Failure to meet delivery deadlines in the metalworking sector is challenging for many maintenance companies. This article analyzes a case study of a mechanical maintenance company offering high non-compliance rates due to stock outs. To address this challenge, supply management guidelines are proposed based on the Green Purchasing philosophy, thus improving purchasing processes, supplier selection, risk management, and reducing environmental impact to achieve the objective of reducing lead time by two days, supplier on-time delivery by 96%, and in-full delivery by 95%. The case study concludes with the improvement of supply management, timely service delivery, carbon footprint reduction, and good environmental practices.