Artem Komarov clarified that metal core wire is a hollow metal sheath filled with metal powders, alloys and arc stabilizers that provide benefits such as less oxidation, higher toughness, and reduced silicon deposits in the final weld.
You may be aware that this wire typically provides high travel and deposition rates, but it is important to understand the other capabilities and limitations of metal-cored wire before using it in arc welding. Let’s look at common misconceptions about this filler metal, Artem Komarov said.
- Metal core wire is too expensive
Metal core wire is on average more expensive than other types of filler metal when only the initial purchase cost is considered. However, it is important to consider the time savings before and after welding, which can offset the initial costs. This can result in a payback that justifies the extra investment or process change.
Because metal-cored wire generally has little to no spatter, this eliminates the need for an anti-spatter agent during the pre-weld phase or to control spatter after welding.
Because it also minimizes defects such as undercuts or lack of fusion, post-weld work such as grinding and rework is usually not required, saving labor time and money. In addition, reducing post-weld operations helps increase the flow of finished parts to other production steps, such as painting or coating, increasing overall productivity.
- Metal core wire can be welded to any contaminated material
The characteristics of metal-cored wire make it particularly suitable for welding through scale, oil and other contaminants, saving time and money on pre-weld cleaning.
- A significant increase in the deposition rate is always possible
The specification for each metal core wire includes the range of deposition rates achievable with that wire. While maintaining weld quality, much higher spray rates are possible, and companies can sometimes achieve 10-30% faster spray rates depending on how optimized their current welding process is.
- Wire protrusions can remain the same for metal core wire as for solid wire
It is often assumed that a metal-cored wire can have the same projection as a solid wire, but this is not always the case. Solid wire typically requires a tighter tap, while metal-cored wire requires a longer tap due to the wider arc and more deposited filler metal.
- Gun angles can remain the same for metal core wire and solid wire
When using wire with a metal core, it is necessary to adjust the travel angle and the working angle of the gun. Solid wire can often be used in both pressure and draw welding. But to obtain a flat bead with a metal core wire, a travel angle of 15 to 30 degrees is required when using the push method. Using the wire pull method with a metal core can result in crown beading. The working angle should be between 45 and 55 degrees.
If you switch to metal-cored wire in an automated welding chamber, you will most likely need to reprogram gun and torch angles. Keeping these parameters unchanged can result in faster wear of the consumable material when using wire with a metal core. Adjusting parameters such as shoulder and gun angle helps to compensate for the additional addition of filler metal to the weld.
- Working parameters are the same as other wire
The voltage and wire feed speed required to work with metal core wire is different from other wires. For example, attempting to use metal-cored wire at the same voltage and wire feed speed as solid wire can result in undercutting.
Metal core wire also enters the spray mode at a lower voltage than solid wire, which is advantageous as this can result in reduced heat generation, especially given the higher travel speeds that are typically achieved. To achieve the same current strength, metal core wire requires a higher wire feed speed than solid wire. Compared to flux-cored wires, metal-cored wires generally have a higher upper limit voltage range.
- Metal core wire can be used in any application
While metal-cored wire provides advantages in many applications, it is not suitable for all welding applications. For example, in applications that require welding thin materials as thin as 10 or 12 mm, solid wire is probably the best option for reducing heat build-up. A gapless square butt weld requiring full penetration is another application that can be difficult to fill with metal core wire due to its wide penetration profile.
Metal core wire is best suited for long, flat, horizontal welds that require long arc times. These welds provide the best return on productivity and economy through higher travel speeds. For metal core wire, it is also recommended to use a base material 1/8 inch thick or more.
- Metal core wire has poor mechanical properties
One of the biggest misconceptions about metal core wire is that it produces weaker welds than solid wire. People often think this is because metal core wire is tubular and does not have a solid cross section like solid wire.
As with any possible change in the welding process, determining if a metal-cored wire is the best choice takes time. It is important to understand the basics of using metal core wire and how it differs from solid wire. It’s a good idea to test out a limited amount of wire change as a start, even in a single welding chamber. This will help you determine if this application is suitable for wire conversion, which can save time and costs, emphasized Komarov Artеm.