VERSATILITY

Ultrasonic welding is a well-established joining method for thermoplastic (TP) materials, particularly in automotive parts manufacturing and consumer products packaging.

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The science of continuous ultrasonic welding (CUW) is based on the end effector’s tip or sonotrode making physical contact with the composite material being welded. This physical contact occurs as the sonotrode travels along the weld path. In high-performance polymer composite applications, the system is typically running at 20 Khz making contact 20,000 times per second. The impact of the sonotrode's energy forces the resin molecules (polymer chains) in the TP matrix to bump into each other. This causes viscoelastic or through-thickness heating that can occur almost instantaneously.  By precisely controlling parameters such as amplitude, force and speed, viscoelastic heat can be generated to bring the resin material above its Tg (glass transition temperature) where the polymer (resin) changes from a hard glassy state to a soft rubbery state or vice versa. Above Tg, the polymer chains are mobile. When the part cools, the resin returns to the glassy state and the polymers become locked forming a weld.  Adjusting parameters allows for varying degrees of welding, tacking, compacting or debulking.

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Traditional automotive industry applications use high forces to plunge weld thin parts made from neat resin (no fill) or relatively low fiber-content materials.  Typically, this approach requires use of geometric features known as energy directors that are molded or milled into the surface of the weld interface.  Resin-rich film inserts can also be placed at the weld interface to help initiate melt and flow at the bond line.

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However, energy directors and film inserts can be difficult to implement in high-performance (low resin/high carbon fiber volume) composites designed for use in advanced structures.  In commercial aerospace, design limitations or certification requirements can prohibit the inclusion of dissimilar materials or geometric discontinuities at the joint.  Beyond aerospace, circular manufacturing initiatives are having an impact in automotive, industrial and consumer segments. TP use cases are growing based on the sustainability and performance characteristics of including reduced tooling, ambient low power processing, durability, corrosion resistance, field repair, repurposing and recyclability.   

 

​Agile’s breakthrough developments in ultrasonic joining can be uniquely enabling regardless of resin matrix or fiber volume.  Thus, its technology applies to high-performance aerospace, mid-market automotive or commodity consumer applications with carbon fiber, fiberglass or nylon fill as used across diverse industries and applications.  The CompositesWorld TP performance pyramid below illustrates the breadth of resin matrices applicable to Agile’s approach.

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