Analysis and Synthesis of Engineering Surfaces in Bridge Manufacturing and Design - Manufacturing Systems Processes - page 36

FIGURE 1.17 Surface analysis of Part #1.

FIGURE 1.18 Surface analysis of Part #2.

To demonstrate these goals, we first investigate surfaces of parts built using a polycarbonate powder
[68]. The surface profile of such a part is shown in Fig. 1.17 . These surfaces indicate a rough structure,
which the designers would like to eliminate. The rough structure is a consequence of the material choice,
and is unacceptable for customer satisfaction. Additional finishing processes typically follow part produc-
tion to eliminate this problem. Analysis of these surface profiles using the Karhunen-Loève transform
reveals a predominantly stochastic structure, without any coherent structures revealed. However, the
roughness of the surfaces is in the order of 30 m, which is the same order of magnitude as the particle
diameter of the powder used to build this part. This information is passed onto the designers. The designer's
recommendation is to change the powder type and particle size to remedy the problem.
Figure 1.18 s hows a part produced using a powder with smaller particle size. The corresponding surface
profile shows an improvement over the previous part profile. In fact, the surface roughness has been
reduced to an average value of 10 m, and the part surface is no longer rough to touch. The improvement
on the surface roughness is satisfactory to the designer and the customer. However, as a consequence of
the first remedial action, new fault patterns are revealed on the new part surfaces. We first use a standard