Over the past few years, the manufacturing industry has seen an increasing shortage of welders available in the market. The issue is compounded by reduced interest among the younger generation of workers in learning manual welding skills. Further challenges are created for welding departments when increased upstream efficiencies produce bottlenecks in sheet metal fabrication. Seeking to solve these production problems, more and more North American metal fabricators are investigating the possibilities created by easily integrated automated robotic welding.
When compared with a more traditional manual welding process, robotic welding can improve the efficiency and increase the productivity of welding operations. However, robotic welding technologies are not meant to replace existing manual welders. Rather, the technology helps manufacturers keep current welding staff by providing the technology they need to fulfill the increasing requirements for part volume and welding quality. Automated robotic welding helps transition the welding staff into the new world of manufacturing.
The primary method of calculating the ROI of robotic welding systems is based on the percentage of arc-on time, which is typically three times the throughput of a good manual welder. In other words, based on experience, a manual welder usually has 20 to 25 percent arc-on time, but could easily drop below this range considering the time needed for preparing the part (tacking, aligning and adjusting parts, etc.).
When combined with a robotic welding station, a welding operator can easily reach 75 percent arc-on time due to the speed and consistency in performing the welding process. In this process, while the robot is welding on one station, the operator is unloading a newly welded part and loading a fresh part to keep the welding process flow moving.
Once the parts are loaded, the robot shifts to the next station in a matter of seconds and starts the process again with minimal downtime. This combination helps manufacturers improve their welding throughput from 25 to 75 percent and adds a process with an equal or better welding quality that promises a fairly short ROI.
Overcoming obstacles
Considering all of these advantages, the main question remains: what is holding back the sheet metal industry from widely utilizing robotic welding? The answer to this question lies within the additional investment needed for training and in personnel for programming and operating the robotic welding systems. In traditional robotic cells, instructional costs can easily reach $10,000 per person considering the long one to two weeks of training needed for operating such systems and adding in the lost wages and productivity on top of that.
Thus, there is a vital need to make the robotic operation process easier, cheaper and less risky. The need for prior knowledge of robot programming or complex CAD files for programming must be eliminated, the operator training shortened, and the costs and risks must be reduced for manufacturers to enter the world of robotic welding.
Collaborative robots, or cobots, have been introduced recently as a solution to make robotic welding easier, and overcome most of the challenges mentioned earlier. Cobots are lighter, slower and have lower capacity compared to traditional robots, but they do offer several advantages. Cobots have better portability, fewer safety requirements and, most importantly, easy programmability by directly moving the robot torch to the right spot manually by hand and saving the positions.
As opposed to traditional robots, cobots were developed with the idea of closely collaborating with the human body, offering easy understanding of the robot movements and behavior, which leads to easier and faster programming. Using cobots, machine manufacturers, including TRUMPF, are able to reduce the cost of developing entry-level robotic weld cells and decrease the cost and time required for customer training.
One of the latest welding technologies introduced by TRUMPF is the TruArc Weld 1000, which utilizes the cobot and integrates traditional MIG welding technology. This weld cell was developed with a focus on high-mix and low-volume production to assist sheet metal manufacturers interested in an entry-level welding technology that is both quick to program and easy to learn. This reduces the initial training costs and time and assists any current welding staff, even those with minimum knowledge about robot programming, in getting started without lengthy training.
Time studies have shown the cell can reduce the programming time for a part to just a few minutes using the cobot versus a few hours using a traditional robot.
Easy programming
Programming with the TruArc Weld 1000 happens in four easy steps: 1) moving the robot torch to a safe approach position above the part and then saving this point using the “way-point” bottom on the torch, 2) moving the torch to the ideal spot to start the welding process and saving this position as arc-on point using the “arc” bottom on the torch, 3) moving the torch to the end of the weld seam and saving this position as arc-off point using the “arc” bottom, and 4) moving the robot torch to a safe retraction point that has enough clearance with the part and saving this point using the “way-point” bottom.
Moreover, using this cell, the robot is on track with two operation points at each end of the track. The dual-station mode splits the 2-m table into two sections with 1 m length. Using the dual-station mode, the operator can program one station and copy the program to the other station without the need to recreate the program. In production, while the robot is welding on the first station, the operator is able to unload or load the other station, which results in parallel production.
Cold metal transfer (CMT) technology improves the weld bead aesthetics with controlled metal deposition and low heat-input. The digital process control detects a short circuit and then helps to detach the droplet by retracting the wire. During welding, the wire moves forward and is pulled back again as soon as the short circuit occurs. As a result, the arc only introduces any heat for a very brief period during the arc-burning phase. The short circuit is controlled, and the current is kept low, resulting in a spatter-free material transfer.
Cold metal transfer is an exclusive technology offered by TRUMPF on the TruArc Weld 1000. The arc length is detected and adjusted mechanically. The arc remains stable, even if the workpiece surface condition or the weld speed changes. Therefore, CMT can be used in variety of welding positions.
Flexibility is a key consideration for manufacturers in today’s continually changing environment. Standard configurations, such as those found on the TruArc Weld 1000, mean the machine can be installed by a customer without difficulty. It also makes it easy to relocate the machine within the production facility if there is ever a need to change the layout of the production flow.
Robotic welding can help alleviate labor shortage and production challenges, but it is important to find the right one for the manufacturing environment. For sheet metal fabricators with a focus on high-mix, low-volume production, the TruArc Weld 1000 machine is a great option that makes it easy to enter the world of robotic welding. The hope is that cobot weld cells will help relieve small to medium-size job shops and OEMs from some of the challenges they face in their welding departments.
