Designers find new ways to use adhesives that bond on demand.
What is in this article?:
- Where adhesives beat mechanical fasteners
- A retrospective on conventional joints
A retrospective on conventional joints
Structural adhesives have taken over thousands of bonding applications once dominated by metal-joining processes such as welding, riveting, staking, and bolting. Here are some reasons why:
- Preload is critical in riveted or bolted joints because the joint draws its strength from the "traction" between the surfaces. Adhesives need no preload.
- Tensile loads concentrate on the fasteners or spots where joined surfaces are welded. In an adhesive joint, the entire surface of the joint carries the load.
- Dynamic joints tend to loosen or fail in fatigue. Adhesive joints have no known fatigue limit.
- High-strength fasteners are subject to hydrogen embrittlement, a phenomenon that does not apply to adhesive joints.
- Mechanical fasteners and welding demand mating surfaces conform to within a few thousandths of an inch of each other to be effective. Most adhesives, on the other hand, fill irregularities and gaps.