When it comes to the industrial use of lasers, most people are familiar with their application in operations such as laser cutting and additive manufacturing. However, there is a lot more that can be done by projecting a high-powered beam onto a base material.
There is, in fact, a wide range of things that could be done and all that’s changing is the power density and the interaction time required and sometimes the size of the laser beam, pointed out Steve Borle of Group Six Technologies, a dedicated laser processing shop based in Edmonton, Alta.
Borle focused on laser cladding for a presentation to the Canadian Welding Bureau’s recent virtual Welding Industry Day, a process he said he likes to think of as “additive manufacturing, just on a larger scale.” Borle compared laser cladding to conventional techniques and spoke about the advantages of making the switch.
Group Six Technologies uses lasers to do “preventative cladding” where they’re adding a corrosion protection layer to the base material. Often this is done, Borle explained, so a part can be made out of a less expensive base material with a more expensive alloy added on the surface where the part may be engaging with corrosive media or is subject to abrasion. Another area where there is a large demand for laser cladding is in repair and refurbishment with the aim being to extend the lifetime of expensive parts.
Borle began his presentation by explaining what is actually taking place when applying laser technology for a cladding operation:
“We are projecting a high-powered beam onto a base material. That high-powered beam is melting the base material and forming a weld pool. At the same that is occurring, we are feeding an alloy filler metal, as a powder or wire, into the weld pool,” he explained.
While that sounds straightforward, there is an important consideration concerning when it makes sense to use laser cladding rather than conventional cladding processes.
“It does tend to be more expensive than traditional processes such as stick welding and gas-shielded arc welding,” Borle acknowledges, adding: “It comes down to when heat input is a concern or when you want to decrease the number of machining steps.”
That concentrated beam of energy is exactly what gives laser cladding its advantage. It means a much higher power density than other welding processes, according to Borle. Laser cladding has the least heat input of any of the welding processes and the highest power density, he said. This decreases the amount of distortion in the part and there is a minimal amount of dilution compared to other processes. Laser cladding also provides the least dissolution of carbides.
“The other nice thing about laser cladding is that it’s very good when you need fine control of the weld area, especially when you’re using robotics. It’s only going to the very specific area. Once set up it’s very consistent, again and again. It does not have a spatter like you have with traditional processes when not set up properly. There is such a concentration of that beam energy compared to other processes that the power density is much higher,” Borle said.
Laser cladding combined with robotics makes for a particularly powerful combination. Group Six Technologies has four robotics cells, which allows the company to do ID and OD of parts. It can handle diameters up to 72” and up to 35-foot-long components. All the cells are self-contained with their own exhaust units. An operator will set them up and then essentially “hit a big green button” and things start running.
“We have a lot of emphasis on automation and one of the neatest things we have done lately is that we have taken highly automated and brought it to the full automation level. The handling of parts, pre-heating and measuring of parts before and after cladding are all done automatically,” Borle said.
In the company’s third cell, a robot is utilized to pick up parts and determine where to weld in space so that it welds in the right location for length and diameter.
“This is taking how welding automation is usually done and flipping it around. Usually with welding automation you are using the robot to move the welding head to the part and doing whatever work you need to do. In our case, for the third cell we are doing the opposite. We have the head stationary and do all the work with the robot,” Borle explained.
The other advantage robotics provides Group Six is allowing the company to handle some very complicated geometries and difficult parts. One basic example is vertical welding.
“Sometimes we have parts that aren’t symmetrical, and we can’t rotate them in the chuck, there is nowhere to grab on to them. We can actually place them on the ground and then weld them wherever we need to because we have so much access using the robots,” Borle said.