# Optimization Processes in Automotive Logistic Flow
## Materials and Methods
### Description of the Logistic Flow Studied
#### 2.2.2 Description of the Logistic Flow  
The manufacturing process starts with the operator (OP3) picking up the EDL parts, the anti-roll bar, the anti-roll bar support, and the gusset. They are placed in the robotic welding cell 1 and fixed, after which the button is pressed to start the robot welding process. After welding the four components, the first subassembly is obtained, which is picked up by the operator and placed on the transport system (C1) to the second robotic cell. Within the robotic welding cell 3, the welding between the arm-bushing-damper shaft parts is performed. They are placed by the operator (OP1) on the cell feeding table and fixed, after which the welding process start button is pressed. Within cell 3, the second subassembly is made using the left/right shock arm-bush-shaft. After finishing the welding process, the parts are stored in a container in the station, and when the container is filled with 500 parts, it is transferred with the help of a forklift (T1) to the robotic welding cell 2. Robotic welding cell 2 welds Subassembly 1 (EDL + anti-roll bar + anti-roll bar support + gusset) with Subassembly 2 (arm + bushing + damper shaft) and two spring plates on the left and right sides. After welding these subassemblies and parts, the third subassembly is obtained (Subassembly 1 + Subassembly 2 left/right + Taler arch left/right). After welding Subassembly 3, it is picked up by the operator (OP2) from the station and put on the transport system (C2) to the preparation station. In the preparation station, Subassembly 3 is taken by the operator (OP4), placed on the preparation table in the station, and fixed, after which the assembly of the following parts begins:  
* Brake pipe support;
* Left handbrake cable support;
* Right handbrake cable support;
* ABS support;
* Left plate fairing support;
* Right-side plate fairing support;
* EDL fairing support. After the preparation is finished, Subassembly 3 is transferred by the operator (OP4) on the transport system (C3) to the robotic welding cell 4. Welding cell 4 performs the welding of Subassembly 3, which is formed in the previous stages, and Subassembly 4, which is made with the help of welding cell 5. Within welding cell 5, the operator fixes the following parts on a feeding table to form Subassembly 4:  
Figure 21: Rear-axle manufacturing logistic flow diagram. * Left axle head;
* Right axle head;
* Reinforcement of the left axle head;
* Reinforcement of the right deck head;
* Left/right axle head reinforcement;
* Left/right bridge head reinforcement;
* Left/right lower axle head reinforcement. Two such subassemblies are welded at the same time, after which they are picked up by the operator (OP7) and placed in the container for storage. When the container is filled with 500 parts, it is transported to welding cell 4, using a forklift (T2). The operator (OP5) takes two axle-head subassemblies from the container and fixes them on the feeding table and Subassembly 3, after which he presses the button to start the welding operation. After the welding process is finished, the operator takes the final formed assembly and places it on a gravity conveyor (C4) that carries out the transport to the quality control point. The operator (OP6) takes the finished part and places it on the quality control table, where he inspects the part, whether it is conforming or non-conforming. In this position, the engraving of the traceability series corresponding to the batch is also carried out. For all welding cords, 100% visual control is expected. In addition, a visual check is conducted at each PO by the station operator. In case of non-conformity of the cords, a label is applied with the non-conforming cord number, and they are evacuated by the station operator on a cart with the identification of the defect on the applied label. All transport/transfer times performed by all seven operators were calculated and included as parameters in the flow in the modeling phase. Next, the work points within the flow will be presented. 1.