Are you looking for a dependable adhesive solution for bonding metal materials? If so, you’ve come to the right place. While there are plenty of adhesive options on the market today, it can be difficult to know which one best fits your project needs.
To help narrow things down and make an informed decision, we’ve compiled this guide that reviews some of the strongest epoxy products available specifically designed for metal-bonding applications.
Table of Contents
Introduction to the strongest epoxy for metal bonding
Epoxy adhesives are one to two-part systems that create bonds with superior strength and durability. They’re used in metal bonding applications due to their high heat resistance, excellent chemical resistance, and superior electrical insulation properties.
At the same time, epoxy products come in a variety of different formulations that range from fast-setting to slow-curing, making them a versatile choice for metal bonding. However, not all epoxy adhesives are created equal and some have different properties that make them better suited for specific applications.
To help you make the best decision when selecting your adhesive solution, let’s take a look at some of the strongest epoxy products available for metal bonding.
Comparing the strongest epoxy for metal bonding
Evaluating the best metal bonding adhesives
This process starts with looking at the different types of epoxy available. There are two major categories of metal bonding epoxy: one-part and two-part systems.
One-part epoxy
One part epoxy, also known as heat activated epoxy or heat curing epoxy, is the strongest glue for metal-to-metal bonding. It typically has a bond strength of 6000 psi (41 N/mm2) on steel, which is higher than that of two-part epoxy and structural acrylic adhesives. One part epoxy not only offers the highest bond strength but also provides superior heat resistance to other epoxy types; standard one part epoxies can withstand temperatures up to 350°F (180°C), while high heat resistant varieties can handle up to 570°F (300°C).
In terms of chemical resistance, one part epoxy performs excellently against both non-polar solvents (such as motor oil, toluene, and gasoline) and polar solvents (including water, ethylene glycol, isopropyl alcohol, and acetone).
Advantages and downsides of one-part epoxies
Advantages of one part epoxy adhesives include:
- Rubber toughening for high-peel strength and impact resistance
- No mixing required
- Excellent environmental durability
- Rapid cure, increasing production rates
- Solvent-free, improving workplace safety
- Cost savings over brazing and welding
- Low odor, enhancing workplace environment
However, there are some downsides to using one part epoxy:
- Other adhesive types perform better on plastics and other substrates
- Cure process for one part epoxy can be too high for many plastics
- Opaque appearance may not be suitable for applications requiring transparency
- Viscosity of one part epoxy adhesives is relatively high
- Shore hardness of D80 to D85, which may not be suitable for applications requiring flexibility
Two-part epoxy
Two-part epoxy is a versatile and strong adhesive commonly used for bonding various materials, including metal, plastic, wood, and ceramics. As the name suggests, it consists of two components: a resin and a hardener. When these components are mixed together in the correct proportions, a chemical reaction occurs, which causes the epoxy to cure and harden, forming a durable bond.
The typical bond strength of a two-part epoxy on steel is around 3000 psi (20 N/mm2), which is lower than that of one-part epoxy but still considered very strong. Two-part epoxies usually have good heat resistance, with standard varieties able to withstand temperatures up to 175°F (80°C) and high heat resistant versions up to 570°F (300°C).\
Advantages and downsides of two-part epoxies
Some advantages of using two-part epoxy adhesives include:
- Excellent adhesion: Two-part epoxies bond well to a wide range of materials, including metals, plastics, wood, and ceramics.
- Gap filling: They can fill gaps and bond irregular surfaces, making them suitable for various applications.
- Chemical resistance: Two-part epoxies generally have very good resistance to both polar and non-polar solvents.
- Adjustable cure times: The curing time can be adjusted by selecting different hardeners or by varying the mixing ratio, allowing for a controlled working time.
- Range of formulations: Two-part epoxies are available in various formulations, providing flexibility in terms of viscosity, working time, and final properties.
However, there are some limitations to two-part epoxy adhesives:
- Mixing: The two components must be mixed accurately in the specified proportions to ensure proper curing and final bond strength.
- Pot life: After mixing, the epoxy has a limited working time (pot life), during which it must be applied to the surfaces to be bonded.
- Cure time: Two-part epoxies generally require longer cure times compared to one-part epoxies, which can affect production rates.
Despite these limitations, two-part epoxy adhesives are widely used in various industries due to their excellent bonding capabilities, strength, and versatility.
Top non-epoxy adhesives for metal-to-metal bonding
Methacrylate adhesives, also known as methyl methacrylate (MMA) adhesives, are a type of two-part adhesive known for their strong metal-to-metal bonding capabilities. They consist of a resin and an activator, which need to be mixed in the correct proportions to ensure proper curing and bonding.
Methacrylate adhesives have several advantages, including:
- Excellent adhesion: They bond well to various metals, such as aluminum, stainless steel, and titanium, and other materials like plastics and composites.
- Versatility: They can bond dissimilar metals together, making them suitable for a wide range of applications.
- Temperature, chemical, and environmental resistance: Methacrylate adhesives can withstand high temperatures and resist various chemicals, including fuels, oils, and solvents. They also offer excellent resistance to moisture, UV radiation, and weathering.
- Fast cure time: These adhesives can cure quickly, often in just five minutes, and achieve full strength within a few hours, making them ideal for production environments where efficiency is important.
Methacrylate adhesives are indeed a strong, versatile, and durable adhesive choice, particularly for metal-to-metal bonding, and are widely used in various industries due to their excellent performance characteristics.
How to choose the right glue for metal
When selecting an adhesive for metal-to-metal bonding, there are a few key factors to consider:
Type of metals
Different adhesives may be better suited to different types of metals. For example, methacrylate adhesives are particularly suitable for aluminum and stainless steel but not as effective on titanium.
Environment
Consider the environment in which the adhesive will be used and how it may affect its performance. For example, if the parts will be exposed to extreme temperatures or harsh chemicals, an epoxy with good heat and chemical resistance should be chosen.
Cure time
The cure time is important for production processes as a faster curing adhesive can significantly reduce production time.
Strength
The strength of the bond is also critical, as some adhesives may be more suitable for certain types of applications than others. For example, methacrylate adhesives are well-suited for permanent bonds that require high strength and durability.
Ultimately, when selecting an adhesive for metal-to-metal bonding, it is important to consider the type of metal, environment, cure time, and strength requirements. By doing this, you can that the right adhesive is chosen for your application.
Final thoughts on the strongest epoxy for metal
While two-part epoxy adhesives are widely used for metal-to-metal bonding, other non-epoxy adhesives such as methacrylate can also be effective. It is important to consider the type of metals, environment, cure time, and strength requirements when selecting the right adhesive for your application. Ultimately, by selecting the right adhesive for your application, you can ensure a strong, durable bond between two metal surfaces.