the welded material to cool before stressing the joint and inspect it for consistent fusion.
See our general How to Weld Plastic Guide.
Hot Air Welding TPU
Suitable TPU materials can be joined using controlled hot air welding. The process heats the filler rod and parent thermoplastic at the weld interface while pressure is applied.
Important variables include:
- TPU formulation
- Hardness
- Welding temperature
- Airflow
- Nozzle design
- Rod size
- Travel speed
- Pressure
Read our Hot Air Plastic Welding Guide.
TPU Welding Temperature
There is no single universal TPU welding temperature.
The TPU family includes many grades with different hardness levels, formulations and processing ranges. Welding conditions should be established for the specific material and equipment being used.
Factors include:
- TPU grade
- Hardness
- Material thickness
- Rod diameter
- Welding tool
- Airflow
- Nozzle geometry
- Travel speed
See our Plastic Welding Temperature Chart.
Why TPU Welding Rod Does Not Stick
Poor TPU fusion may be caused by:
- The parent material is not TPU
- The material is thermoset polyurethane
- Incompatible TPU formulations
- Contaminated surfaces
- Poor joint preparation
- Insufficient heat
- Excessive heat
- Incorrect airflow
- Travel speed that is too fast
- Insufficient pressure
- Improper welding technique
See Plastic Welding Troubleshooting.
TPU Welding Rod Colors
TPU welding rod can be manufactured in natural, black and custom colors depending on the particular resin, color concentrate and production requirements.
Color matching can be useful for visible welds, but the TPU formulation and compatibility should take priority over appearance alone.
Custom TPU Welding Rod
Industrial customers may require thermoplastic polyurethane welding rod manufactured from a particular TPU grade or to specific dimensional and packaging requirements.
Custom production can include:
- Customer-specified TPU grades
- Different hardness levels
- Natural TPU welding rod
- Black TPU welding rod
- Custom colors
- 3 mm round rod
- 4 mm round rod
- 5 mm round rod
- Specialty profiles
- Spool packaging
- Bulk packaging
- OEM production
- Distributor programs
- Private labeling
Learn more at Custom Plastic Welding Rod.
TPU Welding Rod Manufacturer
HotAirWelder.com is operated by New Image Plastics Manufacturing, a U.S. thermoplastic extrusion manufacturer with decades of plastic extrusion experience.
New Image Plastics manufactures TPU welding rod along with polyethylene, polypropylene, PVC, PVDF, PETG, ABS and other thermoplastic welding rod materials.
Production capabilities include round welding rod, specialty profiles, custom colors, spool packaging, custom extrusion and private-label or OEM manufacturing.
For manufacturer-direct information visit PlasticWeldingRod.com.
Frequently Asked Questions About TPU Welding Rod
What is TPU welding rod?
TPU welding rod is thermoplastic polyurethane filler material used to join compatible TPU materials.
Can TPU be welded?
Many TPU grades can be thermally welded because TPU is a thermoplastic. The welding process and filler material must be suitable for the particular grade.
Is TPU welding rod flexible?
TPU welding rod can be highly flexible, but flexibility depends on the particular TPU formulation and hardness.
Is TPU the same as polyurethane?
TPU is thermoplastic polyurethane. Polyurethane is a broader material category that also includes non-thermoplastic materials. A polyurethane part should therefore be identified before attempting thermoplastic welding.
Can I use flexible PVC welding rod on TPU?
Flexible PVC and TPU are different polymer families. Filler material should be selected for compatibility with the parent plastic.
What size TPU welding rod is available?
TPU welding rod can be manufactured in common round sizes such as 3 mm, 4 mm and 5 mm, as well as custom dimensions depending on the resin and application.
Can TPU welding rod be supplied on spools?
Suitable TPU welding rod can be wound onto spools, although the hardness and flexibility of the particular TPU grade can affect winding and handling.
Can TPU welding rod be custom colored?
Yes. Custom colors can be produced when compatible TPU resin and color concentrates are available.
Related Plastic Welding Guides
- Plastic Welding Rod
- Plastic Welding
- HDPE Welding Rod
- Polyethylene Welding Rod
- Polypropylene Welding Rod
- PVC Welding Rod
- PVDF Welding Rod
- ABS Welding Rod
- PETG Welding Rod
- Plastic Welding Rod Sizes
- Plastic Welding Temperature Chart
- How to Weld Plastic
- Hot Air Plastic Welding
- Plastic Welding Tools
- Plastic Welding Troubleshooting
Need TPU Welding Rod?
New Image Plastics Manufacturing produces thermoplastic polyurethane welding rod for industrial fabricators, distributors, OEMs and specialty applications.
Specific TPU grades, hardness levels, custom colors, round rod, specialty profiles and custom production programs can be evaluated depending on the application.
Phone: 330-854-3010
Email:
newimageplastics@sbcglobal.net