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Friction Plug Welding

The I-STIRâ„¢ Plug Welding System is a proven solution for completing closeout self-reacting welds and repairing defective weldments. Engineered to deliver maximum flexibility, our custom plug welding machine solutions can be equipped to perform both friction push and pull plug welding.

A Complete Friction Plug Welding Solution

The I-STIR Plug Welding System (PWS) from PAR Systems is a complete integrated friction plug welding solution, featuring:


  • Precision I-STIR controls, instrumentation, and software
  • Proven independent forge actuator technology
  • Reliable I-STIR hydraulic power unit and hydraulic service manifold
  • Optional multiple degree of freedom weld head manipulator


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Robot performing friction plug welding operation to fill hole in aluminum alloy

Perform Friction Push and Pull Plug Welding

The I-STIR PWS from PAR Systems is a complete integrated friction plug welding solution, featuring:


  • Friction Push Plug Welding: A preferred technique for closing self-reacting weld keyholes and repairing defective welds. After a heating phase, a rotating tapered plug is forced into a tapered hole until a preprogrammed distance is achieved.
  • Friction Pull Plug Welding: Well suited when access is limited primarily to interior surfaces for any filtering or support required for the process. After a heating phase, a rotating tapered plug is pulled into a straight hole until a pre-programed distance is achieved.


In both applications, after the plug preprogrammed distance is achieved, plug rotation is stopped very quickly, and force maintained while the materials cool down. Excess plug material and back side extrusion are then removed.

Why I-STIRâ„¢ Friction PWS Technology

Tight control for consistent optimal plug weld quality

The I-STIR PWS control system is engineered to deliver the precise, closed-loop position and load control required to meet these critical needs. The I-STIR PWS control system integrates three major components seamlessly: an FSW real-time controller, personal computer (PC) running I-STIR PWS software, and a remote pendant.

Weld head and tool of friction stir welding machine

Proven independent forge actuator technology

The I-STIR PWS employs an innovative, high-speed weldhead spindle to deliver the highest levels of precision in position and control force. Standard spindles are fixed axially, but the I-STIR PWS weldhead spindle shaft is also a precision linear actuator that travels along the forge axis. This allows control of plug penetration to be maintained completely by the weldhead.

Manufacturing photo of a liquid oxygen tank after barrel.

Friction process experts

The I-STIR real-time controller and underlying codebase are the product of years of development and close FSW and FPW customer collaboration. It is built on the widely accepted platform and is easily adapted to meet evolving needs. The platform allows for control and sampling rates at 1 KHz or better, essential for driving extremely rapid friction plug welding events.

Benefits of Friction Plug Welding with PAR

  • Supports thick welds
  • Enables more welding of aluminum alloys
  • Improves strength and structure
  • Provides consistent plug weld quality
  • Performs both push plug welding and pull plug welding
  • Extends the useful life of manufacturing components
  • Improves speed and efficiency of advanced manufacturing processes
  • Includes easy-to-use graphical user interface designed for operational ease


See I-STIR friction plug welding in action.

em1 plug weld