Bonding metal without welding: 5 high-performance adhesives compared
Metal joints without heat, distortion, or costly post-processing: Modern high-performance adhesives achieve shear strengths of up to 40 MPa and are replacing welding in numerous industrial applications. The right choice of adhesive determines the load-bearing capacity, durability, and cost-effectiveness of the bond. This comparison shows you the five most important adhesive systems for metal-to-metal bonding with specific performance data, typical areas of application, and processing parameters.
Why glue metal instead of welding it?
Compared to welded joints, adhesive bonds offer decisive technical and economic advantages that are increasingly being exploited in modern manufacturing.
Technical advantages:
- No thermal influence on the base material – no warping, no structural changes
- Joining different metals without galvanic corrosion thanks to an insulating layer
- Flat force application instead of point loading – better stress distribution
- Vibration-damping properties of the adhesive layer increase fatigue strength
- Possibility of joining thin-walled components that cannot be welded
- No deformation of heat-sensitive structures
Economic advantages:
- Lower energy consumption – no high-temperature processes
- No skilled welders required – shorter training period
- Eliminating weld seam finishing saves time and money
- Automation and inline integration easier to implement
- Lower investment costs for equipment
Typical industries and applications:
The automotive industry uses structural adhesives for car body components, thereby reducing weight while increasing rigidity. In mechanical engineering, housings, covers, and panels are bonded. The electronics industry relies on bonding for EMC shielding and heat sink connections.
Adhesives are the preferred choice for mixed joints (steel-aluminum), thin sheets under 1 mm, painted surfaces, and when subsequent disassembly is not an issue.
The 5 best types of adhesive for bonding metal
Epoxy resin adhesives (2K): The strength champions
Two-component epoxies provide the highest strength of all structural adhesives and are suitable for heavy-duty metal joints.
Typical products:
- Permabond ET5428: 2K epoxy with 35-40 MPa shear strength on steel
- 3M Scotch-Weld DP490: Tough, elastic variant for vibration loads
Technical characteristics:
- 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
- Pot life: 5-90 minutes
- Curing: 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 dosing systems for reproducible quality.
Ideal applications:
Structural bonding in mechanical engineering, fastening threaded rods and bolts, repairing 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
Structural acrylic adhesives based on MMA 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 characteristics:
- Shear strength: 20-28 MPa
- Temperature resistance: -40°C to +120°C
- Gap bridging: 0.1-6 mm (excellent)
- Pot life: 3-8 minutes
- Handling strength: 10-20 minutes
Ideal applications:
Joining hollow profiles, dirty 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 loaded connections.
Typical products:
- Teroson PU 9225: 1K moisture-curing adhesive for car body construction
- Sika Power 4720: 2K-PU with 18-22 MPa shear strength
Technical characteristics:
- Shear strength: 12–22 MPa
- Elongation at break: 200-600% (highly elastic)
- Temperature resistance: -40°C to +100°C
Ideal applications:
Vehicle bodies (crash resistance), vibration-stressed connections, sandwich elements with different expansion coefficients.
Cyanoacrylate: In seconds for small areas
Cyanoacrylate adhesives cure in seconds and are suitable for small bonding and fixing applications.
Typical products:
- Permabond 910: Universal CA for metals, 15-20 MPa
- Permabond 940: Toughness modified for impact-loaded joints
- Loctite 401: All-purpose CA for quick fixes
Technical characteristics:
- 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 low)
- Fixing time: 5-60 seconds
Anaerobic adhesives: Specialists for threads and joints
Anaerobic adhesives cure in metal gaps when exposed to air – perfect for securing screws and cylindrical connections.
