Most manufacturing operations are continuously looking for ways to improve productivity and throughput to gain a competitive edge. To achieve those goals, a greater priority is being placed on making processes as efficient as possible.
On a macro level, these efforts are happening industry wide. On the micro level, they’re taking place in almost every aspect and every department involved in the manufacturing landscape. And that includes the welding department.
Efficiencies can, of course, come in a variety of initiatives. In the right welding applications – such as those found in many heavy equipment manufacturing operations – a conversion from solid wire to metal-cored wire is a solution example that can deliver significant productivity and time-saving benefits.
To reap the advantages that metal-cored wire can provide, consider some key factors and best practices.
Metal-cored benefits
Traditionally, solid wire has been used for many of the welding applications common in heavy equipment manufacturing. Because of this history, many welders are familiar and comfortable with solid wire. It’s also seen as readily available and often considered a cost-effective option because it generally has a low cost per pound.
However, with the increasing emphasis on improving productivity and efficiency in the industry, more operations are looking to metal-cored wire to save time in the welding process. Depending on the application, the advantages of metal-cored wire can be wide ranging.
Metal-cored wire is formulated to provide specific benefits and properties, including reduced spatter during welding, a better bead profile and greater tolerance for dirty base material. Converting to metal-cored wire can provide benefits before, during and after welding.
First, metal-cored wire offers significantly higher deposition rates per given heat input compared to solid wire in many applications. This can result in increased travel speeds and reduced distortion on critical components, meaning manufacturers moving to metal-cored wire often achieve faster throughput with less rework.
Also, metal-cored wire tends to be more tolerant of dirt, mill scale and rust on the base material, so it doesn’t need to be as clean to produce high-quality welds. This saves time by eliminating or reducing non-value-added activities, such as cleaning, grinding and preparing the material prior to welding. Metal-cored wire is also typically more tolerant of gaps; this provides more flexibility because part fit-up may be less critical than it is with solid wire.
These advantages of metal-cored wire also help save time in the post-weld process. Because less spatter is typically produced with this type of wire, there is a reduced need for grinding and post-weld cleaning.
Some specific types of metal-cored wire are formulated to provide easier removal of silicon deposits or silicon islands on the surface of the weld, which also saves time in post-weld cleanup and grinding.
For the average semi-automatic welding operation, labor accounts for about 85 percent of the total costs. Any reduction in time spent on non-value-added activities helps make an operation more productive – and can have a substantial impact on the bottom line.
The ability to reduce or eliminate the time spent on certain tasks during the welding process – such as cleaning, applying anti-spatter, removing spatter and slag, and post-weld grinding – can provide significant productivity and efficiency benefits without adversely impacting the overall throughput or quality of the welding operation.
Filler metal options
Carbon and low-alloy steels are among the commonly welded materials in heavy equipment manufacturing. Metal-cored wire is flexible and works well with many of the welding applications in this market. Most metal-cored wire is well-suited for welding medium- to heavy-gauge plate and for lap welds, fillet welds, T-joints and groove welds, for example.
Common diameters of metal-cored wire are 0.045 in., 0.052 in. and 1/16 in. Often, switching from a solid wire to a metal-cored wire allows for an increase in wire diameter, such as from a 0.045-in. solid wire to a 0.052-in. metal-cored wire, while using similar welding parameters.
Because the heat input is typically lower with metal-cored wire, the process can handle a larger wire diameter and provide higher deposition rates. A larger diameter wire often means more material going into the weld joint, improving productivity to help get the job done faster.
For welding carbon steels, a common filler metal choice is AWS E70C-6M, which is a mild steel metal-cored wire. For higher strength materials, many types of low-alloy metal-cored wire are available to match the base material properties. With T1 steels, for example, a good choice may be an AWS E110C-K4, which is a high-performance filler metal that offers 110,000-psi tensile strength.
There are many options, and the right filler metal choice depends on the material being welded and the needs of the specific application. Once the filler metal has been identified, employing proper technique is also key.
The techniques for welding with metal-cored wire are comparable to the proper techniques for using solid wire. Torch angles and contact-tip-to-work distances are similar with both types of filler metals. This allows welders to learn metal-cored wire welding with minimal training.
Metal-cored wire provides more tolerance and a wider operating range than solid wire, so welders often find it easy to create high-quality welds. The penetration profile of metal-cored wire tends to be wider and provides a bit more flexibility compared to solid wire. From an operator standpoint, this means torch placement may not be as critical to achieving success with metal-cored wire.
A productive change
When considering a switch from solid wire to metal-cored wire, there are a few other factors to keep in mind to determine if it’s the right choice for a specific heavy equipment manufacturing application.
Metal-cored wire provides optimal results and productivity gains in longer, continuous welds that are in position. This wire is generally not as productive for applications involving many short welds with a lot of stopping and starting.
Like solid wire, metal-cored wire typically isn’t the most productive for applications that involve vertical and overhead welding. However, it can often be used for out-of-position welding with a short-circuit transfer mode or a pulsed process.
A lack of experience with metal-cored wire may lead to uncertainty in some operations about making the switch. But these filler metals are designed to offer ease of use, high deposition rates and a good bead profile with reduced spatter.
In welding applications that are well-suited for conversion, metal-cored wire can help significantly improve productivity and save time and money in the operation – while maintaining the high weld quality necessary in heavy equipment manufacturing.
Consult a local welding distributor or the filler metal manufacturer for answers to specific questions and help in determining if conversion to metal-cored wire is right for the application.
