A dead metal zone is formed by the negative rake angle effect of the rounded-edge and it affects the cutting forces during machining operations. Therefore, investigating the size of the dead metal zone and changing it with cutting edge radius and flank wear rate are important. In this study, the dead metal zone was investigated experimentally for unworn and worn rounded-edge cutting tools and it was defined by changing the flank wear rate and cutting edge radius. It was observed that the size of the dead metal zone increased with increase of the cutting edge radius and it became smaller with increasing the flank wear rate. In addition, cutting force and thrust force were investigated. It was proven that both forces increased with increase of the cutting edge radius and the flank wear rate.