Bonding metal without welding: 5 high-performance adhesives compared
Metal joining without heat, distortion, or complex post-processing: Modern high-performance adhesives achieve shear strengths of up to 40 MPa and replace welding in numerous industrial applications. Choosing the right adhesive determines the strength, durability, and cost-effectiveness of the bond. This comparison presents the five most important adhesive systems for metal-to-metal bonding, including specific performance data, typical applications, and processing parameters.
Why glue metal instead of welding?
Adhesive bonds offer decisive technical and economic advantages over welded joints, which are increasingly being used in modern manufacturing.
Technical advantages:
- No thermal influence on the base material – no warping, no structural changes
- Joining of different metals without galvanic corrosion through an insulating layer
- Distributed force over a larger area instead of concentrated loads – better stress distribution
- The vibration-damping properties of the adhesive layer increase fatigue strength
- A way to join thin-walled components that cannot be welded
- No deformation of heat-sensitive structures
Economic advantages:
- Lower energy consumption – no high-temperature processes
- No welding specialists required – shorter training time
- Eliminating weld rework saves time and costs
- Automation and inline integration are easier to implement
- Lower investment costs for equipment
Typical industries and applications:
The automotive industry uses structural adhesives for body components, thereby reducing weight while simultaneously increasing rigidity. In mechanical engineering, housings, covers, and panels are bonded. The electronics industry relies on adhesives for EMC shielding and heat sink connections.
The decision to use adhesives is particularly common for mixed joints (steel-aluminium), thin sheets under 1 mm, painted surfaces, and when later disassembly is not important.
The 5 best types of adhesive for bonding metal
Epoxy resin adhesives (2K): The strength champions
Two-component epoxies offer the highest strengths of all structural adhesives and are suitable for highly stressed metal connections.
Typical products:
- Permabond ET5428: 2-component epoxy with 35-40 MPa shear strength on steel
- 3M Scotch-Weld DP490: Tough-elastic variant for vibration loads
Technical specifications:
- Shear strength: 25-40 MPa (depending on the system)
- Temperature resistance: -55°C to +150°C (standard), up to +200°C (special types)
- Gap bridging: 0.05-5 mm
- Cooking time: 5-90 minutes
- Curing time: 24 hours at 23°C (complete), accelerated at 60-80°C (2-4 hours)
- Mixing ratio: 1:1 to 10:1 (by weight or volume)
Processing:
Two-component systems require precise mixing. Use cartridges with static mixers or automatic dispensing systems for reproducible quality.
Ideal applications:
Structural bonding in mechanical engineering, fastening of threaded rods and bolts, repair of castings, composite metal connections.
Limitations:
Long curing times at room temperature, low flexibility (brittle fractures possible), mixing errors can reduce strength.
Methyl methacrylate (MMA): Fast and gap-filling
MMA-based structural acrylate adhesives combine high strength with excellent gap bridging and short curing times.
Typical products:
- Permabond TA4246: 2K-MMA with 22-26 MPa shear strength
- 3M Scotch-Weld DP8610: Low-odor variant
Technical specifications:
- Shear strength: 20-28 MPa
- Temperature resistance: -40°C to +120°C
- Gap bridging: 0.1-6 mm (excellent)
- Potting time: 3-8 minutes
- Handling resistance: 10-20 minutes
Ideal applications:
Joining hollow profiles, unclean or oily surfaces, uneven gap widths, bonding sandwich panels.
Polyurethane adhesives: The flexible all-rounders
Polyurethane systems offer the best balance between strength and flexibility – ideal for dynamically stressed joints.
Typical products:
- Teroson PU 9225: 1K moisture-curing compound for automotive body construction
- Sika Power 4720: 2K-PU with 18-22 MPa shear strength
Technical specifications:
- Shear strength: 12-22 MPa
- Elongation at break: 200-600% (highly elastic)
- Temperature resistance: -40°C to +100°C
Ideal applications:
vehicle bodies (crash strength), vibration-stressed connections, sandwich elements with different coefficients of expansion.
