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Solutions for bonding and gluing Metal
Let's work together! 3M metal bonding products are constantly evolving to better meet your needs. If you need help finding the right adhesive or tape to bond metal or have other questions about 3M metal bonding and gluing solutions:
Bonding metal for professionals
Metal is one of the materials that are relatively well suited for bonding. Nevertheless, it is important to find the right product for the corresponding application. The choice of adhesive, a load analysis as well as potential surface treatment are decisive factors that lead to a good bond. Then bonding can increasingly replace welding, screwing, or riveting. These are advantages that are used today in mechanical engineering, vehicle construction, architecture, or the electrical industry.
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- What kind of metal is it?
- What is the surface like (oxidized, oily, surface-treated, painted)?
- What is the geometric bonding surface (flat, angular, or punctual)?
- Are there any processing specifications or constraints?
- Type and extent of load on a bond (dynamic, heavy-duty, heat-resistant)?
- Where will the bonded metal be used later?
Already here it becomes clear: There is no such thing as one adhesive for metals. The properties of the adhesive, such as composition, viscosity or temperature resistance must be matched to the surface to be bonded. For example, precisely fitting parts where small surfaces are joined together place different demands on the adhesive than in the case of surface laminations.
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Joining with Mechanical Fasteners vs. Adhesive Bonding
Mechanical fasteners have been an integral part of metalworking for many years, and they’re a popular solution for joining metal. While metal fasteners are often the most well-known choice, they might not be the best for your needs. Industrial adhesives provide six key benefits over other industrial assembly methods:
- Eliminate the need to drill holes – Drilling is time-consuming, while holes can weaken the substrate and be more easily affected by corrosion
- Distribute stress evenly across the bond – rather than concentrated stress across several fastener points, the substrate is evenly stressed over the area of the bond
- Use thinner, lightweight materials – even stress distribution means the substrate doesn’t need to be as thick to accommodate fastener stress points
- Bond and isolate dissimilar materials – Industrial adhesives can bond to a range of metal and non-metal substrates as well as reducing the chance of galvanic corrosion
- Bond and seal simultaneously – adhesives form strong bonds while keeping fluids out or in
- Reduce vibration – resilient adhesives can help dissipate energy rather than transmit it
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Welding / Brazing / Soldering (Thermal Bonding) vs. Adhesive Bonding
Thermal bonding applications like welding are popular due to their value for money and quick turnaround time. Like adhesive bonds, thermal bonds are durable and seal when applied properly. However, adhesives offer several benefits which thermal bonding does not:
- Enable the use of dissimilar metals – the adhesive isolates different metals against galvanic corrosion
- Rework the bond – the bond is easier to disassemble, rework and repair
- Reduce labour costs – fast and easy application that contributes to reducing the total cost
- Improve aesthetics – the bonding process does not distort or discolour the substrates
- Enable the use of thinner substrates – because the metal is not distorted a thinner substrate can be just as strong
- Lower energy costs – less energy-intensive than thermal bonding
- Improve worker comfort and safety – most adhesives can be applied at room temperature without the need for intense heat
- Faster finishing – without the risk of oxidisation or deformation finishing is quicker and easier
Choice of adhesive for metal
A wide range of metal adhesives or adhesive tapes is available today for bonding metals to each other or to other composite materials: for high tensile shear strength, as well as for good temperature and chemical resistance or dynamic loads.
Not only when bonding metals does the selection of adhesives or adhesive tapes strongly depend on the energy of the surface to be bonded. The so-called surface energy is a measure of how well an adhesive can adhere to the surface to be bonded. Compared to many plastics, metals have a high surface energy of between 1,000 and 5,000 mN / m (polytetrafluoroethylene, PTFE, for example, only 18 mN / m) and are therefore suitable for good wetting with adhesives.
For the selection of a suitable adhesive, this means choosing an adhesive with low surface tension, because the lower the viscosity of the adhesive, the easier it is to wet the workpiece surface. Most adhesives for metal are therefore two-component adhesives consisting of and hardener. Acrylic, epoxy, and polyurethane adhesives are predominantly used.
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Acrylic adhesives
Acrylic adhesives are robust. For structural bonding of metals with coated, painted surfaces and plastics, reactive, two-component acrylate-based adhesives, such as MMA adhesives, are also suitable. They also adhere to slightly oily surfaces and are therefore well suited for metalworkers. With approx. 20 MPa, they achieve good strength.
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Epoxy adhesives
Epoxy offer the highest strengths (30 to 40 MPa). However, they are very demanding in terms of surface preparation: 100% freedom from grease and dust is a prerequisite. Rust or oxide layers on the metal surface are always a problem. Epoxy's usually adhere very well to rust, but the rust does not adhere well to the surfaces of the parts to be joined. Steel parts must therefore be completely derusted and ideally polished. Aluminum can also be bonded very well with epoxy adhesives, as well as with acrylate adhesives, but these have lower strengths. Epoxy adhesives are again suitable for brass, as copper materials form copper acrylates in combination with acrylate adhesives, which do not last long. As with steel, the surfaces must first be sanded to a bright finish.
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Polyurethane adhesives
Polyurethane adhesives are UV-resistant and also bond painted metal surfaces together. Reactive two-component adhesives based on polyurethane (PUR) with a long working time are suitable for bonding composite panels where larger surfaces of different materials have to be fixed. Single-component PUR adhesives or MS polymers are often used for adhesive joints of up to several millimeters in width for materials that are permanently or temporarily exposed to vibrations.
