A Flexible Control for Manufacturing Automated Electroplating Lines

This paper presents a design approach for a flexible control of automated two-hoist electroplating lines. Several manufacturing plants, particularly the printed circuit board (PCB) industry, use electroplating lines for surface treatment of parts. Several constraints such as nb-wait in process and time interval durations make hoists control a complex task. Here, the proposed control architecture is made of an upper and a lower control module. The upper control module decomposes the two-hoist line into single hoist sub-lines and computes their associated hoist sequences. Each sequence is modeled by the lower control module using discrete event P-time Petri nets (P-time PN). At this module, critical structures are defined and used to calculate a cycle time interval for each sub-line. An algorithm is also proposed to compute P-time PN firing time instants. The proposed approach is tested on a two-hoist electroplating system made by Telemecanique (MD1AE244). The flexibility of the control is characterised and used to absorb delays affecting part entry times. This leads to a simplified control by avoiding the need for hoist moves rescheduling if faced with unexpected delays.