Adhesive Bonding

Adhesive bonding joins parts using a cured polymer layer, distributing loads over large areas and enabling mixed-material assemblies with minimal heat distortion.

Overview

Adhesive bonding (structural bonding) joins components by applying an adhesive to prepared surfaces and curing it to form a load-carrying bond line. It works well on thin sections and dissimilar materials because it avoids weld heat input, preserves coatings, and spreads stress over a larger area than most mechanical fasteners or weld beads.

Choose adhesive bonding when you need clean exterior surfaces, vibration damping, electrical isolation, or joining materials that are difficult to weld (polymers, composites, coated metals). Tradeoffs: strength is highly dependent on surface prep, bond-line control, and process discipline; cure time can drive takt time; and joints must be designed for shear/compression rather than peel/cleavage. Adhesives also have temperature/chemical limits and often require validation (lap-shear, peel, environmental aging) for safety-critical use.

Common Materials

  • Aluminum 6061
  • Stainless steel 304
  • Mild steel
  • Carbon fiber composite
  • ABS
  • Glass

Tolerances

±0.005"

Applications

  • Automotive body panel bonding
  • Composite-to-metal brackets
  • Electronics enclosure sealing and bonding
  • Appliance sheet-metal assemblies
  • Sporting goods composite assemblies
  • Architectural metal panel bonding

When to Choose Adhesive Bonding

Adhesive bonding fits low-to-medium volumes when you can control surface prep and cure conditions and the joint can be designed with adequate overlap area. It’s a strong choice for thin parts, cosmetic surfaces, and mixed-material stacks where distortion, burn-through, or galvanic concerns matter. Plan for fixture time and cure time as part of the process.

vs MIG (GMAW)

Choose adhesive bonding when heat distortion, burn-through, or cosmetic weld cleanup is a problem, especially on thin sheet or coated parts. Bonding also helps when you need to join dissimilar materials or isolate galvanic couples. Expect longer process time due to prep and cure, and design the joint to avoid peel loads.

vs TIG (GTAW)

Choose adhesive bonding when TIG’s heat input would warp thin sections or degrade temper, and when you need a smooth exterior with no weld bead or discoloration. Bonding can join metal to composites/plastics where TIG is not applicable. TIG remains better for high-temperature service and small, highly localized joints.

vs Stick (SMAW)

Choose adhesive bonding for assemblies that can’t tolerate weld spatter, high heat, or post-weld finishing, and when shop power/access makes controlled welding difficult. Bonding is better for thin sheet and mixed-material interfaces. Stick welding is better for heavy sections, outdoor field repair, and high-temperature duty.

vs Resistance Welding

Choose adhesive bonding when you can’t access both sides for electrodes, when parts are too thick/insulated/coated for consistent nuggets, or when you want continuous sealing along the joint. Bonding also reduces point-load stress concentrations. Resistance welding is typically faster for high-volume metal-to-metal sheet joints when access is good.

vs Brazing & Soldering

Choose adhesive bonding when you need low-temperature joining without heating the entire assembly, or when joining non-metallics (composites, plastics) alongside metals. Bonding can provide sealing and damping in the same operation. Brazing/soldering is better when you need a metallurgical joint with good high-temperature performance and electrical/thermal conductivity through the joint.

Design Considerations

  • Design for shear: use generous overlap length/area and minimize peel or cleavage loads
  • Specify surface prep requirements (cleaning, abrasion, primer) and call out any coatings that must be removed in the bond zone
  • Control bond-line thickness with spacers/glass beads or joint features; avoid squeeze-out-to-zero thickness
  • Provide fixturing datums and clamp access; include cure time/temperature constraints in the drawing or process notes
  • Add fillets/chamfers or spew grooves to manage adhesive squeeze-out and reduce edge peel stresses
  • Define service environment (temperature, fluids, UV, humidity) so the shop can select and validate the adhesive system