Cyanoacrylate: Fast to apply to small areas in seconds
Cyanoacrylate adhesives harden in seconds and are suitable for small bonding and fixing applications.
Typical products:
- Permabond 910: Universal CA for metals, 15-20 MPa
- Permabond 940: Toughened for impact-resistant connections
- Loctite 401: General-purpose CA for fast fixings
Technical specifications:
- Shear strength: 15-25 MPa
- Temperature resistance: -50°C to +80°C (standard), up to +120°C (HT types)
- Gap bridging: 0.05-0.15 mm (very small)
- Fixing time: 5-60 seconds
Anaerobic adhesives: Specialist for threads and joints
Anaerobic adhesives cure in the absence of air in metal crevices – perfect for screw locking and cylindrical joints.
Typical products:
- Loctite 243: Medium-strength threadlocker, removable
- Loctite 270: High-strength threadlocker
- Loctite 648: Adhesive for shaft-hub connections
Technical specifications:
- Shear strength: 15-28 MPa (depending on type and gap)
- Temperature resistance: -55°C to +150°C
- Gap range: 0.05-0.5 mm (optimal 0.1-0.15 mm)
Comparison table: An overview of the 5 adhesive types
| Characteristic | Epoxy (2K) | MMA (2K) | Polyurethan | cyanoacrylate | Anaerobic |
|---|---|---|---|---|---|
| Shear strength | 25-40 MPa | 20-28 MPa | 12-22 MPa | 15-25 MPa | 15-28 MPa |
| Max. temperature | 150-200°C | 120°C | 100°C | 80-120°C | 150°C |
| Gap bridging | 0.05-5 mm | 0.1-6 mm | 0.1-3 mm | 0.05-0.15 mm | 0.05-0.5 mm |
| Fixing time | 2-6 h | 10-20 min | 30-60 min | 5-60 sec | 10-30 min |
| flexibility | Low (brittle) | Medium | High (elastic) | Low (brittle) | Low |
| Components | 2K | 2K | 1K/2K | 1K | 1K |
| Best use | Maximum strength | Fast + Gap filling | flexibility | speed | Threads/shafts |
Selection aid:
- Maximum strength required → Epoxy
- Large/unequal column → MMA
- Vibration/Crash → Polyurethane
- Fastest fixing → cyanoacrylate
- Threads/cylindrical fits → Anaerobic
Surface preparation: The key to lasting adhesion
The strength of an adhesive bond depends 70% on the surface preparation.
Step 1: Cleaning
Remove all contaminants: Degrease with isopropanol or acetone. Wipe in one direction with lint-free cloths. Remove rust mechanically with a wire brush or by sandblasting.
Step 2: Mechanical Activation
Roughening the surface increases the active area: grinding with 80-120 grit sandpaper, sandblasting with 60-120 mesh corundum. Ideally, a roughness of Ra 3-10 μm.
Step 3: Primer (if required)
Primers improve adhesion to difficult surfaces such as stainless steel, aluminum, or coated metals. Typical primers include Permabond POP, Loctite 7649/7471, and Sika Activator.
Frequently Asked Questions (FAQ)
Conclusion: The right choice for any metal connection
Modern high-performance adhesives offer a technically and economically superior alternative to welding for virtually any metal joint.
Choose epoxy adhesives if you require maximum strength (up to 40 MPa) and temperature resistance up to 150°C.
Use methyl methacrylate for unequal gap widths and fast cycle times.
Use polyurethane systems for vibration-stressed structures and crash applications.
Use cyanoacrylate for quick fixes and small bonds.
Use anaerobic adhesives for threads, shaft-hub connections and tight metal gaps.
The success of any bonding process depends entirely on surface preparation – invest time in thorough cleaning and mechanical activation.
Get advice now: SILITECH adhesive technology expertise
Our application engineers will assist you in selecting the optimal adhesive system:
- Free technical advice on strength requirements
- Sampling with original products for your trials
- Processing training and process optimization
Bonding metal without welding: 5 high-performance adhesives compared
Metal joining without heat, distortion, or complex post-processing: Modern high-performance adhesives achieve shear strengths of up to 40 MPa and replace welding in numerous industrial applications. Choosing the right adhesive determines the strength, durability, and cost-effectiveness of the bond. This comparison presents the five most important adhesive systems for metal-to-metal bonding, including specific performance data, typical applications, and processing parameters.