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Anaerobic adhesives/sealants
Anaerobic adhesives/sealants (also liquid sealants) prevent leakage, vibration, detachment, and corrosion of the joint. They are used to secure and seal threads, to secure cylindrical parts, to seal and to seal pipes. For example, gearbox housings, baseplates on the crankcase, water pumps or camshaft housings on the cylinder head can also be sealed.
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Adhesive tapes
Adhesive tapes for metal bonding, e.g., those with acrylate adhesive, also have high adaptability to the surfaces to be bonded. They are ideal for bonding similar and different materials such as metal (e.g., steel, stainless steel, and aluminum also with powder-coated surfaces) with plastic, wood, or glass. High-performance tapes, such as the 3M™ VHB™ Tape range from 3M, are made of 100% closed-cell acrylic adhesive, and allow for tension-free bonding due to the flexibility of the adhesive bond. They are temperature, weather, and UV resistant.
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Hot-melt adhesives
Hot-melt adhesives are also common: these are applied in a molten state approx. 150°C - 190°C and the parts must be joined before the "melt" solidifies. An example of this is the hot glue gun.
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Sealants
The use of Sealants has been increasing for some years. These are systems that originally come from the field of sealing but are also very efficient in terms of adhesive technology. These adhesive sealants, preferably in single-component use, are also offered based on polyurethane (PUR) or as so-called silane-terminated polymers (STP, MS). Individual 2-component systems and so-called booster systems also hold their own here. This process, often referred to as sealing adhesive or thick-film adhesive, shows its strength in the fact that the adhesive joint retains a certain elasticity and thus compensates for tensions, expansions, or vibrations. This property is often used in vehicle, machine, and ventilation construction. In other words, applications where vibrations and oscillations frequently stress a bonded joint.
Bonding to Different Metals
Metals are easy to bond, but each is unique. These are the major types of metals.
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Stainless SteelStainless steel is an iron alloy with carbon and other metals added for corrosion resistance. Common for household cookware, cutlery, commercial kitchens and food processing, it is also used for surgical instruments, in the automotive and aerospace industries, and for general industrial equipment and building facades. Stainless steel is easy to bond but may need to be cleaned to remove dirt, dust, fingerprints and machine oil.
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SteelSteel is an alloy of iron with a small amount of carbon to increase strength. Steel surfaces are typically coated before or after bonding to prevent corrosion, either with zinc (galvanized steel) or some type of paint. If coated before, the adhesive is actually bonding to any coating rather than the steel itself, which affects surface energy and how well the adhesive wets out. Other adhesives and tapes are designed to survive the coating or painting process.
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AluminiumAluminium is a relatively soft, durable, lightweight, ductile and malleable metal that is easily machined, cast, drawn and extruded. It is nearly always alloyed to improve its mechanical properties. Aluminium resists corrosion because a thin layer of aluminium oxide forms almost immediately when the bare metal is exposed to air. Aluminium often needs to be cleaned or abraded to remove dirt, dust, fingerprints and machine oil.
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Copper-Containing MetalsCopper is a soft, malleable, ductile metal with excellent electrical and thermal conductivity. It is subject to corrosion and should not be in contact with materials that cause or increase corrosion, particularly other metals. Metals that can corrode over long periods of time, such as copper and its alloys brass and bronze, require special consideration when selecting an adhesive. 3M makes specially formulated tapes and adhesives that do not promote corrosion and are copper-compatible.
Surface preparation before bonding to metal
The general rule for metals is: Surface pre-treatment improves wetting with adhesive! Since oxidations as well as oils and greases form separating layers on which adhesives can bond well, but this layer in turn does not adhere sufficiently firmly to the metal, they must be carefully removed. The following applies: First clean or degrease, then grind or blast, otherwise impurities can be ground (blasted) into the metal during the grinding process and continue to have a separating effect on the adhesive. In addition, metals that are stored at cold or lower temperatures should be sufficiently tempered before bonding to avoid condensation.
Metal bonding is regulated in VDI 2229.
Customer Testimonials
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See how 3M Adhesives helped PDG to improve design and durability of wheelchairs
Are you looking for an alternative to welding which can significantly improve production efficiency? See how 3M™ Scotch-Weld™ Epoxy Adhesive helped PDG Mobility design stylish, lighter weight wheelchairs while speeding up assembly time.
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Find out how WS Steel reduced their manufacturing costs by 20%
WS Steel were using spot welding for their medical cabinet production processes. By making the switch to 3M™ VHB™ Tape, they removed the risk of deformation while speeding up their assembly process and cutting back on manufacturing costs. This meant they could manufacture the same high-quality goods while improving aesthetics.
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See how Hansen Signs company cut their labour time by 80% using 3M™ VHB™ Tape
Hansen Signs design and manufacture a range of signages. With 3M™ VHB™ Tape, they increased their production efficiency by using tape for bonding different materials including metals, composites, and plastics - speeding up their assembly processes. Outdoor signage needs to resist extreme weather conditions. 3M™ VHB™ tapes provided strong bonding and sealing that withstands harsh environmental conditions
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Watch how 3M™ VHB™ Tape helped Zanetti create customized products
3M™ VHB™ Tapes have helped Zanetti produce complex, fully customized windows and doors while reducing the amount of materials they need per operation. The tapes are easy to use across a range of substrates and form completely invisible bonds, making it easier for the team to meet custom design specifications.
How can we help?
Let's work together! 3M products are constantly evolving to better meet customer needs. If you need help finding the right product for your project or have other questions about 3M solutions: Call Us 0870 608 0050
