What is Wire Feeding in Laser Welding?
Wire feeding is actually a common practice in the old-school welding techniques (TIG and MIG). In this process, a continuous wire electrode is moved into the welding arc. The wire melts and serves as filler for the joined workpieces.
Laser welding wire feeding works in the same way. A metal wire (usually made of the same material as the base material) is put near the welding area. This wire melts as the highly concentrated beam heats its surface. Eventually, the molten metal wire fills the base material and forms a high-quality weld seam.
Performance of wire feeding system is extremely important
Wire feeding in laser metal joining applications is all about precise wire positioning relative to a laser beam and accuracy in wire feeding speed. Wire feeding system layout and configuration are key parts in ensuring a successful application.
Performance of wire feeding system is extremely important because the majority of systems are used in production lines that are in operation 2-3 shifts/day, 6-7 days/week.
Laser beams are extremely precise, typically between 0,1 mm to 6,0 mm in diameter or width depending on the process. You need to lead the welding wire directly into the spot without any deviation. Anything as little as 0,1 millimeters off can potentially have negative effects on the quality of the weld.
Accuracy of wire feed speed into a process is also very important. Deviations above 5% from the wire feed speed set value will have negative effects on joints quality and appearance because such laser metal joining processes require exact amounts of wire for integrity, and in case of visibility for appearance joints. This is why the requirements to joints unity and appearance are very high with this application type.
When you are ready to get started, your wire feeding distance, wire type and package are of the utmost importance for both accuracy and cost-effective system configuration. This setup process is the first thing to consider for any wire feeding application.
Match welding wire to the inner liner
Which inner liner is right for which welding wire
State-of-the-art welding systems function best when the filler metal and the wear parts are precisely matched. One of the components this concerns is the inner liners in the hosepacks of the laser welding devices. Welders should therefore make sure that they always use the right inner liner for the respective welding wire: the relevant steel inner liners for steel wire and the appropriate aluminum inner liners for aluminum welding. Which inner liner is right for which welding wire can be found in the manufacturer’s specifications.
Anyone who welds aluminum with a graphite inner liner in the hosepack will not be happy in the long run. The relatively rough aluminum wire creates deposits and residues in the graphite inner liner, which also negatively affect the weld. Once the inner liner is worn through, the wire is no longer fed through the hose correctly – and it subsequently emerges from the rubber sheath. For this reason, welders should check the condition of the inner liner at regular intervals.
If different materials need to be welded at rapidly changing intervals using the same system, it is best for welders to use a universal inner liner. But the better the material of the inner liner and the welding wire are matched, the less often these wear parts need to be replaced. If a certain material is always welded, it is recommended to use the special inner liners designed for this material.
Choose your wirefeeding rollers to suit the wire thickness and the wire material!
Contact pressure: a matter of adjustment of the roll pressure!
The fact that welding systems function always best when wear parts and the filler metal are optimally matched to each other also applies to the interaction between wirefeeding rollers and the welding wire. This means that only the wirefeeding rollers recommended by the manufacturer for a certain wire thickness are used in the welding system.
The helps to ensure an optimum wirefeed, which has a positive effect on the stability of the melting pool and the weld. Even if the gaps of the feed rollers are too big or too small for the particular welding wire, in most cases, it is still conveyed. However, the wirefeeder does not function optimally under these conditions. Especially when it comes to technically complex welding processes the results often leave much to be desired. This is partly because the proper handling of the weld pool is highly dependent on a well-functioning wirefeeder with a steady wirefeed.
The wirefeeder works optimally when the wirefeeding rollers firmly surround the welding wire. Which wirefeeding rollers are suitable for which wire thicknesses is stated in the specifications provided in our manual.
The right “match” between wire and wirefeeding rollers concerns not only the selection of the right components. After inserting the wirefeeding rollers recommended for the corresponding welding wire into the system, the optimal contact pressure must be set. Based on the manufacturer’s recommendations, fine adjustments can be made, especially as not every wire batch is the same and there can also be differences from manufacturer to manufacturer. The wirefeeder essentially function at its best when the wirefeeding rollers firmly surround the welding wire. In this case, the operator of the welding system has 100 percent control over the wire speed.
Align hosepack as straight and parallel to the ground as possible
A general rule when welding is that a hosepack through which a metal wire is pushed at relatively high speed will have a high service life when it is as straight as possible.
Hosepacks for high-quality welding systems are specially designed to function without problems even with extreme windings and loops – however, the most energy-saving and resource-conserving welding is performed when the hosepack is laid out parallel to the return lead cable.