Implementing a robotic welding system
There are many reasons for companies to consider investing in welding automation — from a desire to improve productivity and quality to the drive to become more profitable and competitive.
In recent years, more. companies have turned to welding automation due to their struggle to find experienced welding operators. The average age of today’s welding operator is 55, and fewer youth are pursuing welding as a career, leading to a deficiency of welding operators nationwide. Companies are also finding, in some cases, that younger welding operators may lack the skills necessary to produce consistent quality welds.
As a result, companies looking to expand their capabilities and attract new business and/or produce new parts are faced with a choice: either hire more welding operators or consider welding automation — or both. It is important to note there will always be a need to employ and train welding operators who can oversee the robotic welding systems.
And though the idea of implementing welding automation can be intimidating, companies can reduce risk and maximize results. Consider these five recommendations.
Step No. 1: Start small
One of the biggest pitfalls of investing in welding automation for the first time is trying to start with too large of a part, thus requiring a large and complex robotic welding system.
Companies should start with a more manageable system that welds simpler parts. Why? There are two main problems with investing in “too much” as a first-time user of welding automation:
- More advanced robotic welding systems —ones that use two robots welding in tandem, for example — are more complicated to program and operate, which exponentially increases the risk of the investment.
- Larger and more complex parts are more difficult to weld robotically. If not tacked up properly, the robot may miss the discontinuities a human welder would otherwise notice and adjust for. As the variation in tolerances stack up on a large part, it may magnify the discontinuity and cause significant quality issues. In this instance, the cost of rework on a large part would be much greater than on a smaller part. There are also fixturing and extra programming costs to consider when rectifying inconsistencies, in addition to the unproductive use of this large capital investment.
In the end, mistakes can happen, so it is best to start with less complex systems and smaller parts that inherently lead to less costly fixes. The old adage “walk before you run” holds very true with first-time robotic welding users.
Step No. 2: Start with simple weld joints and parts
For the best results, companies should start with simple weld joints when first using welding automation. Fillet welds and basic lap joints are both good options, as they are easier to weld successfully.
With simpler parts, it is also easier to control the repeatability of the weld joint location within one half the diameter of the wire — the ideal position for quality results — without the use of additional sensors. If the weld joint is off-center from where the robot is welding, it can result in weld defects, such as lack of fusion.
When first implementing a robotic welding system, companies should also be mindful of gap conditions — the distance between the two parts that make up the weld joint. On a simple fillet weld in which the two parts are touching, the robot will likely achieve a good weld. A good rule of thumb with gap conditions for MIG welding steel is half the thickness of the thinner member of the two pieces being joined. For aluminum welding, the gap should be even less.
As the company matures in its knowledge and use of welding automation, such gap conditions should be a matter of ongoing consideration.
Step No. 3: Ensure smooth and accurate upstream fabrication
One of the keys to success when using welding automation is a repeatable upstream fabrication process.
Remember, a robotic welding system cannot adjust accordingly like a human welder (at least not without the addition of costly and time-consuming sensors), so companies cannot load non-repeatable parts into the fixturing and expect quality parts to result. Instead, the end goal is to have a steady flow of consistent parts entering the weld cell so the robot can execute accurate welds, every time. When possible, companies should consider laser cutting parts to maximize the accuracy of parts. This process allows companies to achieve “gold in, gold out” versus “junk in, junk out.”
In terms of the overall workflow, it is important not to produce more parts upstream than a robot can handle. It is equally important that the robot doesn’t sit idle while waiting for parts. Conducting an assessment or time trial of the workflow can ensure companies are optimizing their efficiencies.
Ultimately, in order to maximize the return on this large capital investment, a robotic welding system should produce roughly a 3-to-1 gain over what a human welding operator can achieve. The flow of parts into the robotic weld cell should support this goal.
Step No. 4: Slow down the process
Again, first-time welding automation users should take the “walk before running” approach. Never expect the robotic welding system to work perfectly or at full speed on the first day. It can take time for the system to function at its peak performance.
One mistake companies may make is running the robotic welding system at full speed on the first part on the first day, which can cause a multitude of problems. For example, if there are gaps in the parts or parts along the fixturing that are misaligned, companies run the risk of crashing the robot at a high speed. This can damage the gun and/or robot arm — a costly mistake easily avoided by slowing down the process at first then slowly ramping up the speed.
It is common practice to start at 25% speed to ensure there are no crashes. After the successful completion of three or four parts, companies can increase the speed to 50% and, again, ensure there are no small crashes or inconsistencies in the completed part. Once the system is indisputably functioning properly, companies can increase the robot’s speed and the number of parts it welds incrementally until it is functioning at 100% of its capacity.
This practice holds true even when placing a new part with a new fixture in a well-worn robotic welding system. Always start slowly and build up to 100 percent speed to avoid crashes and costly rework.
Although all robotic welding systems either have collision detection software or an external clutch that protects the gun and robot arm in the event of a crash, eventually some component in the system will suffer from the impact if the system repeatedly crashes. In addition, companies incur downtime to reprogram the tool center point each time a crash occurs.
Step No. 5: Maximize the investment
Companies need to remember that part of the investment in welding automation includes having or hiring employees who will oversee the process. Employing the right people and providing the right training so they can operate the system properly will ensure its success and profitability.
Beyond in-classroom training, companies should explore the onsite training programs many welding equipment manufacturers offer. For this reason, companies can also benefit from purchasing their welding automation system from a manufacturer who offers after-sale support and expertise in robotic welding. These manufacturers can help program the robot to address any nuances of the specific parts being welded by the new system, and they can help troubleshoot any issues that may arise. Robotic welding has its own set of subtleties and companies that don’t specialize in robotic welding may overlook or ignore these to the company’s detriment.
Having the right resources — both employees operating the robotic system and the equipment manufacturer who is providing technical and training support — is critical. It can maximize the investment, helping companies ensure the success of their automated welding system from start to finish.