## 3 Architectural Model
### Solutions for Monitoring a Plastic Injection Molding Production Line
#### 3.1.1. Telemetry of the Injection Molding Machine  
Modern injection molding machines have a large number of sensors and other monitoring elements that allow you to obtain a lot of data. These data can be exchanged by the presses with other information systems using special communication protocols; the most common ones are released by the Euromap organization and by the Open Platform Communications (OPC) standard [29; 30]. The data obtainable from the presses makes it possible to monitor the status of the production unit, a fundamental element for the analysis of interruptions. It is possible to precisely obtain the number and duration of individual machine stops, but it is not possible to obtain the cause of the stop because these data often disregard the data available from the press. Furthermore, the number of production cycles, the production parameters (temperature, pressure, etc. ), and other quality and process data are available according to the sensor equipment of the single machine and the information entered manually by the operator in the PLC of the machine. The sheets of the data obtainable from the presses are reported in Table 1. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Name** & **Variable** & **Description** \\ \hline Date and Time stamp & \(DTs_{i}\) & The variable is reported for each row when the value of any variable changes. \\ Machine ID & \(M_{i}\) & An ID is associated with each machine. \\ Status & \(S_{i}\) & Machine status can be either in production or stop. \\ Count outputs & \(N_{i}\) & The variable is a counter that is incremented by one unit for each print cycle. \\ Defect & \(D_{i}\) & The variable is a Boolean that is 0 if the unit is good and 1 if it is defective. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Datasheets: telemetry of the injection molding machine. Figure 6: Architectural model. Through the data collected via the injection molding machine's telemetry, for every machine \((M_{i})\), it is possible to calculate the OEE [13,15], considering its three fundamental elements. Availability is defined as follows:  
\[\text{Availability}(\text{A})=\frac{\text{Operating Time}}{\text{Operating Time}+\text{Downtime}}=\frac{\sum S_{1}}{\sum S_{1}+\sum S_{0}} \tag{1}\]  
where Operating Time and Downtime are collected from the telemetry. Operating Time is calculated as the sum of the time that the machine is in the \"in production\" state \(S_{1}\). Downtime is calculated as the sum of the time that the machine is in the \"stop\" state \(S_{0}\). Performance is defined as follows:  
\[\text{Performance}(\text{P})=\frac{\text{Actual Output }(\text{units})\ \times\ \text{Theoretical Cycle Time }(TCT_{i})}{\text{Operating Time}}= \tag{2}\] \[=\frac{\sum N_{i}\times TCT_{i}}{\sum S_{1}}\]  
where Actual Output (units) is obtained by the \"count output\" variable from the telemetry, while Theoretical Cycle Time can be obtained using an article information database. Quality is defined as follows:  
\[\text{Quality}(\text{Q})=\frac{\text{Actual Output}(\text{units})-\text{ Defect Amount }(\text{units})}{\text{Actual Output }(\text{units})}=\frac{\sum N_{i}-\sum D_{i}}{\sum N_{1}} \tag{3}\]  
where Defect Amount (units) is collected from the telemetry, summing the defect units in the chosen time interval. In some cases, for example, for older injection machines that do not have a system for defect recognition, this information will be taken from the Enterprise Resource System (ERP) or manually by operators. In order to obtain a complete calculation of the OEE indicator, it is also necessary to accurately collect the causes that determine a stop of the production unit and the reasons that lead to a product being deemed non-compliant. The information reported is not obtainable from the telemetry data made available by the PLC of modern plastic injection molding presses. This information, therefore, must be collected manually by the process operators.