How to Choose a Structural Adhesive

How to Choose an Adhesive Formulation

How is Structural Adhesive Performance Measured?

• Shear Strength—The force an adhesive can withstand when stresses are applied parallel to the bond line. Shear strength is based on bonding metal. Adhesives tend to resist shear stresses better than peel stresses.

  

• Peel Strength—The force an adhesive can withstand when one substrate is pulled away from the bond line. When possible, design joints to minimize peel stresses.

  

• Elongation—Flexibility is important when bonding materials that expand and contract at different rates or when vibration damping is needed. Elongation, one indicator of flexibility, is the maximum an adhesive can stretch before breaking. For example, an adhesive with 50% elongation can stretch to 1.5 times its original length, so a 1" bond line could stretch to 1 1⁄2".

  

• Viscosity—Indicates how thick, or resistant to flow, an adhesive is in its uncured state. Common products are shown below to demonstrate how different viscosities flow on a flat surface.

  

How to Ensure a Strong Adhesive Bond

Surface preparation can be as important as selecting the right adhesive. Requirements vary by adhesive and material, but by following these steps you'll achieve a stronger, more durable bond.

• 1. Clean—Remove debris, corrosion, and tarnish from the surfaces using a cleaner or wire brush. In some cases, stripping paints and coatings is also recommended.

• 2. Abrade—Using sandpaper or steel wool, abrade the surfaces being mated. Adhesives bond best to roughened surfaces.

• 3. Degrease—Remove all remaining dirt, oil, and grit with a degreaser and allow to dry completely

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