# Optimization of Wiring Harness Logistics Flow
## 2 Materials and Methods
### Case Study: Increasing Production Capacity by Proposing a New System Architecture
#### 2.3.2 Initial Structure of the Assembly Line Simulation and Analysis in WITNESS Horizon Software  
To obtain data regarding the efficiency of the assembly line's initial structure and identify aspects that may need adjustments, a simulation of two-shift production was carried out in the WITNESS Horizon Software. WITNESS Horizon was used for modelling the initial system architecture, and a simulation of two shifts of production was carried out to diagnose the key performance indicators associated with the initial assembly line and identify necessary changes to optimize the system as required (to double the production). The line structure described in Figure 3 is composed of the following:  
* FW1-FW6--6 fixed workstations with 6 operators (OP1-OP6);
* R1-R3--preassembled elements trolley;
* Rotary assembly line (conveyor)--20 workstations with 20 operators (OP7-OP26);
* R4-R6--harness trolley;
* Scrap--trolley for rework/scrap;
* CT_QC--clip test/quality check (2 workstations with 2 operators OP27 and OP28);
* EC_VT--electrical control/vision camera check (2 workstations with 2 operators OP29 and OP30);
* Packaging--1 workstation with 1 operator (Op31). \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Output Production** & \\ \hline
800 & 160 & 80 \\ Per week (5 days) & Per day (2 shifts) & Per shift \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Output production is based on volume estimation and a basic work schedule. The parameters for each workstation and operator were defined. A diagnosis for the initial system's configuration was given to identify bottlenecks and long waiting times. The results are presented in Figures 4-6. Figure 4: Diagnosis results for FW1–FW6. Figure 3: The initial assembly line during the simulation in WITNESS Horizon. The results for FW1-FW6 show that six fixed workstations with six operators are blocked for between 7.33% (FW3, FW4, FW6) and 9% (FW1, FW2, FW5) of the total simulation time. For FW1, idle time is 8.33%, and busy time is 82.67%. The busy time for FW2 and FW5 is 91% of the total simulation time, and the busy time for FW3, FW4, and FW6 is 92.67%. Operators OP7-OP16 are allocated to 10 workstations from the left side of the rotary assembly line. The workstations for OP7 and OP8 are blocked for 8.83% and busy for 91.17% of the total simulation time. The workstations for OP9 and OP10 are blocked for 1.67% and busy for 98.33% of the total simulation time. The workstations for OP11 and OP12 are busy 100% of the time. The workstation for OP1  
86%, the workstation for OP14 is idle for 12.33% and busy for 87.67%, the workstation for OP15 is idle for 10.67% and busy for 89.33%, and the workstation for OP16 is idle for 9% and busy for 91% of the total simulation time. Operators OP17-OP126 are allocated to 10 workstations from the right side of the rotary assembly line. The workstation for OP17 is idle for 10.65% and busy for 89.35%, the workstation for OP18 is idle for 10.45% and busy for 89.55%, the workstation for OP19 is idle for 7.19% and busy for 92.81%, the workstation for OP20 is idle for 8.82% and busy for 91.18%, the workstation for OP21 is idle for 5.56% and busy for 94.44%, the workstation for OP22 is idle for 7.33% and busy for 92.67%, the workstation for OP23 is idle for 9% and busy for 91%, the workstation for OP24 is idle for 7.17% and busy for 92.83%, the workstation for OP25 is idle for 6.17% and busy for 93.83%, and the workstation for OP26 is idle for 5.17% and busy for 94.83% from the total simulation time. The bottlenecks are caused by the differences between the cycle times defined for each workstation and operator. The results show that a productivity of 132 pieces was obtained for two shifts. The productivity of 132 pieces resulting from the simulation is lower than the estimated 160 pieces. Also, the \"Takt time\" given by the simulation is 6.80 min, which is lower than the calculated \"Takt time\" of 5.63 min.