Laser cladding creates a metalurgical bond between the base material and the overlay, ensuring nothing can penetrate.
Edmonton’s Group Six Technologies employs laser cladding to increase the durability of mechanical parts
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.
Laser cladding is one such application and it can be an effective way to increase the durability of mechanical parts, points out Steve Borle, materials/welding engineer with Group Six Technologies. Heavy industry would seem to agree as the dedicated laser processing shop based in Edmonton, Alta., has enjoyed strong growth since starting operations in 2013 in a 12,000 sq ft facility.
Group Six Technologies uses Coherent Inc. and Laserline lasers to do preventative cladding, adding a corrosion protection layer to the base material on industrial equipment. Often this is done so a part can be made from a less expensive base material, such as steel, with a more expensive corrosion resistant alloy added on the surface where the part may be engaging with corrosive media or is subject to abrasion. Another area where there is large demand for laser cladding is in repair and refurbishment with the aim being to extend the lifetime of expensive parts. Group Six Technologies has employed laser cladding to restore components such as shafts, housings, blowers, and spindles back to original shape and size. Bearing fits can be brought back to size so that mating parts don’t have to be tracked for oversized/undersized configurations and seal areas can be built back to nominal size as laser cladding allows thicker layers than the use of chrome.
Borle, who has been with Group Six Technologies almost since the company’s inception, says he likes to think of laser cladding as “additive manufacturing, just on a larger scale.”
“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 time that is occurring, we are feeding an alloy filler metal, as a powder or wire, into the weld pool,” he explains.
When compared to other methods of overlaying material, laser cladding provides several advantages, according to Group Six Technologies.
Laser cladding creates a metallurgical bond between the base material and the overlay so, unlike the use of chrome or HVOF, nothing can penetrate through the overlay and corrode the underlying material.
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.”
Laser cladding requires very low total heat input, which results in a narrow heat affected zone and allows for virtually no distortion of tight tolerance components. It also creates a relatively smooth surface with little or no porosity.
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 says.
“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 emphasizes.
Laser cladding combined with robotics makes for a particularly powerful combination. Group Six Technologies has three Fanuc-powered robotics cells. With six-axis robots and two-axis positioners, parts of any shape and size can be clad. Internal cladding heads can reach into deep bores down to 60 mm (2 3/8 in.) 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 says.
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 explains.
The other advantage robotics provides 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 says.
Group Six Technologies takes pride in being laser focused, pun intended, on laser materials processing. The company has deliberately chosen not to offer machining services, spending all its energy and expertise on improving laser cladding, laser hardening and laser welding. (It does offer its own grinding services and has partnerships with several companies to provide machining as part of a turnkey solution when required).
The company’s customer base is across Canada and the U.S. but it has plans to reach out to customers overseas with its fourth cell, which will be a mobile laser, by the end of this year.
“That is a really big deal for us because it should open up a lot of different areas and there are a lot of companies which need mobile service,” Borle says. Good examples where a mobile laser cladding service would be needed include large parts, such as giant turbines, where it’s either too expensive or just not possible to move them for repairs, or cases where it would be much more expensive to ship a large pile of parts for repairs than to have a mobile laser cladding service come in and handle the repairs onsite.
“We would be willing to go overseas with this service,” Borle says. “We’ve been looking at offering the mobile option in South and Central America because there is definitely a need for it but not many providers.” SMT