Timing Belt Materials and Tension Members
Timing Belt Materials and Tension Members
Selecting the right polyurethane compound and tension member is critical to timing belt performance and service life. Texas Belting offers a comprehensive range of materials engineered for specific operating conditions including food contact, chemical exposure, temperature extremes, anti-static requirements, and UV resistance. This guide covers all available polyurethane compounds and tension member options.
For information on chemical compatibility of these materials, see the chemical resistance guide. For food-grade material selection specifically, see the FDA food-grade timing belts page. For high-temperature applications, see Redflex GEN III.
- 7 general-purpose compounds (ST, N, B, SM series)
- 5 FDA food-grade compounds (FDA, AU series)
- 4 specialty compounds (low-temp, high-temp, anti-static)
- 4 tension member types (steel, stainless, sealed, aramid)
- Temperature range: -30°C to +80°C standard (+100°C GEN III)
- Hardness range: 85 to 95 Shore A
- All materials available across T, AT, and ATP profiles
- Certificates of compliance available on request
General-Purpose Polyurethane Materials
These are the standard compounds for industrial timing belt applications. TPU ST1 (92 Shore A) is the most commonly specified grade and is suitable for the majority of power transmission and conveying applications.
| Material | Color | Hardness | Key Features |
|---|---|---|---|
| TPU ST1 | White | 92 Shore A | Standard grade, most common for general industrial use |
| TPU ST2 | White | 85 Shore A | Softer compound for applications needing more flexibility |
| TPU ST3 | White | 95 Shore A | Harder compound, increased wear and abrasion resistance |
| TPU N1 | Black | 92 Shore A | UV resistant for outdoor and exposed environments |
| TPU N2 | Black | 85 Shore A | UV resistant, softer compound |
| TPU B1 | Blue | 92 Shore A | Color-coded identification (non-FDA blue) |
| TPU SM1 | White | 92 Shore A | Enhanced compound for specific performance applications |
Food-Grade Materials (FDA 21 CFR)
These compounds comply with FDA 21 CFR 177.2600 and EU Regulation 10/2011 for food contact. For detailed food-grade material selection guidance, see the FDA food-grade timing belts page.
| Material | Color | Hardness | Hydrolysis Resistance | Best For |
|---|---|---|---|---|
| TPU FDA1 | Clear | 92 Shore A | Low | Food grade, dry contact applications |
| TPU FDA2 | Clear | 85 Shore A | Low | Food grade, dry contact, softer compound |
| TPU AU1 | Clear | 92 Shore A | High | Food grade, continuous washdown rated |
| TPU AU2 | Clear | 95 Shore A | High | Food grade, washdown, high abrasion resistance |
| TPU AU3 | Gray | 86 Shore A | Low | Resistant to oils, fats, and greases |
Specialty Materials
| Material | Type | Key Features | Typical Applications |
|---|---|---|---|
| TPU KF1 / KF2 | Low temperature | Maintains flexibility below -30°C | Frozen food, cold storage, outdoor winter |
| TPU WB | High temperature | Extended operating range above +80°C | Near ovens, dryers, heat-treating equipment |
| TPU AS1 | Anti-static | Dissipates static charge (10⁶ to 10⁹ ohm) | Semiconductor, electronics, cleanroom |
| TPU AS7 | Anti-static (enhanced) | Lower surface resistivity for higher discharge rate | ESD-sensitive assembly, chip handling |
For high-performance applications requiring both elevated temperature resistance and enhanced flex life, the Redflex GEN III compound operates continuously to +100°C with up to 50% longer flex fatigue life than standard polyurethane.
