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In the process of machining free-form surfaces, the surfaces
are often sculptured by a three-axis CNC machine with a
ball-end mill cutter. After machining, improvement on the
surface roughness becomes a considerable important
problem because the surface roughness affects the performance
and appearance of the products. In this study, experimental
factors, including cutting speed, feed, axial depth of
cut, inclination of specimen and tool radius, are taken into
consideration to investigate the effects of on the surface
roughness. To do this, the experimental design is adopted to
model the relationship between cutting conditions and surface
roughness. In the experimental design, the matrix is
planed by means of Response Surface Methodology and
Taguchi Method. The results associated with the
analysis of the variance can be practiced to assess the
prominence among experimental factors. The analysis
indicates that cutting speed, feed and tool radius play
significant factors on surface roughness. The results of
the regression analysis using a statistical software can be
applied to model the mathematical relationship between
machining factors and surface roughness. It
anticipates that the model is able to predict surface
roughness over a wide variety of cutting conditions. The model
is also proved in good agreement with experimental
results. Finally, an optimum method is adopted to search
the optimal cutting conditions with a better surface
quality under a wide variety of the tool radii and inclinations
of the specimen.
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