Within Define phase are articulated problem descriptions, objectives and metrics as well as solution strategy. The main goal was to identify and decrease expenses in the deburring department for aluminium castings through times and scrap reduction for at least 30% [8]. There were several major causes for the high expenses variability in castings quality, to many handcrafts, and to long control time. The main objectives of undertaken projects were to identify areas in the process where extra expenses exist, identify the biggest impact on production expenses, introduce appropriate measurement system, improve process and reduce expenses on production times, and implement improvements. An adequate metrics for evaluating projects success should be established. These metrics includes ratio volume/cost, labour cost, tool cost, scrap cost, number of nonconforming or defect parts per million (ppm), and Rolled Throughput Yield (RTY), the probability that a part will pass through multiple process steps without a defect. When the project was started, few useful historical data were available, so the first step was to collect and select these data in the deburring processes. On the base of the collected data decision about selection of process for improvement should be made, all process phases should be screened and appropriate action plan for minimizing variability within the process as well as reduction of production times prepared. In accordance to Six Sigma philosophy, Define, Measure, Analyse, Improve and Control strategy approach was employed. In accordance with DMAIC methodology, project goals should be defined, cross-functional teams formed including individuals with adequate process knowledge, historical information collected, and appropriate process selected for improvements. Furthermore, process map and cause and effect diagram should be define, process FMEA conducted and, based on obtained results, required actions and tools for process analysis selected. Appropriate action plans and design of experiment methods should be employed, and diverse control charts used for success monitoring.