Why glue metal instead of welding?
Adhesive bonds offer decisive technical and economic advantages over welded joints, which are increasingly being used in modern manufacturing.
Technical advantages:
- No thermal influence on the base material – no warping, no structural changes
- Joining of different metals without galvanic corrosion through an insulating layer
- Distributed force over a larger area instead of concentrated loads – better stress distribution
- The vibration-damping properties of the adhesive layer increase fatigue strength
- A way to join thin-walled components that cannot be welded
- No deformation of heat-sensitive structures
Economic advantages:
- Lower energy consumption – no high-temperature processes
- No welding specialists required – shorter training time
- Eliminating weld rework saves time and costs
- Automation and inline integration are easier to implement
- Lower investment costs for equipment
Typical industries and applications:
The automotive industry uses structural adhesives for body components, thereby reducing weight while simultaneously increasing rigidity. In mechanical engineering, housings, covers, and panels are bonded. The electronics industry relies on adhesives for EMC shielding and heat sink connections.
The decision to use adhesives is particularly common for mixed joints (steel-aluminium), thin sheets under 1 mm, painted surfaces, and when later disassembly is not important.
The 5 best types of adhesive for bonding metal
Epoxy resin adhesives (2K): The strength champions
Two-component epoxies offer the highest strengths of all structural adhesives and are suitable for highly stressed metal connections.
Typical products:
- Permabond ET5428: 2-component epoxy with 35-40 MPa shear strength on steel
- 3M Scotch-Weld DP490: Tough-elastic variant for vibration loads
Technical specifications:
- Shear strength: 25-40 MPa (depending on the system)
- Temperature resistance: -55°C to +150°C (standard), up to +200°C (special types)
- Gap bridging: 0.05-5 mm
- Cooking time: 5-90 minutes
- Curing time: 24 hours at 23°C (complete), accelerated at 60-80°C (2-4 hours)
- Mixing ratio: 1:1 to 10:1 (by weight or volume)
Processing:
Two-component systems require precise mixing. Use cartridges with static mixers or automatic dispensing systems for reproducible quality.
Ideal applications:
Structural bonding in mechanical engineering, fastening of threaded rods and bolts, repair of castings, composite metal connections.
Limitations:
Long curing times at room temperature, low flexibility (brittle fractures possible), mixing errors can reduce strength.
Methyl methacrylate (MMA): Fast and gap-filling
MMA-based structural acrylate adhesives combine high strength with excellent gap bridging and short curing times.
Typical products:
- Permabond TA4246: 2K-MMA with 22-26 MPa shear strength
- 3M Scotch-Weld DP8610: Low-odor variant
Technical specifications:
- Shear strength: 20-28 MPa
- Temperature resistance: -40°C to +120°C
- Gap bridging: 0.1-6 mm (excellent)
- Potting time: 3-8 minutes
- Handling resistance: 10-20 minutes
Ideal applications:
Joining hollow profiles, unclean or oily surfaces, uneven gap widths, bonding sandwich panels.
Polyurethane adhesives: The flexible all-rounders
Polyurethane systems offer the best balance between strength and flexibility – ideal for dynamically stressed joints.
Typical products:
- Teroson PU 9225: 1K moisture-curing compound for automotive body construction
- Sika Power 4720: 2K-PU with 18-22 MPa shear strength
Technical specifications:
- Shear strength: 12-22 MPa
- Elongation at break: 200-600% (highly elastic)
- Temperature resistance: -40°C to +100°C
Ideal applications:
vehicle bodies (crash strength), vibration-stressed connections, sandwich elements with different coefficients of expansion.
Cyanoacrylate: Fast to apply to small areas in seconds
Cyanoacrylate adhesives harden in seconds and are suitable for small bonding and fixing applications.
