View/Open - Scholarly Commons Home

have many factors from contention and find those important few factors that do
contribute to a product problem or contribute to product quality improvement.
Cause effect diagram
The structure for a cause effect diagram begins with the basic effect that is produced
and progresses to what causes there may be for this effect. Primary, secondary and
tertiary causes are branched off the main trunk of the “effect” tree. Ishikawa provides
several suggestions for developing cause effect diagrams. After factors are selected,
any interactions that are of interest should be noted. Experimental design is a
universal knowledge that can be applied to a wide range of products and processes.
The current investigation however, will also have to consider the limitations in the
experimental facilities, before making the final decision on the experimental factors
and their levels. One of the major influencing parameters in the current experiments
could have been the material for the test parts. In spite of several attempts on
different materials as discussed in Chapter 3, there was only one material that could
successfully be used on the experimental setup to print test parts by fused
deposition. While fabepoxy was a successful candidate, all other materials failed to
provide part that can be mechanically tested. This meant, dropping one of the most
important factors.
Further, filament size was considered to be an important factor, considering the
influence it would have on the inter-road diffusion and the overall meso-structure.
These inter-road and inter-layer diffusion characteristics were found to have
significant influences on the mechanical properties of FDM parts [30]. However,
when it comes to practically implementing this, there were numerous problems.
When the filament size is reduced, the total number of deposition paths would
change. For example, the number of roads will be doubled when the filament size is
halved. Though this could be easily implemented using the software solutions made
available for this work, the total time of deposition was also doubled, and considering
the manual attention needed on the machine, it became practically impossible to
control the quality of the printed part. After a number of trials, and considering the
inconsistencies, it was decided to drop this factor also altogether.
87