Biomedical Engineering Reference
In-Depth Information
FIGURE 11.7
The particle morphology and corresponding size distribution for large particle size, sieved between 75-150
m
m
(
n
= 105) and small particle size, sieved at
<
75
m
m, (
n
= 300).
by looking at powder flowability, layer thickness, binder imbibition, and most noteworthy, the sintering
protocol as a function of powder particle size. Small particles tend to have poor flowability (
Butscher et
al., 2011
) and are inclined to agglomerate. This effect causes limited powder compaction during layer
spreading (
Shanjani et al., 2011
) and may explain the poor mechanical strength of the samples manu-
factured using powder with small particle size in this chapter. The parts with the lowest performance
were the dual powder composition samples. This may have been caused by stresses occurring at the
interface between the two powder types during sintering, as indicated by the fracture patterns occurring
at that location. Another aspect that influences part strength is the sintering process. In this work, all
samples were subjected to the same sintering protocol, optimized for the 75-150
m
m powder particle
range.
Figure 11.8
b illustrates examples of sintered CPP samples corresponding to the three categories
of manufactured parts. It can be seen that the parts have a significantly different color, indicating that
sintering had a different effect on samples, depending on powder size composition. A more in-depth
investigation into an appropriate sintering protocol for samples with different powder size layer com-
position should be investigated.
The important achievement of this work is in demonstrating the feasibility of using multiple pow-
ders during the multiscale 3DP manufacturing process, which advances the current state of powder-
based AM toward new manufacturing opportunities. Further investigations into increasing the perfor-
mance of this approach are currently underway.
Search WWH ::
Custom Search