The SmartDress Solution

Resistance spot welding is the most commonly applied process for joining thin metal sheet in automotive body structures, with a typical family car containing up to 5000 spot welds. The spot welding process offers a high level of reliability with modern welding systems able to accurately control and monitor spot welding process times, currents and forces.

However one aspect of the spot welding process that is not tightly controlled is the wear of the welding electrode tips. Zinc coated steels are the most popular car body material, but zinc rapidly degrades the electrode to the point where maintenance is required to ensure an adequate weld quality is produced. Electrode wear can be repaired by a technique known as 'tip dressing' where a mechanical cutter removes material from the tip face repairing any damage and returns the tip to its optimum geometry. Today nearly all modern automotive spot welding lines run production with automated tip dressing, but even these systems do not offer a complete solution:

  • Problems with electrode tip maintenance remain the number one cause of stoppages on car production lines
  • Conventional electrode tip dressers use mechanical 'cutters' that remove a large quantity of copper, resulting in rapid consumption of expensive copper electrodes
  •  In the production line start-up phase all tip dressing schedules must be manually programmed, tested and iteratively optimised. This operation is labour intensive and the optimisation phase can take several months before the line is ready to run at full production output

SmartDress is a novel new approach to electrode tip dressing comprising a complete automated solution to all the challenges faced when setting up and maintaining a resistance spot welding process. The SmartDress system comprises five elements, including 3 totally new innovations:

  1. A new approach to electrode tip dressing using an abrasive to clean electrode faces with a minimal removal of copper, greatly extending electrode production lives
  2.  An optical sensor able to monitor the electrode condition providing vital data concerning the state of wear
  3.  A computerised control system able to process data from the optical sensor to determine the level of electrode cleaning required. The control system can also optimise dressing schedules adaptively controlling electrode maintenance frequency
  4.  A mechanical dresser designed to minimise copper removal during tip dressing
  5.  An automated tip changer able to replace worn tips during production without the need for a line stop and manual intervention


Impacts of the SmartDress system:

Introduction of the SmartDress system into a production line can have significant impact on the resistance spot welding process:

  •  Increased production life of electrodes achieved by minimal material removal using the abrasive dresser development. Initial results show an increase of 3 x the production life when welding zinc coated steel
  •  Regular electrode maintenance using abrasive dressing allows for economical spot welding of aluminium as copper consumption is dramatically decreased
  •  Automated optimisation of electrode tip dressing frequency during production line start-up phase
  •  Monitoring and adaptive control of the electrode during spot welding production, able to adapt electrode maintenance schedules to compensate for unexpected electrode damage
  •  Control of spot weld quality through monitoring and maintaining welding electrodes improving quality assurance of the production line