Over time, science has guided best practices for the welding process. It works to reduce waste, increase profitability and build better bonds. In other words, these studies have delivered an understanding of which metals and materials work better with less waste and more efficiency.
Science, however, continues to move forward, meaning that new best practices are constantly being discovered. Therefore, for any company that welds on a regular basis, the importance of making smart decisions based on scientific studies, personal experience and industry know-how cannot be stressed enough.
Common practice
Many fabrication shops that specialize in architectural systems and components make their products out of aluminum, which is chosen for its strength, durability and versatility. Stainless steel and carbon steel are also utilized, depending on the needs of the project. However, aluminum is growing in popularity across the industry as it is being used more and more as an alternative to steel.
For components used in architectural aesthetics, aluminum is ideal. In these applications, aluminum is preferred because of its appearance, its resilience to corrosion and its light weight. Its material properties also make aluminum easy and fast to form and machine.
Understandably, there are compromises made with any material decision. When choosing aluminum, strength comes into question, depending on the type of structure being fabricated and what it will ultimately be used for. The risk of denting and scratching is also higher due to its malleability. This makes it more prone to damage than steel and some other metals. Because of this vulnerability, aluminum requires more of a “white glove” approach.
Decisions on which material to use are engineered to project specifications. Often, the decision-making process is based on the experience a team has with certain materials. The higher the level of experience, the better the outcome and the better prepared they are to overcome any potential issues in the future.
Science of selection
Every project, regardless of its size, begins with a plan. When creating this plan, choosing the best filler metal cannot and should not be low on the list of priorities. This decision must be based on the alloy elemental composition and any possible reactions to the base metal.
When working with aluminum, the choice of filler metal may be more complex because of the multiple types of aluminum in the marketplace. Fortunately, there are designations based on the multiple variations from which to work off of. These groups are based on the characteristics of the metal and are called “series” to help differentiate one from another. At many fabrication shops, the most common type of aluminum used is the 6000 series. This particular type is used for its ability to be extruded with different temperature designations.
The groups or series are based on a four-digit number system, which could range from 1000 to 8000. The first digit indicates how pure the aluminum is, ranging from 1 to 8, with 1 specifying 99.99 percent purity. The second digit indicates there has been a special modification to the aluminum. The last two digits label the specific alloys that have been added with a numerical breakdown for the possible additions that could be made.
Additionally, there will be a letter ‘T’ if the metal has been tempered, and the digit following indicates if the metal has been heat treated in a solution and artificially aged. There are various numbering combinations for almost any type of metal composition and treatment. The 6000 series that some shops use has coding that notes how magnesium and silicon alloys are added to the aluminum.
Common types of filler metals used include 5653 for aluminum, 308L for stainless steel and ER70S-6 for carbon steel. Another popular filler metal for many welding and fabricating shops is 4043 aluminum. Various types of filler metal become popular simply because of their ability to meet the needs of the product, but the ultimate choice often lies in finding the intersection between cost-effectiveness and quality – securing the best possible product at the lowest cost. Depending on the base alloy being welded, there are a few types of filler metals from which to choose. Each carries with it a certain set of ramifications.
Every new project, therefore, requires deep research to make the best choice. The proper filler metal affects how strong the weld is and determines the end product’s structural integrity. Choosing the wrong metal could weaken the entire system, causing lateral failure and corrosion. Familiarity with the metals used is critical.
For example, experienced welders that understand the characteristics of 6000 series aluminum know the value of 5356 filler metal and that the match is based on its resistance to cracking as well as its excellent ductility and higher than average corrosion resistance. These welders also know that it is aesthetically favorable because of its color-matching quality. This creates a seamless look after anodization. As the field progresses, there are certain changes that occur to help increase the productivity and reduce the waste.
What might seem like an incredibly complex aspect to a new project – given the seemingly unlimited number of filler metal/base metal combinations – there are several ways to choose the best filler metal for the job. First and foremost, it’s key to talk to the welders and welding supervisors assigned to the job, but it can also be fruitful to ask the filler metal manufacturer or distributor for help, as they can dip into their wide base of experience for answers.
Changes in technique
Depending on the project, filler metals might not even be required. In fact, innovations to today’s welding practices are becoming quite popular with companies that want to reduce waste. One such technique is friction stir welding (FSW), which was invented in 1991 by Wayne Thomas at The Welding Institute in Cambridge, England. FSW doesn’t require any filler metal, which can be a huge benefit to companies when it comes to budget management. Filler metals can become expensive depending on the grade of alloy needed for the project, leading FSW to become a cost-effective alternative for certain manufacturing companies.
FSW works by using a machine with a rotor-driven chuck that tightens onto one half of the material to be welded, while the other half remains stationary. One end of the chuck rotates, and pressure is forced onto the two workpieces creating heat at the weld interface up to 1,300 degrees F. FSW is also eco-friendly as it does not release any toxic fumes into the environment.
Many modern manufacturers have turned to FSW in today’s market of Earth-friendly manufacturing as it helps to replicate a single process uniformly over and over again. A popular application is for processing smaller, scheduled pipe. However, it’s important to understand that FSW isn’t always well-suited for custom fabricators as the equipment can be fairly expensive and very few projects require multiple identical pieces.
New in the field
Even if a fabricator can take advantage of FSW, there will still be a need for filler metals. And as time passes, the industry will continue to find ways to reduce the amount of metal needed, search for better combinations of welding gases, and improve processes and tools.
In addition to filler metals, other consumables, such as welding gases are undergoing research and advancements. For example, a recently optimized welding gas blend called Stargon AL, used primarily for aluminum MIG and TIG, works to improve welding performance and travel speeds. It is said to be a carefully prepared proprietary blend of argon with precisely controlled parts per million additions of active gases. The weld doesn’t require as much cleaning afterward.
Other advancements may also be made to increase how machining can be involved in the welding process, giving the ability of streamlining and automating the welding process. The field is expected to see continued refining of the process, finding better ways to match the right metals, gases and welding processes.
Because of the ever-changing, ever-improving world of consumables and filler metals, it is always recommended to work closely with the manufacturer or distributor when choosing new products for new projects. It may also be beneficial to consult with those trusted companies to discover whether there are new products to replace long-running standbys.
