Full factorial experimental design was used to investigate which factors were believed to affect the laser percussion drilling process. Once the relevant factors had been identified and also which factors interact, other techniques are needed to find the exact settings for each of the factors. If the factors in question affect the response variable in a linear fashion then the Taguchi method for optimisation can be employed to find the correct levels for each of the factors. If however the factors affecting the response vary in a non-linear way or they interact with each other then another method is needed to optimise the drilling process.
An experimental method that lends itself very well to this task is Response Surface Methodology (RSM). RSM consists of a group of techniques, which are used, in the empirical study of the relationship between one or more response variables such as hole taper, hole roundness and hole variance. RSM is a natural progression from the experimental design used in the initial investigation. RSM attempts to build a surface, which shows the optimum settings to produce a maximum or minimum in the relevant response variable. These processing maps can be overlaid for the various response variables to produce an operating window. The work presented is based on results of work previously reported at ICALEO 1998 and reported by French (1), due to space available only the data for hole taper will be presented in this paper.