PSI - Issue 77

Carolina Francisco et al. / Procedia Structural Integrity 77 (2026) 567–574 C. Francisco et al. / Structural Integrity Procedia 00 (2026) 000–000

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temperature, therefore, provides an indirect method to assess the condition of the bearing and crankshaft. One practical method is to measure the bearing temperature directly by installing thermocouples within the journal bearing, providing data for condition monitoring Laubichler et al. (2022). • Gearbox and Motor The servomotor powers the press and enables programmable motion, while the transmission system converts this motion into usable movement for the shaft. Degradation of gearbox components can a ff ect the performance of connected parts, particularly the crankshafts that drive the slide, which, in combination with the tool, ap ply the stamping load. Monitoring gearbox vibrations allows the detection of anomalies such as bearing wear, misalignment, gear tooth damage or imbalance. The vibration response of the gearbox directly reflects its me chanical health, so analyzing the vibration signals enables condition assessment of its elements Seo et al. (2024). In addition, data collected from the servo-driver related to the servomotor can indicate anomalies hap pening in other components. For example, motor current signature has been used to identify gear and bearing faults through frequency domain techniques J. Jung et al. (2015).

Fig. 2: Press main components to monitor, their failure modes and proposed sensor approach.

Based on the analysis, the proposed sensing plan recommends the implementation of load sensors on the tool and frame, accelerometers on the slide, frame, and gearbox, temperature sensors on the crankshaft journal bearings, and the collection of motor data from the servo driver, as illustrated in Figure 2. All sensors are connected to a data acquisition system (DAQ) that communicates with a local computer for data transmission. The acquired data are stored in a local database, from which the monitoring platform retrieves information for processing and condition assessment. Additionally, the press’s PLC can transmit operational parameters to the same database to complement the sensor data. 2.1.1. Processing and monitoring Depending on the data type, di ff erent processing methods are used to assess the condition of each component. From acceleration signals, time and frequency domain features are extracted to obtain the vibration signature of the slide and frame. Temperature data from the journal bearing is used to estimate the viscosity of the lubricating oil and, consequently, the lubrication regime. The applied load, combined with motor current and slide displacement, enables the estimation of energy losses and the derivation of force–displacement curves that characterize the process. Establishing a reference curve from normal, healthy press operation allows operating limits to be defined. During