A new method of laser beam induced surface modification using the Surfi-Sculpt^® process

Surfi-Sculpt^® is a power beam process, invented at and patented by TWI, which enables controlled surface features to be developed on a range of substrates, including but not limited to metals, polymers and ceramics. Such surface features were first demonstrated using electron beams, employing electromagnetic coils to first focus the beam and then deflect this focused beam over the material surface in a rapid and controlled manner. This paper will describe more recent work, which has involved the use of focused laser beams to develop similar features. Fibre delivered laser beams and galvanometer driven scanning mirrors have been used to produce the rapidly moving spot of laser energy required for the process. After generation of a molten pool in the substrate material, the beam is then rapidly moved relative to the work-piece. This, as a result of vapour pressure and surface tension effects, leads to material being moved from within the pool to regions at the extreme end of the beam movement. By repeating this process, it is possible to build up protrusions of several millimeters in height above the surface of the material. By combining and sequencing these protrusions together, a variety of shapes or features can be formed. The laser experiments have been performed in air and in various gaseous environments and, for comparison purposes, with electron beam work, in vacuum. The technique is not limited to the production of protruding surface features but can also be used to modify the structure deeper within the work-piece, so as to effect modification in the bulk substrate, for example, by way of the creation of deep holes in the material. The features created using the Surfi-Sculpt technique offer technical advantages and commercial opportunities in a wide range of industry sectors.