How To Select The Right Structural Adhesives

In many industries, adhesives play a crucial role in bonding materials together. Structural adhesives are particularly well-suited for assembling and joining components that require exceptional strength and durability. Structural adhesives are an important element in the structural integrity of load-bearing and stressed assemblies during their forecast service lives. They are also often used to replace traditional fastening methods — such as welding or riveting — as they improve aesthetics and reduce weight. Epoxy adhesives can bond a wide range of materials.

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Given the diverse range of formulations in the market, selecting the appropriate adhesive for a specific application can be challenging. This article will cover the key factors to consider when choosing the right type for your needs.

Key Considerations When Selecting the Best Structural Adhesives for Your Project

A systematic approach to identifying your requirements is crucial for finding the appropriate structural adhesive. The following are several factors you should consider:

Bonding Process

Defining your precise needs for bonding agents requires careful consideration of the type of bonding process required. For instance, depending on the specific requirements of your application, you may need to use multiple bonding processes and structures. Adhesive application methods include manual application, spray application, and automated dispensing.

Manual application entails using a brush, roller, or syringe to apply adhesive by hand. Spray application involves using a spray gun or similar device to spray the product onto the substrate. Finally, automated dispensing employs a machine or robot to apply the product with precision and consistency, ensuring a reliable and repeatable bond. The application method can affect the adhesive’s performance and effectiveness under the particular design requirements.

Bond Strength

Bond strength measures the adhesive’s ability to hold two or more surfaces being bonded together under mechanical stress or load. A strong and long-lasting bond typically requires epoxy adhesives due to their high strength and durability. This makes epoxy resins suitable for bonding materials subject to high loads or stresses. Structural adhesives can improve product performance by distributing loads more evenly, thus better addressing stress concentrations and fatigue resistance.

Material Compatibility

Modern structural adhesives offer a vast array of options. Using purpose-made adhesives specifically designed for bonding particular materials is strongly recommended. This is because different products have varying chemical compositions and bonding mechanisms that work best with specific materials. The adhesive must be compatible with the particular substrate.

For example, some adhesives may be more suitable for bonding metals, while others may work better with plastics. Additionally, adhesives designed for composites often have specific formulations optimized for the unique challenges of bonding these materials. These challenges may include their low surface energy and sensitivity to moisture. Overall, structural adhesives can offer design flexibility since they can bond together a wide range of materials, but some adhesives are better suited for particular joint designs.

Curing Time

The curing time is the amount of time it takes for the adhesive to fully harden and develop its maximum strength. It can vary widely depending on the adhesive type, the bonded materials, and the environmental conditions. Selecting an adhesive that cures quickly can save time and increase efficiency, while a longer curing time can offer a stronger and more durable bond. A longer curing time allows for adjustments to be made before the adhesive sets or cures. The curing time needs to be appropriate for the production time requirements and the particular application’s requirements.

Temperature Resistance

Structural adhesives can maintain their bond strength only within certain temperature ranges that vary between different types of adhesives. Therefore, comparing the temperature parameters of various adhesives is crucial. This will ensure you select a product that can withstand your application’s heating or cooling conditions or cycles.

A Better Finished Appearance and Resistance to Many Harsh Environmental Conditions

Structural adhesives can offer improved aesthetics, as they can bond materials with no visible fasteners. They produce a better finished appearance to an application. Since epoxy resins can fill gaps between materials, they are often used in applications where a perfect fit is not possible. Epoxy resins also are resistant to a wide range of chemicals, making them suitable for harsh environments. Epoxy resins can eliminate potential corrosion issues at the bond line, and can withstand many environmental conditions that the bonded materials will experience in their life cycle.


An adhesive should be chosen without compromising quality, as a cheaper product may eventually cost more if it fails to perform. It is worth considering the long-term benefits of investing in a high-quality adhesive, such as increased durability and enhanced bond strength. This can lead to cost savings on future maintenance and repairs. Reduced maintenance, improved durability and increased performance make epoxy resin a cost-effective solution to your adhesive needs. The cost of a high-quality adhesive should always be considered in relation to the total cost of the finished product or application.

Choose United Resin for Exceptional Adhesive Solutions

For over 50 years, United Resin has been delivering high-quality epoxy resin systems offering adhesive solutions for various industries. United Resin has a variety of specialty and structural adhesive systems that meet the requirements of the aerospace, marine, automotive, construction and many other industries. Our portfolio of structural adhesive systems includes:

Metal Paste with 215 Hardener, a thixotropic structural adhesive which cures at room temperature and possesses superior strength up to 350F/177C. It is ideal for filling gaps and bonding materials as this system develops adhesive strength quickly.

High-Temp Adhesive with 210 Hardener, a two-component, low viscosity, room temperature cure system with excellent strength at 300F/149C. It may be used for repair applications, including laminating, injection, and coating.

Flex A Bond with 740, available in our regular formulation, a sprayable formulation and a paste formulation. A key advantage of this epoxy structural adhesive is its ability to bond hard to bond materials such as PTFE, nylon, ceramics and stainless steel. This system also works well as a vibration dampening adhesive material. As with all epoxies the Flex A Bond with 740 has very good chemical resistance.

Hi-Strength Tuff Bond with 250 Hardener, a non-sagging thixotropic room temperature cure, high strength adhesive for a variety of substrates, including those hard to bond materials such as PTFE, nylon, acetal, and stainless steel. Hi-Strength Tuff Bond with 250 Hardener is a toughened industrial grade adhesive that has superior thermal shock resistance, chemical resistance, vibration dampening and impact resistance.

Our manufacturing processes are designed for consistent quality and performance. We also have global shipping capabilities, ensuring we can reach you regardless of location.

Contact us today to explore our high-quality epoxy resin systems, including structural adhesive solutions. You can also request a quote to see how we can help meet your needs.