A particular feature of solid products is that their properties are determined by the disperse state. For many products, rigorous demands are made by customers on the range and width of the particle size distribution. In order to achieve the right particle size distribution in the production process, a milling step is often necessary. In this paper, the route from the required product and process properties to the installed milling facility will be shown for impact rotor mills and stirred ball mills. Other aspects influencing the grinding process agglomeration or combination with classification - are discussed as well as measurement needs, new developments and research requirements from the point of view of the chemical industry.