Spray welding is a thermal spraying process where material is melted and sprayed onto a surface to form a new layer.
At its core, spray welding involves a wire or powder feedstock is melted by a flame or plasma torch and sprayed onto a prepared surface, forming a coating or build-up layer. This technique allows for the application of a new surface layer to existing components.
The Spray Welding Process Explained
The process can be broken down into a few key steps:
- Surface Preparation: The part receiving the spray weld is typically cleaned and prepared. This might involve degreasing, grit blasting, or machining to ensure the sprayed material adheres properly.
- Feedstock Melting: A wire or powder feedstock material is introduced into a heat source. This source is often a flame or plasma torch, which generates enough heat to melt the feedstock material. The choice of feedstock (wire or powder) and the heating method depend on the specific material being applied and the desired outcome.
- Material Spraying: The molten or semi-molten feedstock material is propelled towards the prepared surface. This is usually done using a stream of compressed gas.
- Layer Formation: As the hot particles strike the surface, they flatten and cool rapidly, bonding to the substrate and to each other. Successive passes build up the desired coating or build-up layer.
Why Use Spray Welding?
Spray welding is a versatile process primarily used for two main purposes, as highlighted by its applications:
- Repair and Restoration: It often repairs worn or damaged parts. Instead of replacing an entire component, a worn area can be built back up to its original dimensions and properties. This is common for shafts, bearings, and other mechanical parts subjected to wear.
- Protective Coatings: The process also applies a protective coating to a surface. This coating can provide resistance against wear, corrosion, heat, or other environmental factors, extending the lifespan and improving the performance of the underlying component.
By applying a new layer of material, spray welding offers a way to enhance or restore the surface properties of components without significantly affecting their bulk properties.
