## 3 Results
### Degree of Particle Melt  
Using the MCM and core crystallinity values reported in Section 3.1, the DPM values for each sinter speed tested were calculated (Table 5). While an increase in the average \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **Melt Enthalpy (/g)** & **Crystallinity (\%)** \\ \hline Core (PA2200 Powder) & 112.3 & 53.6 \\ \hline MCM 1 & 65.5 & 31.3 \\ \hline MCM 2 & 68.0 & 32.5 \\ \hline MCM 3 & 62.3 & 29.8 \\ \hline Average MCM & 65.3 & 31.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Calculated values of MCM and core crystallinity obtained via DSC. Figure 5: DSC trace of a “fully melted” sample used to calculate MCM crystallinity, including a small core peak. DPM with increasing energy densities was recorded, this increase was found to be much smaller than anticipated and was accompanied by very large variability in the results within individual builds, providing little confidence in the repeatability and accuracy of the process. This was again attributed to the variability introduced by the lack of a standardised method for determining an appropriate baseline, rather than the absence of a change in DPM, due to clear changes in the ratios of MCM and core peaks in the raw DSC data (Figure 6). As the alternative method of calculating total crystallinity in the literature using peak height also required the establishment of an appropriate baseline, this was not considered viable. Therefore, based on the difficulties of repeatably processing the raw DSC data using established methods found in the literature, in addition to challenges obtaining a true MCM value for HSS parts, an alternative processing method was sought. In order to develop an alternative method for determining the DPM from DSC data, it was first necessary to establish a repeatable process for creating a baseline under any melt peaks. As the DSC data immediately following any melt peaks tend to produce a straight line, this section of the trace was identified as a useful reference point. Secondly, as the original definition of DPM was the percentage of melted and crystallised material within a given sample, it was decided to measure the area (melt enthalpy) of the MCM peak and compare it to the total area (combined MCM and core peak areas), eliminating the need to determine the MCM and core crystallinity values. Finally, reproducible temperature lines that bound and separated the MCM and core peaks needed to be established; these were selected to be the MCM peak onset, peak minima, and core peak end-temperatures. From this, the procedure outlined in Table 6 was developed, with the images in Figure 7 demonstrating how this can be achieved using the Perkin Elmer Pyris software. \begin{table}
\begin{tabular}{c c c c} \hline \hline \begin{tabular}{c} **Sinter Speed** \\ **(mm/s)** \\ \end{tabular} & \
\begin{tabular}{c} **Energy Density** \\ **Crystallinity (\%) [S.D.]** \\ \end{tabular} &
\begin{tabular}{c} **Average Total** \\ **[S.D.]** \\ \end{tabular} \\ \hline
140 & High & 39.3 [0.1] & 64.1 [0.3] \\ \hline
160 & Medium & 41.2 [5.0] & 55.6 [22.4] \\ \hline
180 & Low & 41.7 [1.3] & 53.1 [5.7] \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Calculated DPM values for each sinter speed (energy density) using the methodology established in the literature (S.D. = standard deviation). Figure 6: Changes in the ratio of MCM and core peak heights with varying sinter speeds (energy density). Using the procedure outlined in Table 6, raw DSC data from the three HSS builds were reprocessed to obtain alternative DPM values (Table 7). Whilst part crystallinity cannot be obtained via this method, from the table and the corresponding graph (Figure 8), a clear correlation between the sinter speed (energy density) and the DPM can be seen, with the