Robotics Tech Papers
Robotic Laser Cladding
Wolf Robotics, A Lincoln Electric Company Posted 05/27/2014Additive Manufacturing using Additivie Shaping
Advancements in laser technology over the past decade have been improving at an exciting rate. Companies interested in traditional welding have been adopting the technology and are leading the movement towards laser welding additive manufacturing processes. Of particular interest is the integration of laser cladding cells for mining, construction and agricultural applications.
Laser Cladding is a form of Additive Manufacturing that fuses together successive layers of additional raw materials to a base material. The additive shaping can be accomplished by two similar but separate techniques.
- Use a powdered metallic substance that is injected into the laser beam causing it to melt and adhere to the surface of the substrate.
- Feed a heated solid wire, similar to welding, that the laser beam melts to the base material.
These two processes allow the repair of worn out parts while increasing and/or improving mechanical properties and corrosion resistance. Utilizing the coordinated motion of the robot and positioner it is possible to build up the outer diameter of a spindle shaft that is no longer in tolerance. The resulting surface is then remanufactured by grinding to the proper dimensions and the part is restored to a serviceable condition. Often the finished surface is better than the original, due to the improved metallurgy components.
The powder process offers an array of exotic elements and the opportunity to bond them with an assortment of different materials typically in layers 20 micrometers thick. The wire process is more restrictive in material but it offers a much higher deposition rate capability.
Laser Cladding is being used in applications in the construction industry to repair and reclaim components (i.e. worn wheel spindles of large mining trucks). In agriculture, laser cladding is being used to harden and overlay different surfaces on assorted equipment (i.e. combines, augers, etc.). One example is cladding the tips of corn choppers to impart enhanced metallurgical properties to new equipment.
Companies are finding that robotic laser cladding can actually restore and improve the physical integrity of wheel spindles up to 8,000 kg, which is typical of multi-ton mining trucks, at a lower cost than purchasing new components.
Integrating robotics allows for other advanced technologies to be utilized in laser cladding cells. Many of the process parameters must be continually monitored, such as laser power, laser focal point, powder injection rate, etc. HMI (human machine interface) allows the customer to change the process as its happening. A parametric program then allows you to automatically set how far you want to clad the part and the diameter of what you’re cladding. Therefore there is little programming involved for unique parts. Human machine interface also allows you to display the laser parameters and have special parameters for different parts. You can also incorporate vision capabilities and error handling so a technician isn’t required to monitor the process. A laser spot camera is used to ensure that when non-uniform parts are detected, the laser sensor will adjust for the offset.
- Extends part lifetime
- Strong metallurgical bond
- Increased corrosion resistance
- Minimal heat affected zone
- Reduced substrate deformation
- Free of cracks and porosity
Importance of Safety
When working with lasers safety is of the upmost importance. It is crucial that safety be established in every laser cladding system. Complete containment enclosures around the robots is required, since no light can escape, it can actually be classified different if not completely shielded. Laser Additive Manufacturing While robotic laser cladding is gaining a stronghold in many applications, the recent advances in fiber-delivered solid-state lasers and their decreasing ownership costs are moving other laser welding processes into the mainstream. Wherever lasers take welding in the years to come, robots will be there as technology enablers and trusted partners in the campaign.