Typical products:
- Permabond 910: Universal CA for metals, 15-20 MPa
- Permabond 940: Toughened for impact-resistant connections
- Loctite 401: General-purpose CA for fast fixings
Technical specifications:
- Shear strength: 15-25 MPa
- Temperature resistance: -50°C to +80°C (standard), up to +120°C (HT types)
- Gap bridging: 0.05-0.15 mm (very small)
- Fixing time: 5-60 seconds
Anaerobic adhesives: Specialist for threads and joints
Anaerobic adhesives cure in the absence of air in metal crevices – perfect for screw locking and cylindrical joints.
Typical products:
- Loctite 243: Medium-strength threadlocker, removable
- Loctite 270: High-strength threadlocker
- Loctite 648: Adhesive for shaft-hub connections
Technical specifications:
- Shear strength: 15-28 MPa (depending on type and gap)
- Temperature resistance: -55°C to +150°C
- Gap range: 0.05-0.5 mm (optimal 0.1-0.15 mm)
Comparison table: An overview of the 5 adhesive types
| Characteristic | Epoxy (2K) | MMA (2K) | Polyurethan | cyanoacrylate | Anaerobic |
|---|---|---|---|---|---|
| Shear strength | 25-40 MPa | 20-28 MPa | 12-22 MPa | 15-25 MPa | 15-28 MPa |
| Max. temperature | 150-200°C | 120°C | 100°C | 80-120°C | 150°C |
| Gap bridging | 0.05-5 mm | 0.1-6 mm | 0.1-3 mm | 0.05-0.15 mm | 0.05-0.5 mm |
| Fixing time | 2-6 h | 10-20 min | 30-60 min | 5-60 sec | 10-30 min |
| flexibility | Low (brittle) | Medium | High (elastic) | Low (brittle) | Low |
| Components | 2K | 2K | 1K/2K | 1K | 1K |
| Best use | Maximum strength | Fast + Gap filling | flexibility | speed | Threads/shafts |
Selection aid:
- Maximum strength required → Epoxy
- Large/unequal column → MMA
- Vibration/Crash → Polyurethane
- Fastest fixing → cyanoacrylate
- Threads/cylindrical fits → Anaerobic
Surface preparation: The key to lasting adhesion
The strength of an adhesive bond depends 70% on the surface preparation.
Step 1: Cleaning
Remove all contaminants: Degrease with isopropanol or acetone. Wipe in one direction with lint-free cloths. Remove rust mechanically with a wire brush or by sandblasting.
Step 2: Mechanical Activation
Roughening the surface increases the active area: grinding with 80-120 grit sandpaper, sandblasting with 60-120 mesh corundum. Ideally, a roughness of Ra 3-10 μm.
Step 3: Primer (if required)
Primers improve adhesion to difficult surfaces such as stainless steel, aluminum, or coated metals. Typical primers include Permabond POP, Loctite 7649/7471, and Sika Activator.
Frequently Asked Questions (FAQ)
Conclusion: The right choice for any metal connection
Modern high-performance adhesives offer a technically and economically superior alternative to welding for virtually any metal joint.
Choose epoxy adhesives if you require maximum strength (up to 40 MPa) and temperature resistance up to 150°C.
Use methyl methacrylate for unequal gap widths and fast cycle times.
Use polyurethane systems for vibration-stressed structures and crash applications.
Use cyanoacrylate for quick fixes and small bonds.
Use anaerobic adhesives for threads, shaft-hub connections and tight metal gaps.
The success of any bonding process depends entirely on surface preparation – invest time in thorough cleaning and mechanical activation.
Material question still open?
Whether sealing, potting or bonding – when the application is critical, the choice of material is not a minor matter.
Discuss the application →Further information
- Permabond adhesives: product range, technical data & Loctite comparison
- Loctite 5910: Silicone flange gasket (FIPG)
- Loctite 638: High-strength shaft-hub connection
- Selecting and correctly using screw locking devices
- Industrial adhesives compared: epoxy, cyanoacrylate, anaerobic, UV, MMA. Which adhesive for which application?
- Structural adhesives in the shop
- Request technical advice
