Production systems where more flexible production can be realized with smaller parties is a very important need for companies in today's market conditions. In order to meet this need, companies benefit from lean manufacturing techniques. Lean production is a production system in which businesses eliminate operations that consume resources and do not create value. In this study, SMED (Single Minute Exchange of Die), which is one of the methods of lean production, was used. SMED is a method used to shorten the setup time required for production transition between two different parts and to provide flexibility in production. In the scope of the study, SMED was used to improve the mold change times in a press in a steel pipe company which produces pipe fittings in the heavy industry sector. Setup times were determined by using video analysis method in a sample mold change process. Two different mold changing processes are carried out in the plant during the product transition. All the steps in these procedures were examined in detail and suggestions for minimizing waste were presented. As a result of the determination of operations which can be done in parallel, operator assignments, method study, 5S and standardization studies, the internal mold change time in the mold change process has been reduced from 51 minutes to 17 minutes, and the external mold change time has been reduced from 184 minutes to 70 minutes. A total of 63% improvement was achieved in the mold change time. In addition, ergonomic analysis for mold change was made and the power consumed by the operator during the preparation period decreased from 299 Watts to 165 Watts.