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is possible to obtain injected parts with lower injection times and packing pressure
equal to injection pressure. Figure 8.15 shows the images from Fig. 8.14 magnified
2,000 times. At this magnitude, micro cavities on the surface can be observed.
However, micro cavity size is shown to be reduced as injection time decreases. In
the least favorable condition, the order of magnitude is 3 lm at most. Literature
shows that a well-defined rugosity in terms of Ra and Rz is beneficial to the quality
of polymer/metallization interface bonding [ 11 ].
8.4 Conclusion
Analysis of thickness of layers deposited has shown that these are in the range
recommended by the literature. Optical microscopy with image capture has shown
to be adequate for this analysis. Copper layer could be decreased in 1 lm and
nickel layer could be decreased in 5 lm. The method used for analyzing the
morphology of the treated surface correlated to the surface residual stress obtained
through ABS injected molding has shown to be consistent with the use of a
combination of statistical, numerical, and experimental tools. The tool for statis-
tical design of trials has helped in organizing and defining the setting parameters of
injection to be tested. This in turn has enabled greater efficiency in the relationship
between number of trials and data on the relevance of each parameter. The central
composite design statistical experiment has shown to be the most adequate for
achieving response surfaces in the trial analysis phase. The major contribution
from this study is the demonstration through trials that it is possible to obtain
surfaces with adequate residual stress which are not significantly affected by acetic
acid, therefore being adequate surfaces for the metallization process. Parts were
obtained from low to high injection times where packing pressure was always
equal to injection pressure. A more detailed analysis through electron microscopy
with 2000 magnification showed that, for lower injection times with roughly the
same simulated residual stress, the surface is less susceptible to acid attack.
References
1. Murakamik, H.E., Bom, R.P.: Process parameters influence on residual stress on injected
parts surface. In: Proceedings of the 63rd ABM Annual Congress, Santos, p. 626-635 (2008)
2. Murakami, E.H.: (2009) Process parameters influence over the ABS injected parts residual
surface tension. Master Science Thesis on Materials Science and Engineering, University of
Santa Catarina State, CCT, Joinville, p. 99
3. Turnbull,
A.,
Maxwell,
A.S.,
Pillai,
S.:
Residual
stress
in
polymers—evaluation
of
measurement techniques. J. Mater. Sci. 34, 451-459 (1999)
4. Jansen, J.A.: Environmental stress cracking—examples from the automotive industry,
Society of Plastics Engineers, ANTEC. In: Proceedings of Plastics: Annual Technical
Conference, vol. 3, Special Areas (2005)
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