By Catherine Veilleux on July 16, 2024
Batteries & EVs
All over the world, automakers and OEMs are using structural adhesives to produce the next generation of cars. For those new to this subject, structural adhesives can seem complex to implement.
In this article, you will find an introduction to adhesives, providing you with a definition, advantages, disadvantages, and tips to obtain good results.
Table of Contents
- What are Structural Adhesives?
- How Do Structural Adhesives Work?
- What are the Benefits of Structural Adhesives?
- What are the Disadvantages of Structural Adhesives?
- How to Improve the Strength of Structural Adhesives?
What are Structural Adhesives?
Structural adhesives are liquids, pastes, double-sided tapes, or films that are designed to join automotive components together. Parts joined by structural adhesives help strengthen the vehicle’s structure. Adhesives are widely used to create structural joints for body-in-white components, chassis assemblies, EV batteries, and glass assemblies.
Thanks to structural adhesives, many EV batteries now play a more important role in improving the vehicle’s load-bearing structure. For this reason, the term structural batteries is seen everywhere in the EV industry.
How Do Structural Adhesives Work?
Structural adhesives rely on joining forces like mechanical interlocking and chemical bonding to create strong bonds between surfaces.
- They are said to mechanically interlock because the adhesive and the part become physically entangled. To maximize the potential for interlocking, it is ideal to roughen or texture the surface beforehand.
- They are also said to create chemical bonds because the surface molecules of the adhesive and the part attract one another like magnets. More chemical bonds can be created if the surface is cleaned prior to applying the adhesive, resulting in a stronger joint.
What are the Benefits of Structural Adhesives?
Automakers use structural adhesives to replace welds and mechanical fasteners like nuts, bolts and screws. Adhesives offer a range of benefits compared to these more traditional joining methods.
- They can bond dissimilar materials that would be difficult to weld. This includes materials with different coefficients of thermal expansion and contraction.
- They are much lighter and help reduce the weight of assemblies. The resulting lower weight helps improve the vehicle’s range.
- Adhesives joints distribute mechanical stress more evenly across bonded surfaces. This creates stronger bonds that reduce the risk of failure.
- They offer more design flexibility due to the reduced mechanical constraints and ability to adapt to complex surfaces.
- Some adhesives are designed to be more flexible (at the cost of some strength) and can therefore better withstand movements and vibrations.
- They can help regulate temperature by providing thermal conductivity/insulation.
- They can contribute to electrical safety and electrical circuits by acting as electrical conductors/insulators.
What are the Disadvantages of Structural Adhesives?
If you are used to other methods, adding structural adhesives to your manufacturing process can seem risky or complicated. But the truth is, many others have already done it and the process is well understood.
With that said, here are the disadvantages that you need to take into consideration:
- Adhesives need time to cure to form an adhesive bond with the substrate. While this can slow down your production process, different types of adhesives can benefit from advanced methods to speed up the curing process (e.g., UV curing, heat curing, two-part epoxy adhesives, etc.)
- Adhesive operations require lots of room on the production floor. Because of that, adding them late in a program can prove difficult.
- Most adhesives require surface preparation to guarantee high-quality and consistent bonds.
- Resistance often comes from engineers and assembly workers who are used to traditional methods. The key to get them on board is to educate them and train them on the benefits and proper use of structural adhesives.
How to Improve the Strength of Structural Adhesives?
Adhesives come with specifications (e.g., shear strength) that were obtained in the controlled environment of a research laboratory. However, achieving the same results can be challenging in the reality of a production floor where multiple factors can lead to inconsistencies.
We recommend laser surface preparation to maximize the bond strength and ensure consistent results. As you can see below, our technical studies show that lasers provide better shear strength and pull-off strength than other surface preparation methods.
Achieving Superior Bonds with Laser Technology
Structural bonding adhesives are already changing the way cars are assembled, making them lighter, stronger, and more efficient at managing heat (especially in the case of electric vehicle batteries). If you are using adhesives and sealants in your manufacturing process, we can develop a laser process to achieve strong bonds, short cycle times, and repeatable results.
Header image source: Gardner Business Media
