In welding, poor wire feeding is a common challenge – one that can be extremely costly for an operation and take a toll on productivity. From the downtime for troubleshooting to faster wear and replacement of consumables, wire feeding issues such as birdnesting, burnback and gun liner clogging can have a significant impact on the bottom line.
There are many potential causes of poor or erratic wire feeding. It can stem from the style or size of gun liner being used, the contact tip size, the gun and whether it’s coiled, or other factors. While finding the cause of the problem can be complicated, the solution is often simple. To best troubleshoot the problem, start by checking for possible issues in the wire feeder and then work toward the front of the gun to the contact tip.
Adapters and guides
There are numerous issues related to the equipment that can cause erratic wire feeding. If the drive rolls don’t move when the gun trigger is pulled, it could be a feeder relay malfunction or broken relay. Consult the wire feeder manufacturer in this case.
No response when pulling the gun trigger could also stem from a broken control lead. Control leads can be easily tested with a multimeter to see if a new cable is needed.
In applications where an adapter is used to connect the gun to the wire feeder, a poor adapter connection could also be the source of feeding problems. Check the adapter with a multimeter and replace it if it’s malfunctioning. Multimeters can also be used to check trigger switches, which can cause feeding issues if they are worn, dirty or damaged from the gun being dropped.
In addition, an improper guide tube installation or improper wire guide diameter can cause wire feeding issues. The guide tube is used between the power pin and the drive rolls – typically when there is an adapter being used on the feeder – as a way to keep the wire feeding properly from the drive rolls into the gun. Be sure to use the proper size of guide tube, adjust the guides as close to the drive rolls as possible and eliminate any gaps in the wire path to avoid feeding problems.
Wire guides are used between the two sets of drive rolls inside the feeder, guiding the wire from one drive roll to the next. These must be properly sized for the wire to avoid problems with feeding.
Drive roll considerations
The use of incorrect drive rolls can be another common source of erratic or poor wire feeding. When it comes to selecting the right drive rolls, there are several best practices to keep in mind.
- Drive roll size should match wire size – a 0.035-in. wire needs to be paired with 0.035-in. drive rolls.
- Choosing the right drive roll style depends on the type of wire being used. The types of drive rolls – V-knurled, U-knurled, V-groove and U-groove – offer pros and cons depending on the wire type. A solid wire is typically used with smooth drive rolls, for example, while a U-shaped drive roll in smooth or knurled tends to work better for flux-cored and metal-cored wires. For additional context, the groove term refers to the geometry of the shape in the drive roll while the knurled term references the finish inside the groove.
- Setting the proper drive roll tension is important to ensure pressure on the wire is sufficient to push it through without changing its shape or fracturing it.
- Inspect drive rolls every time a new spool of wire is put on, and replace them as needed.
An additional note on drive roll styles: Take care when setting the tension on knurled drive rolls with cored wires. While the teeth of the drive rolls can help push the wire through, setting the tension too high can result in the teeth fracturing the thin column of the wire, causing birdnesting in the wire feeder.
When using knurled drive rolls with solid wires, which is sometimes acceptable, proper tension adjustment is critical. There should be enough tension to push the wire through the cable, but not too much tension because it will cause the knurled teeth to dig into the wire and create shavings that can clog the gun liner.
In applications where the welding operator is having trouble feeding cored wire, it can be helpful to use a U-shaped smooth drive roll on top with a U-shaped or V-shaped knurled drive roll on the bottom. The teeth on the bottom drive roll can help push the wire through, while the smooth drive roll on top helps protect the wire shape.
Check the liner
Gun liner issues are among the most frequent causes of wire feeding problems. A liner that is cut too short is a common cause. The liner should stop inside the diffuser at the end of the gun neck. When the liner is cut too short, there is a gap where the wire can get caught inside the diffuser before it gets pushed through the contact tip, resulting in burnback or birdnesting.
When installing and trimming the liner, lay the gun flat and make sure the cable is straight and not twisted. Using a liner gauge can also help. Using the wrong size liner for the wire can also cause feeding issues. It’s recommended to use a liner that is slightly larger than the diameter of the wire to provide more room for the wire to feed through the liner. Because welding wire is coiled, it tends to corkscrew its way through the liner as it unspools. If the liner isn’t large enough, it takes more force to push the wire through. This can result in the wire breaking inside the gun or birdnesting at the feeder.
Liners are available in plated or non-plated styles, and the right choice depends on the geometry of the wire. It takes less force to feed wire through a plated liner because it has a smooth finish, while a non-plated liner has a rough finish. Therefore, it’s recommended to use a plated liner with cored wire because they are soft, and using too much force to push them through the liner could cause the wire to break.
A buildup of debris inside the liner can also lead to poor wire feeding. Debris can be the result of using the wrong type of drive rolls, which can cause wire shavings inside the liner, or it can be due to micro-arcing as the wire corkscrews through the liner. Over time, this micro-arcing can result in weld deposits inside the liner, which can require more force to push the wire through. Also, dragging the liner across the floor can cause it to pick up dirt and debris.
Replace the liner when buildup results in erratic wire feeding. Welding operators can also blow compressed air through the cable to remove dirt and debris each time the liner is changed.
Watch contact tips
Worn or dirty contact tips can cause wire feeding issues.
The hole at the end of the contact tip is large enough for the wire to feed through. Over time, the contact tip can wear and the hole becomes more oblong. This is called keyholing. In addition, small balls of spatter can sometimes become welded inside the contact tip, causing burnback and poor wire feeding.
Inspect the contact tips regularly for these issues and replace as necessary.
Sometimes in trying to address wire feeding issues, it also helps to go up or down a size in the contact tip. Try going down one size first, which can help promote better control of the arc and better wire feeding.
Lastly, the gun
If the other components and consumables have been inspected and adjusted as needed and wire feeding remains a problem, it may be that the wrong length of gun is being used.
Using a gun with a 25-ft. cable when one with a 10-ft. cable will suffice often results in bunching of the cable. The minute the operator starts coiling the cable during welding, wire feeding troubles can result.
Choose the proper gun length for the application and keep the cable as straight as possible during welding to help prevent wire feeding issues.
Wire feeding issues can cost time and money in downtime, wear and replacement of consumables and lost productivity. While there are many potential causes to poor wire feeding, many of them have simple solutions. It’s often a matter of methodically working through the checklist, starting at one end and working toward the other, to find the issue and implement a solution.