Reduce Costly Downtime By Preventing Poor Wire Feeding
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 bird-nesting, burnback and 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 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, wire feeding issues often have simple solutions. 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.
Feeder, adapter and other equipment issues
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, this could be a feeder relay malfunction or a broken relay. Consult the 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 feeder, a poor adapter connection could also be the source of wire 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 an improper wire guide diameter can also 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 issues.
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 wire 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 for successful wire feeding.
Drive roll size: Drive roll size should match wire size — a .035-inch wire needs to be paired with .035-inch drive rolls.
Drive roll style: 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 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.
Drive roll tension: 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, leading to poor wire feeding.
Worn drive rolls: 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 bird-nesting in the 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 too much tension will cause the knurled teeth to dig into the wire and create shavings that can clog the 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
Liner issues are among the most frequent causes of wire feeding problems. Here are some things to check:
Liner length: A liner that is cut to an incorrect length can cause wire feeding issues, wire chatter, an erratic arc and/or burnbacks. Using a liner gauge can help when trimming the liner. There are also consumables that lock the liner in place (after loading it through the gun’s neck) at the front and back of the gun while concentrically aligning it to the contact tip and power pin. The liner is then trimmed flush with the power pin at the back of the gun. There is no need to measure. This type of system provides a flawless wire-feeding path.
Liner size: 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 bird-nesting at the feeder.
Liner style: Liners are available in plated or non-plated styles, and the right choice depends on the geometry of the wire. A plated liner has a smooth finish, while a non-plated liner has a rough finish. It takes less force to feed wire through a smooth, plated liner. Therefore, it’s recommended to use a plated liner with cored wires since they are softer, and using too much force to push them through the liner could cause them to break.
Liner buildup: 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 roll, which can cause wire shavings inside the liner, or it can be due to microarcing as the wire corkscrews through the liner. Over time, this microarcing 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 for contact tip wear
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. With use over time, the contact tip can wear and the hole becomes more oblong in shape. This is called keyholing. In addition, small balls of spatter can sometimes become welded inside the contact tip, causing burnback and poor feeding of the wire.
To minimize the opportunity for keyholing, look for a consumable system that concentrically aligns the liner and contact tip, since this connection creates less mechanical wear on the tip’s interior diameter and reduces the risk of keyholing. Less keyholing also means less chance of an erratic arc, excessive spatter or burnback, which helps lengthen the life of the contact tip. These systems also bury the contact tip further in the gas diffuser to protect it from heat damage. Shielding gas cools the contact tip tail as it flows through the gun, further reducing heat and minimizing contact tip wear.
For all consumable systems, inspect the contact tips regularly and replace as necessary.
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-foot cable when one with a 10-foot cable would suffice often results in bunching of the cable. The minute the operator starts coiling the weld 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 feeding issues.
Troubleshooting 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.
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