# Optimization of Wiring Harness Logistics Flow
## 3 Results and Discussion
### Proposed Structure of the Assembly Line Simulation and Analysis in WITNESS Horizon Software  
Comparing the results from the initial system simulation with the ones obtained after applying the mathematical model, it can be observed that the mathematical model shows that other optimization solutions might still be available for increasing productivity. Cycle times for the workstations included in the newly proposed system architecture were calculated considering the proposed mathematical model. The solution to converge to a time within the range [5.32; 5.43] minutes is to modify the architecture of the wiring harness. For example, assuming that the harness has a thicker branch (main branch) ending in three or four smaller branches (secondary branches), one branch can be separated from the main branch. In this way, a better equilibration between the workstations can be achieved. However, optimizing assembly time by modifying the wiring harness architecture faces many constraints related to the vehicle environment, like difficulties in ensuring the right path of the harness due to the lack of fixation points in the vehicle or proximity to sharp edges. This is why cycle times for some workstations will not be defined within the range [5.32; 5.43] minutes in the following simulations for the proposed structure of the assembly line. Two production shifts were simulated in WITNESS Horizon Software to obtain data regarding the proposed structure's efficiency and to identify aspects that may need adjustments. WITNESS Horizon simulation was used to model the proposed system architecture and diagnose the key performance indicators associated with the proposed system configuration. Using WITNESS Horizon, the system's configuration was modified to correspond to the new characteristics and to obtain an optimized system version. The proposed structure of the assembly described in Figure 8 is composed of two lines that follow the same structure, as described below:  
* Dynamic assembly line 1--8 workstations with 8 operators (OP1-OP8)/Dynamic assembly line 2--8 workstations with 8 operators (OP26-OP33);
* R1--preassembled elements trolley after dynamic assembly line LAD Section HAL 1/R5--preassembled elements trolley after dynamic assembly line LAD Section HAL 2;
* Rotary assembly line 1 (conveyor)--10 workstations with 10 operators (OP9-OP18)/ Rotary assembly line 2 (conveyor)--10 workstations with 10 operators (OP34-OP43);
* R2-R4--harness trolleys after rotary assembly line LAD Section HAL 1/R6-R8--harness trolleys after rotary assembly line LAD Section HAL 2;* Scrap--trolley for rework/scrap after electrical control hybrid assembly line 1/ Scrap01--trolley for rework/scrap after electrical control hybrid assembly line 2;
* CT_QC--clip test/quality check hybrid assembly line 1 (2 workstations with two operators OP19 and OP20)/CT_QC01--clip test/quality check hybrid assembly line 2 (2 workstations with two operators OP44 and OP45);
* EC_VT--electrical control/vision camera check hybrid assembly line 1 (2 workstations with two operators OP21 and OP22)/EC_VT01--electrical control/vision camera check hybrid assembly line 2 (2 workstations with two operators OP46 and OP47);
* Packaging hybrid assembly line 1--one workstation with one operator (OP23)/Packaging hybrid assembly line 2--one workstation with one operator (OP48). After modeling the assembly line's proposed structure, the trajectories of the mobile entities were established, and various system parameterization versions were tested based on the values calculated considering the proposed mathematical model; system simulations were performed, and the best system version was identified. Several simulations were performed to optimize the system by changing and testing the parameters for work points and operators. The version with the most significant productivity increase was kept without bottlenecks and large waiting times. Figure 8: Proposed structure of the assembly line made in WITNESS Horizon.