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Bonding and welding are two crucial processes for the effective joining of composite structures without the need for fasteners, though they are not interchangeable. Bonding requires an adhesive or bonding agent to “attach” parts and structures made of similar or dissimilar materials together, creating a strong, structural connection. Alternately, welding joins two composite parts together through the use of heat and/or force, resulting in the “disappearance of joint surfaces … and creating a unitized structure.”

What are their advantages? Both methods are ideal for achieving complex shapes and customized joint designs that may not be possible with traditional mechanical fasteners. Adhesive bonding, a popular method for automotive applications, enhances structural integrity, as adhesive joints can distribute stresses evenly across the bonded interface. Welding, which is playing an increasing role in thermoplastics joining for aerospace, is considered a strong assembly option for its ability to remove the identifiable interface between joined materials, creating a strong joint.

CW has developed and published a variety of content that digs deeper into each process:

BONDING

• Determining steel/composite failure load of bonded repair assemblies
• AnalySwift receives NASA STTR contract to enable second-use spacecraft infrastructure
• TFP glass veils prove integral for fiber-metal laminate applications
• Aerospace project secures funds for developing lightweighting technology
• XlynX Materials BondLynx and PlastiLynx for low surface energy PP, PE substrates

WELDING

• Assembling the Multifunctional Fuselage Demonstrator: The final welds
• Novel insert technology enables arc stud welding with composites
• Hexcel, Arkema present CFRTP aerospace demonstrator in HAICoPAS
• Fraunhofer IWS completes MFFD longitudinal fuselage joint using CONTIjoin technology
• Welding is not bonding
• Aitiip Technology Center reports dismantling of thermoplastic parts using resistance welding

• Welding thermoplastic composites

Want to learn more? CW’s April 2025 Tech Days webinar is focused on composite bonding and welding, providing additional insights into challenges and strategies for each. Don’t miss out. Learn more here.