So you want to buy a robot?

Robotic welders are fantastic machines. Capable of incredible speed, accuracy, repeatability and fluid motions around parts that just can’t be replicated by hand in some instances. Their ability to handle weld procedures hot enough to melt your helmet visor without issues and do this day in, day out makes them a valuable asset to any production facility where quality and efficiency is key.

To make a robotic welding application successful though, requires a few considerations to make sure the robot is operating within its optimum efficiency. These typically fall into three categories:

What you feed it

How you hold it

Who is responsible for it?

What you feed it

Modern robotic welders are incredibly fast and precise. Their typical repeatability is measured in hundredths of a millimeter. This means that when we program a point for the robot to go to, it will be able to get within a few hundredths of a millimeter of this point EVERY TIME. This is one of the truly great things about modern robots, but it brings with it a potential problem. If the parts that you feed to the robot are not repeatable in the same order of magnitude, the quality of the welds will be difficult to guarantee and reproduce.

 

The usual rule of thumb with a robotic welder is that we want repeatability within half the diameter of the welding wire (depends on the wire used). This means that we are usually looking for within 0.45mm (0.9mm wire) or 0.6mm (1.2mm wire) of its original spec. This is also dependent on the material being welded and the welding procedure used. There is also the aspect of joint variation and repeatability that needs to be considered. It is possible to introduce other techniques to widen the band of operation (weaving, touch sensing, laser seam trackers etc) but these should always be a last resort. Far and away the best option is to fix upstream processes that give higher quality and more repeatable parts to the robot. When this is done, the robot can be much more efficient in its programmed movements and this allows it to achieve shorter cycle times and ultimately produce more usable parts in a shorter time period.

How you hold it

The considerations for how you hold it are very similar to the “What you feed it” side of things, in that you need to have a way of holding your parts that keeps a good repeatability to allow efficient movements of the robot. Added to this is also how accessible the welds are to the robot when it is held. You could have a really solid jig system that gives amazing repeatability, but if the robot cannot physically reach the welds you are asking it to perform, then that is all for nothing.

Tooling is an artform in itself, hence why there are quite a few companies that specialize only in this highly sought after skill. Good tooling is repeatable, easy to load and unload, while providing good electrical conductivity to the part (arc welding uses electric currents to generate the heat) and stopping the part from warping when the heat is introduced. This is a big list of demands to account for, and as such, good tooling can be very expensive (for some jobs, the tooling costs as much as the robot). The complexity of the parts plays a large part in the type of tooling required, as does the type of weld joints that need to be operated on. Having said all this a great way to start your journey with robotic welding is to present pre-tacked parts for the robot to weld out. This is also a good approach when small batch sizes are considered. The lessons learnt from this approach also make subsequent tooling and product design more robust and more successful.

Who is responsible for it

The world’s most expensive robotic welder will only ever be as good as the person who programs and maintains it. This may sound obvious, but it is probably the single biggest factor in the success of a robotic arc welder. The robot is capable of incredible speed, accuracy and repeatability as mentioned before, but it can only do those between points that someone has programmed. Programming a robot to go through predefined points is relatively easy, and with some training basically anyone can do it. Knowing where to put those points though is another story. The angles, speeds and welding parameters required to produce a good product mean that a good welder is the best person to be programming the robot. They inherently know where they want the torch and they can put all that incredible knowledge to work in a way that human frailties and inaccuracies are not present.

All systems, whether robotic welders or space telescopes, have teething issues or problem that occur during use. To rectify these in the shortest amount of time is the ultimate goal for robotic welding system maintenance. Every minute of downtime, means parts that aren’t being produced, so keeping the system in a productive state is paramount. We find that the most successful systems have a person assigned to be responsible for the overall process involved with the robot. They are held accountable for the robots productivity and throughput and have a vested interested in getting the most out of the system.

Inevitably as time goes on, the system will be utilized more and more and smaller incremental gains will be pursued to get the maximum advantage from it. One way to optimize the robot is sometimes to redesign the parts slightly to give easier access to the welds or change some of the joints to be more forgiving with the tooling etc. Experience with the robot will show the optimum ways to join the parts and it all ends up being part of the overall continuous improvement process.

We at Lincoln Electric Automation exclusively concentrate on welding automation. We always consider the weld requirements first and foremost, and work back from there. As opposed to applying predesigned general automation solution to the welding application. Although this sounds the same it is vastly different, and the results we achieve reinforces our approach. We are part of the Global Lincoln Electric Automation Division, and we are here to partner with our customers through the journey to success through welding automation. Being part of the biggest welding company in the world also means that we have access to technologies and knowledge that no other company can offer.

Please contact us at Lincoln Electric with any questions and we would look forward to working with you on your requirements to optimize and modernize your welding operations.

It always starts with the WELD !