# Conceptual and Preliminary Design of a Shoe Manufacturing Plant
## 7 Comparison between Both Processes  
Once the simulations were carried out using an expert system for both processes, they were compared taking into account factors such as time per product, efficiency, and the number of workers, thus obtaining more analytical data on the plant design. Table 3 shows how every operation (after the cutting process) is considered for both processes, the number of workstations modelled for each group of tasks in order to keep the limiting factor at full capacity, and the average efficiency of the workers.  
The processes that are shown in the Table 3 together with the cutting, packing, and entry/exit in the rotary injection machine operations involve a total of 37 workers for direct injection and 33 workers for mounting and cementing to allow the proper development of the system.  
Table 4 shows the summary of the resources needed for the mounting-and-cementing process in order to accomplish the purpose of optimisation and efficiency of resources, these operations are additional in this process and are not needed in the direct injection. Therefore 10 workers are needed. Considering the operations shown in the tables together with the cutting and packing, an amount of 37 workers for direct injection and 43 workers for mounting and cementing are required.  
These results are coherent and in line with expected data. The direct injection process is characterised by a higher production volume with fewer workers, which means higher productivity per worker and work shift. On the other hand, the mounting and cementing process involves a lower initial investment in machinery and although the system is less  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Process** & **Time per Product (s)** & **N of Workers** & **Efficiency** \\ \hline Toecap mounting & 17 & 1 & 89.00\% \\ Heel and shank mount & 17 & 1 & 86.00\% \\ Brushing and marking & 26 & 2 & 67.50\% \\ Gluing sole and upper & 40 & 3 & 76.00\% \\ Press outside bounding & 38 & 3 & 61.66\% \\ \hline \hline \end{tabular}
\end{table}
Table 4: Features of optimal sequence for Manufacturer 1 and summary of characteristic operations of the mounting-and-cementing modelled.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Process**} & \multirow{2}{*}{**Operations**} & \multicolumn{2}{c}{**Time per Product**} & \multicolumn{2}{c}{**N Workers**} & \multicolumn{2}{c}{**Efficiency**} \\ \cline{3-8}  & & **Operation Time** & **Total Time** & **DI** & **M\&C** & **DI** & **M\&C** \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Milling and preparations tasks \\ \end{tabular} } & Upper marking & 30 & & & & & & \\  & Tongue marking & 9 & & & & & & \\  & Milling & 30 & 114 & 7 & 6 & 88.57\% & 86.67\% \\  & Temporary unions & 45 & & & & & & \\  & Toecap sewing & 37 & & & & & \\  & Quarter sewing & 67 & & & & & \\ Stitching & Heel sewing & 37 & 141 & 9 & 8 & 83.93\% & 82.21\% \\  & Gluing tongue, upper, and lining & 52 & & & & & \\  & Gluing upper and lining & 47 & & & & & \\ Manual labours & Gluing foam & 22 & 121 & 8 & 7 & 81.70\% & 80.60\% \\  & Top moulder & 52 & & & & & \\  & Heel moulder & 52 & & & & & \\ Preshaping & Eyelets & 36 & 140 & 9 & 8 & 81.96\% & 79.04\% \\  & Last removal & 6 & & & & & \\ Finishing & Cleaning & 13 & & & & & \\  & Insole and shoelace & 51 & 70 & 4 & 4 & 88.00\% & 78.00\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Summary of modelled processes. This information is associated with the direct-injection and the mounting-and-cementing process.  
efficient, it allows flexibility in production by adapting the number of workers. In other words, direct injection is significantly more profitable if production is close to the maximum, but for lower productions, profitability tends to be similar in both cases and the return on investment (ROI) grows. In this case, the mounting and cementing process is more attractive for producers.