Typical products:
- Loctite 243: Medium-strength threadlocker, removable
- Loctite 270: High-strength threadlocker
- Loctite 648: Bonding agent for shaft-hub connections
Technical characteristics:
- Shear strength: 15-28 MPa (depending on type and gap)
- Temperature resistance: -55°C to +150°C
- Gap range: 0.05–0.5 mm (optimum 0.1–0.15 mm)
Comparison table: An overview of the 5 types of adhesive
| property | Epoxy (2K) | MMA (2K) | polyurethane | cyanoacrylate | anaerobic |
|---|---|---|---|---|---|
| shear strength | 25–40 MPa | 20–28 MPa | 12-22 MPa | 15–25 MPa | 15–28 MPa |
| Maximum temperature | 300-370°F | 120°C | 100°C | 162–248°F | 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 hours | 10-20 min | 30-60 min | 5-60 seconds | 10-30 min |
| flexibility | Low (brittle) | means | High (elastic) | Low (brittle) | Low |
| components | 2K | 2K | 1K/2K | 1K | 1K |
| Best application | Highest strength | Fast + gap filling | flexibility | speed | Threads/shafts |
Selection guide:
- Maximum strength required → Epoxy
- Large/uneven gap → MMA
- Vibration/Crash → Polyurethane
- Fastest fixation → Cyanoacrylate
- Threaded/cylindrical fits → Anaerobic
Surface preparation: The key to lasting adhesion
The strength of an adhesive bond depends 70% on surface preparation.
Step 1: Cleaning
Remove all contaminants: Remove grease with isopropanol or acetone. Wipe in one direction with lint-free cloths. Remove rust mechanically with a wire brush or sandblasting.
Step 2: Mechanical activation
Roughening the surface increases the active area: sanding with 80-120 grit, sandblasting with corundum 60-120 mesh. Ideally, roughness Ra 3-10 μm.
Step 3: Primer (if needed)
Primers improve adhesion on difficult surfaces such as stainless steel, aluminum, or coated metals. Typical primers: Permabond POP, Loctite 7649/7471, Sika Aktivator.
Frequently asked questions (FAQ)
Conclusion: The right choice for every metal connection
Modern high-performance adhesives offer a technically and economically superior alternative to welding for virtually any metal joint.
Choose epoxy resin adhesives if you require maximum strength (up to 40 MPa) and temperature resistance up to 150°C.
Rely on methyl methacrylate for uneven gap widths and fast cycle times.
Use polyurethane systems for structures subject to vibration and crash applications.
Use cyanoacrylate for quick fixes and small bonding jobs.
Use anaerobic adhesives for threads, shaft-hub connections, and tight metal gaps.
The success of any bonding process depends 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 joints without heat, distortion, or costly post-processing: Modern high-performance adhesives achieve shear strengths of up to 40 MPa and are replacing welding in numerous industrial applications. The right choice of adhesive determines the load-bearing capacity, durability, and cost-effectiveness of the bond. This comparison shows you the five most important adhesive systems for metal-to-metal bonding with specific performance data, typical areas of application, and processing parameters.
Why glue metal instead of welding it?
Compared to welded joints, adhesive bonds offer decisive technical and economic advantages that are increasingly being exploited in modern manufacturing.
Technical advantages:
- No thermal influence on the base material – no warping, no structural changes
- Joining different metals without galvanic corrosion thanks to an insulating layer
- Flat force application instead of point loading – better stress distribution
- Vibration-damping properties of the adhesive layer increase fatigue strength
- Possibility of joining thin-walled components that cannot be welded
- No deformation of heat-sensitive structures
Economic advantages:
- Lower energy consumption – no high-temperature processes
- No skilled welders required – shorter training period
- Eliminating weld seam finishing saves time and money
- Automation and inline integration easier to implement
- Lower investment costs for equipment
Typical industries and applications:
The automotive industry uses structural adhesives for car body components, thereby reducing weight while increasing rigidity. In mechanical engineering, housings, covers, and panels are bonded. The electronics industry relies on bonding for EMC shielding and heat sink connections.
Adhesives are the preferred choice for mixed joints (steel-aluminum), thin sheets under 1 mm, painted surfaces, and when subsequent disassembly is not an issue.
The 5 best types of adhesive for bonding metal
Epoxy resin adhesives (2K): The strength champions
Two-component epoxies provide the highest strength of all structural adhesives and are suitable for heavy-duty metal joints.
Typical products:
- Permabond ET5428: 2K epoxy with 35-40 MPa shear strength on steel
- 3M Scotch-Weld DP490: Tough, elastic variant for vibration loads
Technical characteristics:
- 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
- Pot life: 5-90 minutes
- Curing: 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 dosing systems for reproducible quality.
