Corn is cultivated mostly in all countries for its high consumption, quality, and food value. Corn residuals, including stalk and cob, are also considered as the most abundant biomass resource and animal feeding. Shortening corn stalks into different sizes is an important pre-process to make animal food and biomass. Reducing shearing force is one of the most effective way to save energy in such process. This paper presents experimental results to optimize the cutting force by varying approach angle and feed angle, the two parameters representing the relative motion of the stalk and the cutter. Optimum design of experiments were planned through three stages: screening, steepest descent andoptimal experiments. Compared to a typical condition in commercial choppers, where these angles are usually set to be 0°, the optimal setting provided a five-time smaller cutting force. The results obtained thus is very promising for further studies to optimize devices of forage cutting.