# Implementation of Digital Twin for Engine Block Manufacturing Processes
## 4 Results  
Programmed source codes and methods to create a faithful replica of the physical production line are shown in Figure 5. To verify and validate conformity of the simulation model with the real production line, a test of the correct logical sequence of operations was performed without real production data firstly. The simulation model was compared with a video recording from the real production line to achieve compliance of the virtual twin with the real production line. An agreement between the real and virtual production line can also be observed when comparing real data from the production line with the Gantt chart generated by the DT. TPS software allows CAD (computer-aided design) models to be implemented in the production line interface in STEP (Standard for the Exchange of Product Data) or JT (Jupiter Tessellation) file format to enhance visual aspect of the DT. Detailed 3D simulation model of the production line in the TPS software is presented in Figure 6. This model is able to reproduce, in near real-time, all actions of the physical twin using feedback from the embedded sensors. Figure 4: Digital twin mapping diagram between layers. Data from the real production line, recorded using the Echocollect device, were implemented into the simulation model. Recorded data contained the following parameters: signal sequence number, signal occurrence time, manipulation time for each operation, robots position/process, data collection point description, connection of each signal to its corresponding device in the simulation model, and the total production time. Remote monitoring of the production line parameters was possible through visualization of:  
* lead time (time interval from entry of the workpiece into the production process through the input conveyor to the removal of the workpiece from the output conveyor);
* cycle times and histograms for the CNC machines;
* throughput (the interval of occurrence of a casting at a given point);
* Gantt chart of the entire production line. Figure 5: Source codes, methods and charts developed in the Tecnomatix Plant Simulation software. Figure 6: Machining cell visualisation in Tecnomatix Plant Simulation. Remote monitoring through the DT refers to an ability to monitor and observer specific processes and operations within production without a physical presence in the production process. Remote monitoring involves observation of the physical production parameters through a dashboard or screen in a virtual world. Within DT, TPS software provides an interface for production line modeling with the ability to monitor physical production line status, while a personal computer represents viewing hardware. To increase production line productivity, the algorithm for bottlenecks detection was developed and implemented into the DT. The DT uses real-time data from the production line to detect bottlenecks. Implementation and synchronization of the data between the physical and virtual worlds in the DT is in real time, compared to the classical simulation that uses data that are implemented offline and only historical data can be implemented. Bottlenecks within a production line significantly reduce throughput of the system, so quick and correct identification of bottleneck locations can lead to an increase of system throughput. The algorithm for bottlenecks detection and prediction is based on the real-time production data. Bottleneck detection and diagnosis is one of the main roles of the DT. Based on the implemented algorithm to identify bottlenecks of the production line, it was possible to determine the following bottlenecks shown in Table 1. A bottleneck arises when the workload is higher than the workplace can handle in terms of capacity. In general, any system (conveyor, buffer, CNC machine, measuring station, piercing station, or robot) can become a bottleneck. The bottleneck detection algorithm reveals deviations from the standard processing, machining, or handling time. The DT records data on such occurrence into the table.