The highest population of robots is in the area of welding. Spot welding is a very tiring job for operators and the productivity is very low. While spot welding is mostly restricted to automotive BIW (Body in White) applications, MIG welding is most popular for sheet metal and tubular fabrication. MIG welding applications require skilled labour. For robotic welding, the input components need to be very consistent and clamping fixtures need to be thoughtfully designed. Part manipulators such as 2 axis Rotary positioners are an integral part of robotic welding. They are needed to improve the accessibility and to achieve proper torch angles.
One of the issues faced by customers is the inconsistency of the input materials. Typically components prepared using laser cutting and CNC bending have better accuracy, but when it comes to thicker sheets above 4mm, there is still a lot of variation.
The following advanced sensing technologies are available to compensate for the variation in components,
- Touch sensing
- Arc sensing
- Laser seam tracking
Using these methods, the feedback is provided to the robot and the path is automatically adjusted to make up for variation. These options add cost and are to be used as a last resort and for longer seams. The best method is to improve the input component quality by improving the upstream processes and ensuring proper fit up.
Welding power sources are expensive. The typical up time of a manual welder is around 50%. With Robotic units, the uptime can be as high as 85%. So the same amount of welding can be done with less power sources, fixtures and floor space. A huge savings in the connected load can also be realized.
Typically a single robot can be used to service 2 or 3 workstations. So while the robot is welding, the operators can complete the part fit up at another station safely. 7th axis tracks can be used to extend the reach and utilization of the robot.
Operator Health & Safety
In a robotic system, the operators are completely isolated from the smoke and the hazardous light emitted during welding. A properly designed exhaust system can provide a cleaner environment.
Another area where robotic welding helps is spatter control. Spatter can be drastically reduced by using proper torch angles and fine tuning the parameters. If spatter is reduced, the components can be directly sent for downstream operations such and machining and powder coating. The labour required for grinding can be indirectly saved.
Consumables/Material savings can also be realized, as manual welders tend to over weld. Over welding also leads to distortion.
Quality and consistency
The quality of the part is drastically improved.
Welding robots require constant maintenance and care, so that they provide the above mentioned benefits. To improve the uptime(arc-on time) , the following accessories are strongly recommended for a complete system
- Wire snipping stations
- Torch cleaning stations
- Crash boxes or Clutch mechanism to stop the robot in case of an accident
- Automatic TCP correction tool
For welding, we offer complete solutions with component fixturing and safety interlocks. The required operator training can be provided, so that simple tasks such as program touch up and parameter adjustments can be done by the technicians. Our solution at one of the OEM’s involves an OH Gantry system for welding large sheet metal components used for textile machinery manufacturing.