Adhesive Education Series: Understanding Adhesive Joint Design
In recent posts, we’ve looked at the benefits of adhesives over traditional mechanical fasteners when assembling materials. Now, let’s take a closer look at adhesive joint designs used during assembly.
What is an Adhesive Joint Design?
Adhesive joint design is way in which two materials are bonded/assembled together to accommodate applied stress. Using an adhesive joint design works well when joining metallic or non-metallic dissimilar materials together.
Benefits of an Adhesive Joint Design
Adhesive joint designs offer the following benefits in the assembly process:
- Reduced stress concentration, which results in stiffer joints and structures
- Improved sealing, meaning that a continuous adhesive bond can also offer corrosion protection
- Improved aesthetics, given the removal of spot welds and fasteners
Types of Adhesive Joint Designs
There are several types of adhesive joint designs depending on the needed application. Common joint designs include:
- Butt joints: Butt joints bond two components end to end. They are not recommended for heavy load bearing forces but can be used for significant torsal loading.
- Silyl-modified polymer (SMP) sealants are good for butt joints, due to their flexibility.
- Scarf joints: These are similar to butt joints. However, they offer increased shear resistance due to having joints leveled at matching angles. Scarf joints are not recommended for use with thin sheet adherends, though.
- SMP and hot melt polyurethane adhesives are good for these types of joint designs.
- Lap joints: These adhesive joints cover more surface area than butt and scarf joints. However, they can be susceptible to peeling.
- SMP, hot melt polyurethane and polyamide adhesives are good for lap joints.
For a visual, please refer to the diagram below:
For more information on adhesive joint designs and adhesives best suited for them, contact a Bostik expert.