What is Sigmund?

Sigmund is an opto-electronic device which checks or corrects the position and condition of tools such as MIG welding torches.

How does Sigmund improve weld quality?

  • If the welding torch has deformed due to thermal stress or has been mechanically bent, Sigmund can measure this offset and raise an alarm if it is out of tolerance.
  • Sigmund can send a correction to the robot, keeping the welding path constant despite the mechanical damage.
  • To combat on-going quality issues and aid continuous improvement, Sigmund can log its measurement results to a PC.

How does Sigmund work?

The robot drives the tool into a 50 mm diameter measurement area. By tracing 30,000 light beams across it, the position of the tool can be determined to an accuracy of 50 microns in under one second.

Why is measurement speed important? The single or dual beam systems typically offered by robot manufacturers require the robot to make a number of moves to take a measurement. The multi-beam system used by Sigmund is fast enough that the measurement can happen while the product is being transferred into and out of the cell, which does not cost cycle time. So a measurement can be made before every part - the system is stopped from making a single bad part.

Doesn't offsetting the Tool Centre Point sometimes mask the root cause of problems? Offsetting the Tool Centre Point would mean that if the torch were getting regularly knocked this would not be obvious from the quality of the welded items, masking the problem. However, if this is a potential risk, Sigmund can be configured not to apply the offset. It simply checks that the misalignment is within a user-defined tolerance, and raises an alarm if the torch is beyond this tolerance. Where Sigmund is configured to apply the offset, limits can be placed on the total cumulative offset.

How does Sigmund's logging feature help to find the root cause? Sigmund can connect directly to a corporate PC network and log the results of the measurements in an accessible format. This provides further tools to help find the root cause of problems, and can aid traceability of parts if a part identifier is logged along with the time stamp and measurement.

What other weld quality issues can Sigmund help with? Sigmund can be configured to check for a number of potential torch issues, such as

  • contamination on the welding tip
  • concentricity of the wire and shroud
  • presence of push-on shrouds which sometimes get knocked or are missing.

How can Sigmund be applied to milling processes? Sigmund is able to automate the definition of the Tool Centre Point ("6 point TCP") - this is usually carried out by visually aligning the tool to a pointer, with the inherent lack of repeatability of the human operator. When a mill is replaced, the length can be automatically checked by Sigmund, and the path corrected appropriately.