Optimizing the Bonding of Friction Linings on Steel and Aluminum Brake Systems with Araldite® 71
Bonding friction linings is a critical operation in the manufacturing and maintenance of braking systems, particularly in the railway, automotive, and heavy industry sectors. This technique ensures a strong and durable link between friction pads (or other braking elements) and their metallic support, often made of steel or aluminum. In such demanding environments, selecting the right adhesive is crucial to ensure performance, safety, and system longevity.
Among the available options on the market, Araldite 71 stands out as a trusted reference. Developed by Huntsman, this vinyl-phenolic-based adhesive is specifically designed to meet the mechanical, thermal, and chemical demands of friction bonding applications.
Understanding Friction Lining Bonding: A Major Technical Challenge
Friction lining bonding involves attaching a wear-resistant composite material to a metal backing, ensuring efficient braking force transfer. This method is widely used across industries where braking reliability is paramount: rail transport, utility vehicles, elevators, machine tools, etc.
Compared to mechanical fastening (rivets, bolts), bonding offers several advantages:
- Even load distribution across the bonded area
- Noise and vibration reduction
- System weight reduction by eliminating metal fixtures
- Enhanced safety through improved thermal stability
Choosing the right adhesive guarantees:
- Excellent adhesion to steel and aluminum
- High resistance to elevated temperatures during braking
- Robust performance against humidity and vibrations
- Increased durability of the braking system
Brake Lining Bonding: Requirements and Constraints
Brake lining bonding must withstand particularly harsh technical conditions, especially in railway and industrial applications. During operation, materials are exposed to:
- Very high temperatures (exceeding 300 °C)
- Cyclic mechanical loads (pressure, shear)
- Humid, dusty, or corrosive environments
- Frequent braking cycles and thermal shocks
Therefore, the adhesive must:
- Resist mechanical stress and shear
- Maintain adhesion at high temperatures
- Withstand oxidation and humidity over time
- Allow reproducible application in industrial settings
This is where Araldite 71 truly excels.
Araldite 71: A Technical Adhesive for Friction Lining Applications
Araldite 71 is a single-component, vinyl-phenolic-based adhesive designed specifically for bonding friction linings to metal substrates (steel, aluminum, etc.). It has a thixotropic, paste-like consistency, ideal for controlled application—even on vertical surfaces.
Key Technical Characteristics:
| Property | Value |
|---|---|
| Type | Single-component vinyl-phenolic resin |
| Viscosity | Thixotropic (paste) |
| Solids content (at 160 °C) | 47–51% |
| Density | 1.002 g/cm³ |
| Flash point | 13 °C |
| Curing temperature | 160–200 °C depending on the cycle |
These properties make Araldite 71 easy to apply (roller, extrusion, manual or automated systems) and ensure long-term performance under extreme conditions.
Why Choose Araldite 71 for Brake Lining Bonding?
Choosing the right adhesive is vital for critical components like brakes. Here’s why Araldite 71 is the go-to solution:
1. Outstanding adhesion on steel and aluminum
Formulated for optimal chemical and mechanical bonding on metals, including treated or anodized surfaces.
2. High thermal resistance
Withstands continuous exposure up to 200 °C and peak temperatures up to 300 °C. Ideal for demanding braking cycles.
3. Chemical and humidity resistance
Performs reliably in environments with oils, grease, cleaning agents, vapor, salt, and moisture.
4. Dimensional stability
Remains structurally sound despite thermal shock and vibration.
5. Easy and precise application
Its thixotropic texture enables neat deposition, compatible with robotic or manual processes.
Araldite 71 vs. Other Industrial Adhesives
Here’s a comparison of Araldite 71 with other common adhesive technologies:
| Criteria | Araldite 71 | Epoxy Adhesives | Polyurethane | Acrylic |
| Max Temperature | Up to 300 °C | 120–180 °C | 80–120 °C | 100–140 °C |
| Chemical Resistance | Excellent | Good | Moderate | Moderate |
| Metal Adhesion | Excellent | Good | Average | Variable |
| Industrial Application | Easy | May require mixing | Easy | Quick but odorous |
| Durability | Very High | High | Medium | Medium |
| Cost | Medium-High | Medium-High | Medium | Low |
Conclusion: For brake lining bonding, where temperature and load performance are key, Araldite 71 offers unmatched reliability in industrial settings.
Industrial Applications of Araldite 71
Araldite 71 is widely used in:
🚄 Railway sector
- Bonding brake pads in high-speed trains, metros, trams
- Resists thermal cycling, humidity, and vibrations
🚛 Commercial and heavy-duty vehicles
- Bonding of brake linings on trucks and buses
- Improves fatigue resistance, reduces noise and weight
🏗️ Heavy machinery and tools
- Brakes for cranes, presses, elevators, industrial winches
- Ideal for abrasive and dusty environments
Application Guide for Araldite 71
For optimal bonding performance, follow these steps:
1. Surface Preparation
- Degrease with non-chlorinated solvent
- Light sanding or grit blasting to enhance adhesion
- Final clean with isopropyl alcohol
2. Adhesive Application
- Apply with roller or spatula (manual or automated)
- Recommended thickness: 100–200 µm
- Assemble immediately or within 30 minutes
3. Assembly & Pressure
- Apply moderate pressure (0.2–0.5 MPa)
- Temporary clamping may be used
4. Curing
- Standard cycle: 160 °C for 30 minutes
- Adjust based on part geometry/material (refer to datasheet)
5. Quality Control
- Visual inspection of bond line
- Peel or shear test (optional)
Why Engineers Trust Araldite 71
Araldite 71 delivers the ideal balance between performance and processability:
✅ High thermal resistance
✅ Long-term reliability
✅ Compatible with fast-paced production lines
✅ Reduces maintenance and downtime
It is widely adopted by railway operators, brake manufacturers, and design offices looking for robust and proven bonding solutions.
Final Thoughts
Bonding friction linings is a critical safety operation. With its exceptional technical profile, Araldite 71 is the trusted adhesive for demanding applications where heat, pressure, and reliability matter.
As a distributor of Huntsman’s Araldite® range, Samaro supports manufacturers, maintenance teams, and R&D departments in selecting and implementing the best bonding solutions.
❓FAQ – All You Need to Know About Araldite 71 and Friction Bonding
🔹 How is Araldite 71 different from regular epoxy adhesives?
Araldite 71 is a vinyl-phenolic resin, offering superior heat resistance and mechanical strength—perfect for high-stress braking systems.
🔹 Can it be used on anodized aluminum?
Yes. Araldite 71 adheres well to various metals, including anodized, blasted, or pre-treated surfaces.
🔹 Is it suitable for humid or marine environments?
Absolutely. It withstands humidity, salt spray, and occasional immersion.
🔹 What’s the shelf life?
Several months at room temperature. Refrigerated storage extends shelf life—refer to technical data sheet.
🔹 What is the recommended cure cycle?
160 °C for 30 minutes. Can be adjusted depending on part thickness and geometry.
🔹 Can it be used in automated production?
Yes. Its thixotropic paste texture allows precise dispensing in automated lines.