Identifying the causes and fixes for robotic welding troubles
Trouble 3: Poor consumable performance and/or premature failure
Causes: The poor performance or premature failure of consumables—including nozzles, contact tips, retaining heads (or diffusers), and liners—can be caused by a number of issues, including spatter or debris buildup, loose connections, or improper liner installation.
Remedies: Visually inspect the consumables for signs of spatter or debris buildup during routine pauses in production. If signs of either occur, replace the consumables. Also, if utilizing a nozzle cleaning station (also called a reamer) and buildup seems to be a problem, check that this equipment is working properly and that the welding operator has programmed it to clean at a frequency that is appropriate for the application (see no. 5 below for more information). It may be necessary to increase the frequency of cleaning and/or anti-spatter spray application throughout the programmed welding cycle.
Next, check that all connections between the consumables (and robotic MIG gun neck) are tight. Loose connections increase electrical resistance, causing the consumables to generate additional heat that can shorten their life span and/or cause them to perform poorly.
Issues with the contact tip, particularly burnbacks, also are not uncommon. These are often the result of a liner being trimmed too short. Welding operators should follow the manufacturer’s instructions for liner trimming and installation, and when possible use a liner gauge to confirm the correct liner length. There are also spring-loaded modules available that work in conjunction with a front-loading liner to help minimize issues if a welding operator cuts the liner to an incorrect length.
These modules are housed in the power pin and put forward pressure on the liner after the welding operator installs it from the front of the gun. They allow up to 1 in. of forgiveness if the liner is too short.
Trouble 4: Premature cable failure
Causes: Premature power cable failure, on either a through-arm robotic welding system (where the cable feeds through the arm of the robot) or in a standard robotic welding system, can be the result of incorrect programming that results in aggressive movements. It can also occur when using the incorrect power cable length.
Remedies: Protect against premature cable failure by ensuring that the robot is not moving too quickly or abruptly. Programming that causes aggressive movements can make the power cable flop and/or rub against the robot or tooling. In some cases, it can also cause the cable to catch on components, leading to wear. All instances can cause premature failure.
Also, be certain that the power cable is neither too long nor too short for the robot. If the power cable is too long, it may kink or get pinched by the robot’s arm. If it is too short, the power cable may stretch beyond its capacity during routine robotic movements, leading to greater wear. When in doubt about the proper length of power cable to use, contact a trusted MIG gun manufacturer, welding distributor, or robotic integrator for assistance.
Trouble 5: Nozzle cleaning station isn’t operating properly
Causes: The most common peripheral added to a robotic system is a nozzle cleaning station or reamer, which, as its name implies, is responsible for cleaning the nozzle (and other front-end consumables). This cleaning occurs during routine pauses in production, and any issues with it typically relate to one of three factors: the position between the reamer and robotic MIG gun nozzle, poor anti-spatter solution coverage, or a dull cutting blade.
Remedies: If the reamer doesn’t appear to be doing its job, check that the taught position of the robotic MIG gun is exactly perpendicular to the cutting blade on the reamer. Misalignment of the nozzle can lead to partial cleaning and excessive spatter buildup.
Reamers are typically paired with a sprayer that coats the nozzle with anti-spatter solution. Check that the sprayer is full, the location is correct, and the anti-spatter solution properly coats the nozzle. The nozzle should be slightly damp on the inside and outside and covered to within three-quarters of an inch from the bottom of the nozzle. Adjust the location of the spray as necessary to achieve these results.
Lastly, be certain the proper cutting blade is in place and is sharp.
Remember, taking the time to know how to troubleshoot common problems in the robotic welding operation can mean the difference between costly downtime and consistent, productive arc-on time.
Lloyd Steed is product manager of core products for Tregaskiss, www.tregaskiss.com.
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