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Vaporizing Foil Actuator Welding (VFAW)

Vaporizing foil actuator welding (VFAW) is a novel manufacturing process that generates strong metallic bonding between sheet metal structures. Most importantly, VFAW enables creation of welds between high strength steel and aluminum alloy components, allowing for innovative multi-material structures to be produced. Implementation of this new bonding technology provides an effective means of reducing overall weight in vehicle assemblies, as it allows lighter aluminum alloy components to be utilized in place of heavier steel designs.

Welding between similar and dissimilar aluminum alloys is also possible using VFAW, producing joined regions with strength properties that exceed those of the parent material. Overall, VFAW provides a promising advancement for the future of vehicle manufacturing capabilities, enabling lightweight design implementation not possible by other means.

Proposal

The final configuration will be capable of conducting several sequential impact spot welds between large sheet metal structures, demonstrating versatility for use on future automotive joining applications. If you are interested in participating in the VFAW project, please contact John Bockbrader or Nate Ames (emails to the right).

The Process

Through use of an ultrafast capacitor bank system, high intensity current is discharged through a thin aluminum foil structure (pictured below), causing a small portion of it to rapidly heat to the point of vaporization. The energized vapor generates a high pressure impulse behind a flyer workpiece, causing it to accelerate toward a target workpiece at speeds of several hundred meters per second. The impact event initiates jetting of surface impurities away from the impact zone and results in the formation of a strong interface between mating surfaces. Additionally, no heat-affected zone is generated with this technique, allowing for the original mechanical properties of the workpiece materials to be retained. This provides a new and useful means for creation of lightweight and multi-material vehicle structures, featuring high strength steel and aluminum alloys.
 
Vaporizing Foil Actuator Welding
 
 
Vaporizing Foil Actuator Welding - In this technique, electrical energy stored in a capacitor bank is released through a switched circuit that contains a thin metal foil conductor (top picture). The schematic diagram illustrates the cross-section of the welding process.
 

Video: Vaporizing Foil Actuator Welding by Collision of Dissimilar Metals

VFAW Adapted for Fully Automated Robotic Welding

 

In order to advance the manufacturing readiness level of this technology, VFAW is being adapted for use with a fully automated robotic welding system. Similar high-volume production configurations are utilized for resistance spot welding processes, and this advancement of technology implementation will serve as an excellent demonstration of the potential capabilities for VFAW in a high-volume production manufacturing environment.

Challenges for Adaptation to Robotic Configuration

In order to successfully adapt VFAW to this robotic configuration, a number of technical challenges must be addressed through proper design implementation

  • Proper assembly fixturing to existing equipment
  • Implementation of well-insulated high voltage terminal circuitry
  • Durability of the housing assembly structure for repeated use

Additionally, challenges concerning automated loading and unloading of foils used for each test will be addressed with this design, as well as solutions for maintaining clean, undamaged working surfaces for running successive trials.