Not all gas metal arc welding (GMAW) guns are created equal. Yet guns are often considered a commodity when purchasing a GMAW system. More costly components such as the power source, wire feeder and shielding gas generally take precedence and the gun often becomes an afterthought. Unfortunately that afterthought can lead to poor weld quality and higher operating costs.
Because the GMAW gun is responsible for consistently delivering the current, the electrode and shielding gas to the weld puddle, it plays a critical part in achieving quality welds. Closely examining your application and selecting a gun specifically designed for your needs can be an easy and cost effective means of improving that weld quality, increasing productivity and lowering your operating costs.
The first question to ask is: Am I using too much gun? A common misconception dictates that if a welding procedure calls for 400 amps, then you need a gun rated at 400 amps and 100-percent duty cycle. A welding operator could certainly weld at 400 amps for eight hours straight and never set that gun down, but in reality, movement of parts, tacking and other labor attribute to a day's work. In fact, the average "arc-on" time for a welding operator over an eight-hour day is roughly 45 minutes to one hour.
You may be able to buy a smaller, less expensive gun with a lower duty cycle rating and still achieve the same results. For example, switching from a 400-amp gun (100% duty cycle) down to a 300-amp gun (100% duty cycle) can often provide equal performance. However, switching to a smaller gun can lower equipment costs (lower amperage guns cost less) and it can also reduce operator fatigue and downtime-less gun means less weight, better maneuverability and increased comfort. A smaller gun can even help establish a healthier workforce and save money by reducing workers' compensation claims for injuries such as carpal tunnel syndrome, which is often associated with using heavier guns.
Using shorter power cables on your gun can also help minimize downtime and lower costs. Shorter power cables are less expensive and help prevent wire feeding problems by minimizing unnecessary coiling. Using the shortest power cable possible for your application-one that will meet your amperage and duty cycle requirements-can also offer better maneuverability for your welding operators.
GMAW Gun Components That Can Save You Money
Amperage is not the only cost-saving consideration related to choosing the right GMAW gun for your application. Several components on a GMAW gun can translate into savings when given careful consideration.
|Choosing the right neck option for your GMAW gun can help you weld expertly in narrow or out-of-position joints and can save money for costly specialty guns.
The Back End
Begin with a close examination of the power pin that connects the gun and power cable to the wire feeder. A loose connection between the gun and the feeder can cause higher electrical resistance throughout the entire system, leading to overheating that can damage either the gun or the wire feeder. It can also cause gas leakage and poor conductivity that could lead to an erratic arc and poor weld quality. A heavy, sturdy power pin designed to seal the connection tightly helps prevents these problems and the costly downtime and rework associated with them.
Secondly, choose a gun with a rigid strain relief at the connection between the power cable and the wire feeder. It can prevent the power cable from kinking and provide better wire feeding, a more stable arc and better quality welds-each factors that add up to less rework, more welding time and better productivity.
It is also important - specifically in shops that run different brands and styles of feeders - to select a gun with multiple, interchangeable plug options. Having a gun that can be matched with different feeders allows you to standardize on one style of GMAW gun throughout your shop and stock only one brand of accompanying consumables. This standardization helps reduce equipment costs and minimize inventory, not to mention the costly time that goes into stocking and maintaining numerous parts.
Liners are one of the most critical components of a GMAW gun: many feeding problems originate with this component and its replacement can be among the more expensive causes of downtime and/or maintenance issues. The liner can also be a source of gas leakage, which wastes costly shielding gas and leads to insufficient protection of the weld puddle (leading to rework and added clean-up).
First, make sure that there is a good gas seal and/or solid o-ring connection at the back of the liner to help prevent gas leaks. Also choose liners with a durable jacketing or coating to prevent additional gas loss through the steel liner coils.
Next, select a liner designed specifically for your diameter of wire. Liners that are either too large or too small can cause poor wire feeding that may lead to an erratic arc and poor weld quality. The liner size needs to match wire size, usually within a specific range; for example, you could use a .035-in. wire in a .035-in. to .045-in. liner. Maintaining these parameters will help ensure proper wire feeding and improved weld consistency.
The Power Cable
A cable that is too light for your application can cause the gun to overheat and may lead to poor welding performance, whereas a cable that is too large can be cumbersome and cause clutter on the shop floor. A good rule of thumb is to use the smallest and shortest cable possible without limiting your welding needs; smaller cables reduce operator fatigue, minimize clutter and help prevent excessive coiling that can lead to poor wire feeding. As with other components, make sure that the power cable fits tightly into the wire feed system to maintain proper conductivity.
Triggers are the only moving part on a GMAW gun that can fail due to mechanical motion. Look for a strong, reliable trigger that is easily serviceable to help minimize downtime for component changeovers. Also, choose a gun that gives you the most appropriate trigger option for your application: standard, locking, dual pull, dual schedule switches are all available through most manufacturers. These options allow your welding operators to work with the trigger set-up that best suits them and the application, and will further increase productivity by making welding more comfortable.
Neck and Handle Options
GMAW guns are available with fixed, rotatable and flexible necks of different lengths and angles to provide flexibility when welding in various positions or tight quarters. Rotatable necks, for instance, allow you to weld out-of position more comfortably without changing your gun handle or sacrificing quality. Flexible necks can be easily adjusted to fit different positions and save time and money for changing out and/or inventorying expensive specialty guns for a given application. Also, choose a neck with good armor (hard plastic or metal) to protect it from damage that could lead to shorts and failures in the gun.
When looking at handle options, consider lightweight, comfortable styles that will meet your amperage/duty cycle rating needs. Similar to the power cable, a smaller handle makes it easier for you to weld. Also, a ventilated handle can reduce heat and increase your comfort and productivity.
|Selecting more expensive, longer lasting consumables can add up to long-term cost savings.
Consumables (nozzles and tips)
Less expensive consumables do not always translate into cost savings - ultimately, you get what you pay for. By selecting a consumable based on longevity instead of price you can reduce costs for replacement parts and for changeover time. You will likely spend more money upfront for such consumables, but more durable consumables can help reduce overall operating costs in the long run by increasing productivity and reducing downtime. It is also important to look for heavy duty tips and nozzles that provide good conductivity and gas coverage to help ensure good arc starts, less spatter and less rework and clean-up.
GMAW guns are an important and often overlooked component and should be a major factor when selecting a welding system. A gun should be durable, easy-to-use and customized to your specific application and offer the lowest amperage necessary to fulfill welding parameters. The right GMAW gun offers less downtime for maintenance, component changeovers or operator fatigue, and more consistent welds for better productivity. Most importantly, each of those factors leads to reduced operating costs. Take the time to fully investigate your gun options and begin improving your bottom line today.