Ideal applications:
Structural bonding in mechanical engineering, fastening threaded rods and bolts, repairing 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
Structural acrylic adhesives based on MMA 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 characteristics:
- Shear strength: 20-28 MPa
- Temperature resistance: -40°C to +120°C
- Gap bridging: 0.1-6 mm (excellent)
- Pot life: 3-8 minutes
- Handling strength: 10-20 minutes
Ideal applications:
Joining hollow profiles, dirty 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 loaded connections.
Typical products:
- Teroson PU 9225: 1K moisture-curing adhesive for car body construction
- Sika Power 4720: 2K-PU with 18-22 MPa shear strength
Technical characteristics:
- Shear strength: 12–22 MPa
- Elongation at break: 200-600% (highly elastic)
- Temperature resistance: -40°C to +100°C
Ideal applications:
Vehicle bodies (crash resistance), vibration-stressed connections, sandwich elements with different expansion coefficients.
Cyanoacrylate: In seconds for small areas
Cyanoacrylate adhesives cure in seconds and are suitable for small bonding and fixing applications.
Typical products:
- Permabond 910: Universal CA for metals, 15-20 MPa
- Permabond 940: Toughness modified for impact-loaded joints
- Loctite 401: All-purpose CA for quick fixes
Technical characteristics:
- 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 low)
- Fixing time: 5-60 seconds
Anaerobic adhesives: Specialists for threads and joints
Anaerobic adhesives cure in metal gaps when exposed to air – perfect for securing screws and cylindrical connections.
Typical products:
- Loctite 243: Medium-strength threadlocker, removable
- Loctite 270: High-strength threadlocker
- Loctite 648: Bonding agent for shaft-hub connections
Technical characteristics:
- Shear strength: 15-28 MPa (depending on type and gap)
- Temperature resistance: -55°C to +150°C
- Gap range: 0.05–0.5 mm (optimum 0.1–0.15 mm)
Comparison table: An overview of the 5 types of adhesive
| property | Epoxy (2K) | MMA (2K) | polyurethane | cyanoacrylate | anaerobic |
|---|---|---|---|---|---|
| shear strength | 25–40 MPa | 20–28 MPa | 12-22 MPa | 15–25 MPa | 15–28 MPa |
| Maximum temperature | 300-370°F | 120°C | 100°C | 162–248°F | 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 hours | 10-20 min | 30-60 min | 5-60 seconds | 10-30 min |
| flexibility | Low (brittle) | means | High (elastic) | Low (brittle) | Low |
| components | 2K | 2K | 1K/2K | 1K | 1K |
| Best application | Highest strength | Fast + gap filling | flexibility | speed | Threads/shafts |
Selection guide:
- Maximum strength required → Epoxy
- Large/uneven gap → MMA
- Vibration/Crash → Polyurethane
- Fastest fixation → Cyanoacrylate
- Threaded/cylindrical fits → Anaerobic
Surface preparation: The key to lasting adhesion
The strength of an adhesive bond depends 70% on surface preparation.
Step 1: Cleaning
Remove all contaminants: Remove grease with isopropanol or acetone. Wipe in one direction with lint-free cloths. Remove rust mechanically with a wire brush or sandblasting.
Step 2: Mechanical activation
Roughening the surface increases the active area: sanding with 80-120 grit, sandblasting with corundum 60-120 mesh. Ideally, roughness Ra 3-10 μm.
Step 3: Primer (if needed)
Primers improve adhesion on difficult surfaces such as stainless steel, aluminum, or coated metals. Typical primers: Permabond POP, Loctite 7649/7471, Sika Aktivator.
Frequently asked questions (FAQ)
Conclusion: The right choice for every metal connection
Modern high-performance adhesives offer a technically and economically superior alternative to welding for virtually any metal joint.
Choose epoxy resin adhesives if you require maximum strength (up to 40 MPa) and temperature resistance up to 150°C.
Rely on methyl methacrylate for uneven gap widths and fast cycle times.
Use polyurethane systems for structures subject to vibration and crash applications.
Use cyanoacrylate for quick fixes and small bonding jobs.
Use anaerobic adhesives for threads, shaft-hub connections, and tight metal gaps.
The success of any bonding process depends 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
Write here …
