In Aluminium Welding, it All Comes Down to ControlProperly Equipped and Programmed
The right combination of consumable chemistry, process capabilities and equipment spell success for welding on popular substrate in trailer manufacturing setting
by Frank Armao, Director of Aluminium Technology, The Lincoln Electric Company
Trailer manufacturing is one particular industry where the proper union of these variables comes into crucial play. Manufacturers in this segment use aluminium quite commonly and, thus, require welding solutions that deliver strong, attractive welds quickly and efficiently. These manufacturers are seeking fast travel speeds, clean welds and consistent bead profiles every time.
At the recently constructed Great Dane Trailers refrigerated trailer manufacturing facility, which opened in April 2012 in Statesboro, GA., company executives sought to install the latest technology, including welding equipment. Consistent material flow and throughput is a constant goal at the plant – and this holds true in the welding booths, as well.
“When we put in new welding equipment, we wanted consistency to be our first priority,” notes plant manager Kevin Black. “And, if in the process, this equipment upgrade makes us a little more efficient, then that’s even better.”
Great Dane’s fabrication crew uses advanced process Power Wave® welders from Lincoln Electric with pulse waveform technology for automated welding on the refrigerated trailers’ aluminium floors – a complex process that involves a continuous, 53-foot seam weld of 12-inch boards across the entire trailer floor. The system features 10 boom-mounted wire feeders and fixed torches on a hard automation, mechanical gantry that rides up and down the floor on rails.
Exploring Waveform Technology
Pulse waveforms typically deliver better penetration with lower heat at faster travel speeds, providing a stable and consistent arc with fewer defects. Through the instantaneous feedback from the power source, the automated system responds more quickly to stickout changes and contamination in the weld.
Over the years, improvements in waveform control technology have helped operators gain extremely fast arc response and optimized performance in almost any application. Welding equipment manufacturers have sped up the waveform technology to boost efficiency and weld consistency. In the past, inverters might have operated at 40, 60 or even 80 kHz, but the waveform control was only 10 kHz, so it only “made decisions” controlling the weld at that speed – sacrificing a machine’s full power for the sake of accurate waveform control.
Today, both the waveform control and the latest inverters operate at 120 kHz, with waveform capable of changing up to every 8.3 microseconds. Parts of the waveform can be independently manipulated, including peak on time, peak current, background and current and pulse frequency. These are synergistically controlled when an operator picks a wire feed speed, or selects the nominal waveform for the given wire and welds. If there are job-specific parameters, these can be included in the setup.
This controllability makes a big difference, allowing modern advanced process welding power sources to react much faster to a higher level of detail and regulate the process with more precision, including both wire feed and travel speeds. Operators have the ability to maintain better control of the arc, which can adapt not only to gaps but also material and joint variations.
In automated systems, such as that used at Great Dane, welds can be made faster without inconsistencies and loss of puddle control, eliminating spatter, lack of fusion and undercut, while avoiding discontinuities in the weld and reduced quality. With the delicate nature of aluminium substrates, this is even more important for achieving quality welds and consistent throughput.
Consumables, Chemistry Control and Quality
The success of the latest welding power source and waveform technology, however, also depends on the type of consumable specified for the job, particularly in aluminium trailer fabrication – and on trailer floors because they are a highly visible feature.
“You want your floor to be sealed tightly and not have any issues with moisture infiltration, which could comprise the integrity of the floor and the insulation underneath it,” notes Great Dane’s Black. “You want to be sure you have good coverage on your floor. You can achieve this with a material that not only bonds as it should, but that is easy for the operators and welding equipment to deliver a nice, smooth appearance. You want the floor’s cosmetic qualities to go hand-in-hand with the structural qualities.”
Welders at Great Dane selected a consumable specifically designed for the trailer manufacturing industry – in this case, Lincoln Electric’s SuperGlaze® 5356TM GMAW (MIG) welding wire with chemistry developed by Indalco Alloys®, a division of Lincoln Electric.
This particular engineered aluminium alloy GMAW wire was designed to provide optimal puddle clarity and arc action, as well as excellent wetting for both semi-automatic and high productivity automatic applications. Additionally, its proprietary formula and strict chemistry control contribute to a consistent bead profile and appearance for a smooth surface finish at high travel speeds.
Chemistry control supports such factors as a consumable’s mechanical properties, flow, operability and more. Strict oversight of this chemistry throughout the manufacturing process can help to eliminate troublesome variations and ensures consistent, reliable performance, even on the most temperamental substrates – including aluminium.
Chemistry control also equals quality; quality – more often than not – equals certifications. When choosing the right consumable for any application, it’s also a good idea to review each product’s specific certifications. Look for products certified to meet AWS minimums, however, note that some manufacturers are capable of providing mechanical properties beyond AWS minimum without sacrificing operability advantages.