a fluidizing mixer works a mixture of materials , such as polyvinyl chloride resin , together with plasticizers and liquid stabilizers and the batch is then discharged at the end of a work cycle of operation . the mixer employs an electrically energized driver which drives a working member , such as a high speed mixing blade , such that electrical energy is expended as work is being performed on the material . during each work cycle of operation the amount of expended electrical energy is sensed for purposes of providing a work signal having a value in accordance with the energy being expended . a work cycle is terminated when the amount of energy being expended to work the material decreases by a given amount .