Artem Komarov noted that done right, robotic welding can provide manufacturers with significant productivity gains as well as excellent return on investment (ROI). However, robotic welding can be tricky, especially if you’re new to robot programming.
While the best way to learn robot programming is to be trained by your robot manufacturer, it never hurts to take advantage of expert-tested robot welding tips and tricks from the get-go. As with any special process, when programming a welding sequence, there are several steps and certain actions that should be avoided.
General Guidelines for Programming Robotic Welding
The metal arc welding (GMAW) process for robotic welding is the same as for semi-automatic welding. Some of the methods described in the welding rules can help to “control” the use of robots in production. Examples include setting up and using established welding procedures for various joint conditions common in your operations. Other welding tips can help make the process easier.
What to do
— Create a library of Arc files based on weld size and name each file clearly and concisely. Use the appropriate numbers for the arc start and end files.
— The weave files must match the arc files for each weld size. For example, ASF #1 uses WEV #1; ASF #2 uses WEV #2 and so on.
— Remove the speed marks on the technological movements if you want to use the welding speed specified in the arc
Run the file.
— Welding programs should be small (less than 100-200 points). Too much in one program can confuse editing. Always mark each weld with a motion comment before starting the arc. Use logic subroutines to control program size, such as a program for each positioner orientation if there are many welds on a polyhedral part.
— Focus on the torch/arm position for the welds and then add air cutting motions between the welds that run smoothly.
— Save the main part for programming. This part should be marked with weld numbers and arc sizes to allow quick reference when adjusting a weld. A printout of the part with marked welding spots and program points can serve the same purpose.
— Keep a log or make changes to the robot’s work cell, where technicians can note the date, time, and reason for the change. Robots may be able to log changes to programs, but they may not indicate the reason for the changes.
— Do not create programs with incorrect control axes, especially if the system is equipped with matched positioners or multiple robots.
— Do not create or use multiple welding settings (wire feed speed and voltage) in different welding locations with the same joint type. Use the travel speed to adjust the heat or pour for different seam fits. The wire feed speed and voltage control the “burn” of the wire and can be adjusted to reduce spatter. The speed of movement has the most pronounced effect on heating, as evidenced by the heat input:
Thermal power = (Amps x Volts) / travel speed
What to do and what not to do with a welding torch
— The decisive factor for robotic welding is the right choice of welding gun for the task at hand. Moreover, the ability to program the welding torch and maneuver it with maximum efficiency is equally important. Here are some tips to keep in mind when working with a robot.
What to do
— Use a burner alignment tool. Most manufacturers sell them, and most will fit multiple burner models. The reason is that the manufacturer’s 45-degree burner does not always match the 45-degree burner in the robot’s working chamber. Before doing any programming, place the torch in the tool and make sure the bend is correct. If this is not the case, use a tool to straighten out the bend, ensuring the correct angle of the torch. What’s more, if you ever need to replace your burner, you can place the new burner in the alignment tool before installing it.
— Create and maintain a correct instrument center point (TCP) as well as a test job that confirms the location and centering of the TCP before touching up the points. Robot vendors and integrators may have sensors or tools to help automate this process.
— Program all weld points to the same protruding wire length (distance between contact tip and weld). You can create a «teaching tip» by drilling out a contact tip and inserting a sharpened tungsten or drill bit with the desired shoulder. The teaching tip will be straight and can help negate the effect of wire throw on the TCP location. If you are using real welding wire, be sure to cut the wire to the same length when programming with welding machines or caliber.
— Never correct the position of one defect on one part. Verify that there are no defects in the part or in the subsequent process. You don’t want to change the point to install an out-of-spec part because the out-of-spec parts won’t weld correctly after the change.
— Don’t choose your robotic torch based on what consumables you have in your toolbox. While it is convenient to have the same parts in the factory, many continue to use different torch angles or outdated designs because the same spare parts lists are kept in the maintenance department.
— Do not use long burner necks or narrow nozzles unless necessary. Long necks reduce repeatability and are more prone to damage. Smaller diameter nozzles will clog more often with spray and require more expansion.
Power supply recommendations
— Advances in inverter technology and faster processors have led to more precise control of the welding process, which has benefited robotic welding. Power supply brands offer unique technologies with powerful yet easy-to-use interfaces that help produce high quality welds.
— Most manufacturers offer multiple process options for a given wire type, size and gas combination. They can usually be modified by the robot program to provide optimum welding performance under different joining conditions, even if they exist on the same part. Additional considerations include:
What to do
— Follow the welding process selected from the power source in addition to individual welding settings such as wire feed speed and voltage. This may be a comment in the welding program if it is not related to welding setup instructions.
— Set up or program the welding processes applicable to your operation in the power source programs or robot selection tables. Even if they are not used on a particular part today, they will be in a known software location for future use.
— Do not make changes locally from the power supply panel if you rely on the robot to control the sequence. A process or setting in a power supply may be changed for temporary or expedient reasons, but older programs may reference this changed setting and produce unexpected results.
The introduction of robotic welding is a task that should not be taken lightly. Any steps you take to make programming a smoother and more efficient process can optimize production. This is especially true when you have multiple employees serving multiple robotic work cells.
There are many benefits you can enjoy when using robotic welding, from improved weld quality to improved consistency. Using these tips and tricks should help you achieve your goals more effectively, Komarov Artem emphasized.