Core Technologies

The Center provides science-based research to Center members in a consortium environment.  This collaboration strengthens and enlarges the research capabilities of both its academic and industrial members through conducting cooperative interdisciplinary research programs between industry and acadamia.  Research topics range from fundamental to applied research related to engineered material systems and advanced manufacturing processes, including additive manufacturing. The synergistic research carried out in the Center ranges from designing to processing next-generation structural materials via disciplined planning and assessments using in-house state-of-the-art research techniques and analytic equipment.

The Technologies

Friction stir (FS) technologies are a family of “green” processing and joining technologies that involve local mechanical stirring of metallic workpieces or sets of metallic workpieces with specially designed interchangeable, non-consumable tool bits referred to here as Stirbits®. The purpose of the FS process includes: 1) to locally modify (refine and consolidate) the microstructure of the metal within a given workpiece, and/or 2) to permanently join a set of workpieces. The basic process is carried out in the solid state and involves forcing a spinning, non-consumable tool into the workpiece(s) and then along a prescribed path, e.g. along the joint line between two or more components to be joined. Because the processed material remains solid (not becoming liquid) throughout the process cycle, FS tools experience frictional wear with use and are, therefore, periodically replaced in production operations to maintain the prescribed tool geometry.

  • Friction Stir Welding (FSW)
  • Friction Stir Processing (FSP)
  • Friction Stir Spot Welding (FSSW)
    • Refill FSSW
    • Basic FSSW
  • Friction Stir (Solidstate) Additive Manufacturing


“Friction stir butt welding” was first introduced by The Welding Institute (TWI) of Cambridge, UK, in 1991 as a permanent butt joining process for metals and a limited number of plastics. [1] The process soon became known as “friction stir welding” (FSW) [2] as the use of the technology was expanded to include lap joints, corner joints, combined butt and lap (hybrid) joints, fillet joints, etc., in addition to butt joints. [3]


Variants of FSW have been introduced since the initial disclosure of FSW. These include multiple forms of friction stir spot welding (FSSW) [4] and friction stir processing (FSP). [5] Other variants include friction stir additive manufacturing. FSW and the related technologies, FSSW and FSP, may be referred to collectively as friction stir (FS) technologies. Each of these technologies is intended to be carried out below the solidus temperature of the workpiece(s) and is thus considered a local solid-state fabrication process having aspects similar to other forms of wrought metal working processes such as forging and extruding.

Core Competencies

  • Designing (processing, joints, tools, etc.)
  • Modeling (super predictor, etc.)
  • Process Development
    • Purpose Built Equipment
    • Machining Centers
    • Robotic
  • Thermal Management
  • Optimization
  • Evaluating
  • Testing
  • Characterizing
  • Developing
  • Prototyping


1. International Publication Number WO 93/10935, Improvements Relating to Friction Welding, June 10, 1993
2. UK Patent Application GB 2 306 366, Friction stir welding, May 7, 1997
3. European Patent Specification EP 0 752 926, May 27, 1998
4. Examples include: International Publication Number WO 0 128 732, United States Patents 6,601,751, 6,604,667, 6,722,556, 7,562,803, 7,121,451, and 8,444,040.
5. Examples include: European Patent Specification EP 1 162 283 and EP 1 690 627, United States Patents 6,866,180, 6,712,916, 8,220,693, and United States Patent Application US 2005/070374.