Conventional Guns on Through-Arm Robotic Welding Systems: When to Make the Choice

Through-arm robotic welding systems are becoming increasingly common in the industry as more equipment manufacturers turn to the development of this style compared to conventional robots. However, there are some applications where it is better to use a conventional robotic gun for these systems, instead of the through-arm gun that is typically chosen. The good news is that most through-arm robotic welding systems allow for mounting either type of gun, providing more options and flexibility depending upon the needs of the application. And while the choice of gun is sometimes an afterthought, it can significantly impact efficiency, throughput and quality of the finished weld. Choosing the best option for the job up front is key.

CONSIDERATIONS IN CHOOSING ROBOTIC GUNS
As the name suggests, the power cable assembly of a through-arm MIG gun runs through the arm of the robot, as opposed to over the top of the arm like in a conventional gun. Because of this design, the through-arm gun style is often more durable because the power cable is protected. However, because conventional guns can be used on either a through-arm robotic system or a conventional robot, they can sometimes offer greater flexibility and can be used with more robot makes and models. There are numerous factors to consider when making the choice between a through-arm gun and a conventional robotic gun for a through-arm robotic welding system, including:

• Available space and weld cell layout.
• Reach and access to weldment.
• Type of material being welded.

BENEFITS OF CONVENTIONAL GUNS
Conventional style guns, which typically offer a longer neck, can provide more flexibility in accessing or reaching certain weldments, whereas through-arm guns may have difficulty reaching around fixturing or tooling in some cases. In applications where a through-arm gun is installed and it doesn’t reach the weldment as needed, a conventional gun can be swapped in for access purposes. In addition, conventional guns are often a good choice in smaller, more modular weld cells that feature short-armed robots. Through-arm guns may not work as well in these situations because there is not as much cable, which means the robot doesn’t have as much slack for articulation. Also, because of the way the cable lies in a conventional gun, the bend radiuses of the cable are much larger than in through-arm guns. For example, wire feeding is a major contributing factor to poor weld quality when welding aluminum, so tight bend radiuses are not recommended. This makes conventional guns a good option when robotic welding aluminum.

Uptime and throughput are also critical in robotic welding applications, and maintenance is a key factor that impacts productivity, downtime and costs. Conventional guns often provide easier maintenance because everything is outside of the arm, allowing for parts to be changed or repaired quickly to minimize downtime. Another benefit of conventional guns is they tend to be more cost-effective to purchase and can be installed much faster, saving time and money in setup.

WHEN TO STAY WITH A THROUGH-ARM GUN
Through-arm guns provide their own advantages when matched with a through-arm robotic welding system. In applications that require plunging deeply into a fixture or part, a through-arm gun is often a better choice. Think of a through-arm gun as an extension of the robot arm. This extension allows it to access different areas within the part being welded, depending on the application. And because the cables are more protected on a through-arm gun they tend to last longer overall, which helps reduce replacement costs. The through-arm design naturally protects the power cable and makes it less prone to snagging on fixturing, rubbing against the robot, or wearing out from routine torsion.

BEST PRACTICES FOR PERFORMANCE
With either a conventional gun or a through-arm gun, there are some common best practices that can contribute to success in robotic MIG welding. First, it is critical that the cable is never under tension when using a through-arm gun, to help prevent premature cable failure. Cable tension is visible on a conventional style gun but not on a through-arm gun since the cable runs through the gun. This makes proper setup especially important with through-arm guns. It’s also best to use a cable management system when using a conventional gun to ensure there isn’t too much slack in the cable. With too much slack, the cable will rub on anything around it and possibly catch on fixturing. When a robot moves at production speed, it can break the cable or fixture.

Keep these factors in mind, along with joint access requirements and weld cell layout, when making the gun choice to help improve throughput and productivity.