Tension Member Options
The tension member is the load-bearing core of the belt. Selecting the right cord type affects tensile strength, elongation, corrosion resistance, and magnetic properties.
| Tension Member | Corrosion Resistance | Relative Strength | Key Features |
|---|---|---|---|
| High-carbon steel cord | Low | 100% (baseline) | Standard cord, best stiffness and tensile strength |
| Stainless steel cord | High | ~80% | Corrosion resistant for wet and chemical environments |
| Sealed steel (AU1 encapsulated) | High | 100% | Steel cords sealed in AU1 polyurethane for full washdown |
| Aramid (Kevlar) cord | High | ~60% (with more elongation) | Non-metallic, non-magnetic, lightweight |
Material Selection Quick Guide
| Application Condition | Recommended Compound | Recommended Cord |
|---|---|---|
| General industrial drives | TPU ST1 (92 Shore A) | High-carbon steel |
| Outdoor or UV exposure | TPU N1 or N2 (black) | High-carbon steel |
| Dry food contact | FDA1 or FDA2 | Stainless steel |
| Wet food processing / washdown | AU1 or AU2 | Sealed steel or stainless |
| Oil and grease exposure | TPU AU3 | Stainless steel |
| Electronics / anti-static | TPU AS1 or AS7 | Aramid (non-magnetic) |
| Freezer / cold storage | TPU KF1 or KF2 | High-carbon or stainless steel |
| High temperature (above 80°C) | GEN III or TPU WB | High-carbon steel |
| Wet / corrosive (non-food) | TPU ST1 | Stainless steel |
| MRI / non-magnetic required | Any standard compound | Aramid (Kevlar) |
Frequently Asked Questions
Texas Belting offers 16 polyurethane compounds across three categories: general-purpose (ST1, ST2, ST3, N1, N2, B1, SM1), FDA food-grade (FDA1, FDA2, AU1, AU2, AU3), and specialty (KF1, KF2, WB, AS1, AS7). Additionally, the Redflex GEN III high-performance compound is available for demanding high-speed and high-temperature applications.
Four tension member types are available: high-carbon steel cord (standard, highest strength), stainless steel cord (corrosion resistant, ~80% of standard strength), sealed steel with AU1 encapsulation (full washdown capability with full steel strength), and aramid/Kevlar cord (non-metallic, non-magnetic, ~60% strength with more elongation). Each belt uses a single tension member type.
Standard polyurethane compounds operate from -30°C to +80°C. GEN III compounds extend the upper limit to +100°C continuous. Low-temperature compounds (KF1, KF2) maintain flexibility below -30°C for frozen food and cold storage applications. For specific temperature limits by compound, contact Texas Belting at 888-203-2358.
TPU (thermoplastic polyurethane) is used for standard extruded and injection-molded belts. AU (cast polyurethane) compounds offer superior mechanical properties including higher tear strength, better abrasion resistance, and improved dynamic performance. AU compounds are also hydrolysis-resistant, making them the correct choice for washdown and wet environments. AU1 and AU2 are both FDA food-grade and washdown rated.
Yes. FDA1 and FDA2 comply with FDA 21 CFR 177.2600 and EU Regulation 10/2011 for food contact. AU1 and AU2 are both FDA-compliant and washdown rated. When combined with stainless steel or sealed steel tension members, these belts are fully suitable for food processing and pharmaceutical applications. See the FDA food-grade page for detailed selection guidance.
The standard hardness is 92 Shore A (TPU ST1), suitable for most applications. Use 85 Shore A (ST2, N2, FDA2) for applications needing more flexibility or cushioning. Use 95 Shore A (ST3, AU2) for applications requiring maximum wear and abrasion resistance. Contact Texas Belting at 888-203-2358 if you are unsure which hardness is right for your application.
Standard polyurethane can generate static charge during operation. For semiconductor, electronics, and ESD-sensitive applications, specify anti-static compounds (AS1 or AS7) paired with aramid tension members. These compounds dissipate static charge to prevent damage to sensitive components or electrostatic discharge events.
Polyurethane timing belts stored in cool, dry conditions away from direct sunlight have a practically unlimited shelf life. Unlike rubber belts that degrade through ozone cracking and oxidation during storage, polyurethane does not deteriorate. Belts stored for years will perform identically to newly manufactured belts.
Need Help Selecting the Right Material?
Send us your application details including temperature, chemical exposure, food contact requirements, and operating conditions. We will recommend the best compound and tension member combination.