Revisiting Industry 4.0 with a Case Study

The Industry 4.0 is becoming a hot topic. In this paper, we revisit Industry 4.0 from the perspectives of its purposes, features, and key performance indicators. We present a reference roadmap for advancing an Industry 4.0 project from plan to implementation. We present the case study of steel industry 4.0 and lessons. In addition, we give suggestions directing the advancement of Industry 4.0.