Bond Work Index Test Ball Mill.US. $. 13,800. The FCBond Work Index Test Ball Millwas designed by F. C. Bond for use in determining the Bond Index, a measure of grindability and power required for grinding applications. The FCBond Millsare used in laboratories throughout the world. A copy of Fred C.Bond’sMethod of Crushing and Grinding for determination of theBond Indexis included with each mill.