This paper presents a new signal for analysis to identify and rank the bottlenecks in a manufacturing system. The proposed method analyses inter-departure time from different machines to identify and rank the bottlenecks. A simple descriptive measure with good correlation to bottleneck is presented. This research also presents a new method to allocate loss of production to different machines based on the analysis of inter-departure time. In addition, a set of rules that may be used to improve data integrity is presented. The proposed method may be used to analyse both steady-state as well as non-steady-state system behaviour. The proposed method is applicable to high-volume and low-variety manufacturing systems. Future research issues are discussed.