Zone shapes in class based storage and multicommand order picking when storage/retrieval machines are used

In this paper the effect of the zone shape in a class based storage on the optimal picking tour of the S/R machine is investigated. The expected value of S/R machine travel time for multi command order picking is derived as a function of number of addresses and area of the rack. This is used to model the two zones of fast moving products in a three class storage system. Each of the three investigated configurations was tested by computer simulation in a full factorial experiment. The results are presented and indicate that each of the proposed configurations perform well and could be used in practice.