Ground Planning Optimisation of a Shoe Injection Machine

The challenge proposed by ara Shoes Portugal was to improve the efficiency of a shoe injection machine, using as the main indicator the Overall Equipment Effectiveness (OEE). To do that, the focus was on planning the shoe injection machine to minimise cycle losses while maximising the production of different articles. This challenge could be identified as a Scheduling Problem (SP), a well-known class of NP-hard problems. To tackle ara's challenge, a novel mathematical model was developed that addressed the machine characteristics and the current practices on the company's shop floor. The model was solved using a commercial solver, and new heuristics were also put forward. These approaches were tested on a new instance based on real data. Results allowed us not only to draw conclusions on the potential gains of using these approaches but also to gain insights into the appropriateness of current scheduling practices.