While setting up grinding processes for optics fabrication, the optimum tool and process parameters have to be chosen. Unfortunately, datasheets of commercial grinding tools contain only information about grit type and size, bond material, tool shape etc., leaving out any information about process parameters to be applied or tool lifetime or performance. For this reason, tools and machining parameters are commonly adjusted during iterative experimental test runs using actual workpieces from production batches which is time consuming, expensive and without guarantee that the optimum set of machining parameters are achieved. In this paper we present a method to determine grinding tools process window for a given workpiece material. That way, ideal machining parameters can be determined offline for maximum reliability and productivity. In addition, the gained data provides the basis to identify the most suitable grinding tool for the desired application.