Adhesive Bonding

Adhesive bonding joins metals, plastics, and composites with a continuous bond line, spreading loads, sealing joints, and avoiding heat distortion or weld-induced stresses.

Overview

Adhesive bonding (structural bonding) joins parts using engineered adhesives that cure to form a continuous load-bearing bond line. It works well across dissimilar materials—metals, plastics, and composites—while also sealing against fluids and isolating galvanic corrosion. The process avoids high heat, so it preserves base material properties and minimizes distortion on thin sections and precision components.

Choose adhesive bonding for thin sheet assemblies, composite-to-metal joints, and large surface-area connections where welds, fasteners, or holes would weaken the part. It excels in shear and compression but is weaker in peel and impact unless you design the joint correctly and select the right adhesive. You must control surface preparation, bond line thickness, and cure conditions, which adds process time and requires fixturing. Long-term performance depends on adhesive chemistry and environment, so validate for temperature, humidity, and chemical exposure before committing to production.

Common Materials

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

Tolerances

±0.010" on bond line gap and joint position, assuming accurately machined or molded mating parts

Applications

  • Automotive body and closure panels
  • Aircraft composite-to-metal joints
  • Electronics housings and covers
  • Structural glazing and façade panels
  • Appliance and HVAC enclosures
  • Sporting goods composite assemblies

When to Choose Adhesive Bonding

Use adhesive bonding when you need to join thin or dissimilar materials with minimal heat input and a continuous load-spreading joint. It suits medium to high production where joint prep, fixturing, and cure time can be standardized. Prioritize it when sealing, corrosion isolation, and clean external appearance matter as much as strength.

vs MIG (GMAW)

Choose adhesive bonding instead of MIG welding when you must join thin sheets, dissimilar metals, or metals to composites without burn-through, distortion, or visible weld beads. It also makes sense when you need combined structural strength and sealing in one operation, such as automotive body panels and closures.

vs TIG (GTAW)

Choose adhesive bonding over TIG when aesthetics, minimal rework, and low heat input outweigh the need for fully fusion-welded joints. It’s especially useful for large, thin, or cosmetic panels where TIG distortion or discoloration would be unacceptable, and for joints that must bridge metals and non-metals.

vs Stick (SMAW)

Choose adhesive bonding instead of Stick welding for thinner gauges, precision assemblies, or mixed-material joints where Stick is too aggressive or imprecise. It fits better in production environments with repeatable fixtures, controlled cleanliness, and where spatter, slag, and heavy weld beads would cause downstream issues.

vs Brazing & Soldering

Choose adhesive bonding over brazing and soldering when you want to avoid high temperatures, flux residues, and metallurgical changes, particularly with heat-sensitive alloys or composites. It also works better when you need a wide bond area with integrated sealing rather than a fillet joint concentrated at an edge.

vs Resistance Welding

Choose adhesive bonding over resistance welding for coated, multi-layer, or dissimilar stacks where consistent nugget formation is difficult or electrode access is limited. It suits large, continuous seams and mixed-material joints where you want structural strength without localized heat-affected zones or electrode marking.

Design Considerations

  • Design joints to load the adhesive mainly in shear or compression; avoid peel and cleavage by using laps, steps, or flanges
  • Provide adequate bond area and consistent overlap length; short, narrow joints drive up stress and reduce durability
  • Control bond line thickness with shims, spacers, or adhesive beads; most structural adhesives perform best within a narrow gap range
  • Specify clear surface preparation requirements (cleaning, abrasion, priming) and ensure they are realistic for production
  • Add simple mechanical features—tabs, tongues, or light fasteners—to aid fixturing, maintain alignment, and provide fail-safe backup
  • Document environment and life requirements (temperature, fluids, UV, fatigue) so the shop can select an appropriate adhesive system and cure schedule