Cosmo Group is introducing cutting-edge new hand-held laser technology into South Africa that offers laser welding, cutting and cleaning capabilities from a modern and economical fibre-laser power source. African Fusion talks to Pieter Pistorius of the University of Pretoria about his interest in the system and to Petrus Pretorius of Cosmo Group about its core features and uses.
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”Our final year metallurgical engineering students at the University of Pretoria (UP) are required to do a classical practical at the end of their degrees, and every year we need to find novel welding-related research ideas. We typically use traditional processes to set up welding experiments, collect the data and then analyse the properties and metallurgy of the finished weld.
“This really began when we invested in a Lincoln Electric S350 Power Wave welding power supply for our SAIW Centre for Welding Engineering, which we purchased from Cosmo Industrial in Silverton a few years ago. We have since started attracting post-graduate students to do research in the welding field and produced several research papers,” Pieter Pistorius, tells African Fusion.
Cosmo, he adds, because it is both easily accessible and offers excellent support on the welding process side, has now become the UP Welding Centre’s go-to supplier of welding consumables and technical support. “We are not welders, so the Cosmo team has become very important to us. They know welding and we can have open discussions with them. When we show them a procedure, they will often ask why we want to do it like that? Then they simplify the welding to enable us to get far more practical and realistic results,” Pistorius says.
“We are currently involved in research at all levels into the solidification structure of thin ferritic stainless steel materials, using gas-tungsten (GTAW), gas metal (GMAW) and metal-cored (MCAW) arc welding,” he continues, adding that these steels are typically used for exhaust systems that get very hot. “We try to mimic the welding of exhaust-pipe tubing, for example, with a view to getting a finer grain structure into the weld metal that will be less susceptible to cracking,” Pistorius explains.
When Pistorius heard that Cosmo had set up a demonstration unit of a new hand-held laser welding system, he scheduled a visit to incorporate the process into the university’s research programme. “Petrus Pretorius did the welding for us in the demonstration centre at Cosmo. We see this process as an exciting addition to our research programme, as an alternative to GTA welding, for example. While the energy concentration of the beam is high, laser welding is known to offer reduced heat input compared with all traditional processes, which reduces distortion. For our research though, the lower heat input results in less grain growth and, potentially, finer grains with a less columnar and a more equiaxed structure in the weld metal.
“For the initial undergraduate project on this machine, the hand-held laser was used without (autogenous) and with filler metal using the machine’s built-in wire feeder, which seemed better. We haven’t yet got any definitive results, though, but we are definitely excited to have a new welding process to explore,” says the head of the SAIW Centre for Welding Engineering at the University of Pretoria.
Revolutionary hand-held solutions
Describing some of the revolutionary features of the hand-held laser welding systems, Petrus Pretorius starts with safety. “People need to be very careful when using any welding process, and hand-held lasers are no exception. Proper protective equipment is always necessary and the system does come with purpose designed laser goggles for eye protection,” Pretorius notes.
To avoid any possibility of the laser beam being accidently aimed at a person nearby, Cosmo’s hand-held lasers come with a safety-interlock, which automatedly turns off the laser power as soon as the gun breaks contact with the workpiece being welded. Pretorius explains: “Although it doesn’t really need it, the system will not work unless an earth lead is connected to the plate. In addition, the system is designed so the torch must be electrically connected to the workpiece before the laser can be activated,” Pretorius explains.
“The welding torch has a contact arm underneath it that the welder drags along the plate surface in front of the joint. The laser beam doing the welding will switch off the instant electrical contact between the arm on the torch and the workpiece is broken. This removes any risk of the beam being shone at anything apart from the metal plate being welded,” he adds.
The contact arm also makes welding easier than traditional TIG, MIG or MMA welding processes, in that there is no need for the welder to control the standoff distance between the torch and the workpiece. “The welding beam is very narrow, and while this is ideal for line-welding some autogenous joints on thin plate, the fit-up has to be very good. To ensure that no part of the joint is missed, the spot size of the laser can be increased or the beam weave function can be used. It also helps when wire is being fed into the joint at the same time,” says Cosmo Group’s Petrus Pretorius.
In terms of machine settings, he says there is nothing complicated to worry about. “As with all welding, the input power – set as a percentage laser power – is the main parameter, along with the wire feed rate. And as well as the spot size and weave functions, there are numerous other ‘fine’ settings such as sloping start and stop features.
“We are just beginning to get comfortable with the new process, though, and it will take time to learn how to weld most effectively with this system,” he adds.
The cost? “It is no more expensive than a high-end MIG/MAG or pulsed TIG system,” Pretorius responds, adding that hand held laser welding could result in many cost saving advantage. These include:
- The welding speeds can be many times faster than other processes, due to the highly concentrated laser energy source. This can significantly raise production efficiency.
- The low overall heat input from the concentrated beam makes lasers ideal for joining thin, delicate parts with much less heat distortion. “Fit up must be right, though,” Pretorius emphasises.
- Laser welds can be accurate with high quality and seldom need any post weld cleaning.
- The system is small and portable, so it can be moved from job to job inside a workshop.
- It is suitable for welding a wide range of different materials, including steels and stainless steels, aluminium, copper and many more.
- It can also be used to join dissimilar materials, providing a filler material compatible with both materials being welded can be found.
As well as the hand-held laser welding capability, the system can also do hand held laser cutting – for tube and plate – and hand held cleaning: “And these functions are activated simply by changing the torch nozzle and lens. “The laser cutting function can deliver good cut quality on any thin materials, while the cleaning function is ideal for cleaning rusted plate prior to welding, for example.
“This system is potentially revolutionary. It brings laser welding, which used to be reserved for highly specialised workshops and for welding very high-value components, into ordinary jobbing shops. For anyone looking to upgrade their welding operations or to expand what they can offer to South African customers, this 3-in-1 laser welding, cutting and cleaning machine might be an ideal solution,” Petrus Pretorius concludes.
