Rapid prototyping by laser surface cladding
In recent years rapid prototyping technology has been implemented in many spheres of industry,
particularly the field of product development. Existing process provide the capability to rapidly
produce a tangible solid part, directly from three dimensional CAD data, from a range of nonmetallic
materials. In many situations the desired end product of a development cycle is a
metallic object, whether a component or a tool. The development of a system capable of the
direct manufacture of fully dense, metal parts is therefore seen as an important landmark in the
evolution of rapid prototyping technology.
A unique experimental project has been carried out to investigate the potential of laser
surface cladding by pneumatic powder delivery to form the basis for such a process. A layered
manufacturing part building strategy is proposed, in which laser cladding is used to deposit the
near net shape of each layer. Conventional machining techniques are then used to trim each layer
to the exact dimensions specified by the CAD data. A multi-kilowatt carbon dioxide laser was
integrated with a four axis machine tool to create an opto-mechanical workstation on which to
perform the process.
A detailed study of the effects of cladding process parameters on the geometry of the
deposited metal was carried out and quantitative relationships derived. These relationships are
used to select process parameters appropriate to the geometry of the deposition required. A
numerical method to fully describe the deposited clad geometry was developed in order that
efficient cutter paths could be generated for the back machining cycle. These relationships are
also used to determine the minimum size of deposited bead from which the required layer section
may be machined, in order to optimise process efficiency.
The application of the technique to the generation of a variety of simple geometries was
investigated and the potential problems identified. A preliminary investigation into the process
accuracy is made, relating specifically to the predictability of the geometry of multiple layer
depositions and the distortion of parts as subsequent layers are deposited.
The limits of geometrical complexity possible with the current apparatus, and the
unsatisfactory build times involved, suggest that the most attractive application of this technique
is as part of a hybrid process, adding a novel additive dimension to existing automated