Poor wire feeding
Poor wire feeding is among the most common challenges that a MIG Welding operator deals with on a daily basis. Wire feeding issues can lead to increased downtime, premature wearing of consumables, and an overall weld quality that can be very poor in appearance and strength. There are several different issues that can lead to poor wire feeding. Although the most common assumption can be that the filler metal is the source of the problem, there are many other contributing factors that could also be the cause. Below are some of the most common causes of wire feeding issues in MIG welding.
Incorrect size or style of drive roll
Incorrect size or style of drive roll is one of the most common sources of poor wire feeding. The drive roll size needs to match the size of the welding wire being utilized. Using the correct style of drive roll is also a common problem. There are several different styles of drive rolls to match the wire being used for a particular type of MIG welding. A standard V-shaped drive roll is the best choice for solid MIG wires, while a knurled drive roll is the best choice for cored wires. U Groove drive rolls should be utilized for aluminum welding projects. Make sure to research the process and employ the correct drive rolls for specific welding projects.
Proper drive roll tension
Proper drive roll tension is also an important component of the MIG welding process necessary for smooth wire feeding. An excessive amount of drive roll pressure can cause the wire to be crushed and produce “flaking” of the wire which can contribute to the gun liner becoming clogged with the debris. It will also cause the wire to produce a “cast” (curling of the wire) which will lead to premature tip wear. Wire drive roll pressure that is too little can cause slippage of the wire so that it cannot be fed at the proper speed and can cause burn-back at the tip.
Worn wire guides
Worn wire guides can cause major wire feeding issues as well. A worn guide can cause the wire to bind up in the guide and may cause bird nesting in the wire feeder. It can also cause the drive rolls to slip on the wire due to the binding of the wire in the worn groove of the wire guide.
Worn or dirty MIG gun liners
Worn or dirty MIG gun liners are also one of the more common causes of wire feeding problems. Operators should check to ensure that the MIG gun liner is cut to the proper length. The MIG gun liner also needs to be the proper size and style for the weld wire used for a particular weld process. Using the wrong type or size of liner can lead to wire feeding issues. Operators should also check the MIG gun liners on a regular basis for the buildup of any dirt or debris inside the liner. A dirty or clogged liner can make feeding of the wire become very difficult and leads to several different welding issues like burn-back, excessive and premature consumable wearing and wire slippage in the drive rolls. Blowing out the MIG gun liner with shop air on a regular basis will extend the life of the liner and help to minimize wire feeding issues.
Contact tip and diffuser wear
The contact tip and diffuser can wear down and get dirty as they are used for the MIG welding process. As the contact tip wears, the tip will develop a key-hole wear pattern (the hole will become an oblong shape) and this leads to the wire loosing contact with the surface of the tip which causes conductivity issues and poor welds. The wearing of a tip will also cause small balls of spatter to fuse inside the contact tip over time, which can lead to burn back and poor wire feeding. Checking the tip should be one of the first things an operator should check if they are experiencing wire feeding issues.