Application of the Cube-Per-Order Index Rule for Stock Location in a Distribution Warehouse

Consider a distribution warehouse divided into reserve storage and staging areas. The warehouse stores a variety of items and receives orders for any combination of items. Goods are moved from reserve storage to staging area, where they are selected to fill the given orders. The problem is to locate items in the staging area in order to minimize the expected labor costs of order selection. Several years ago, J. L. Heskett [Heskett, J. L. 1963. Cube-per-order index—A key to warehouse stock location. Transportation and Distribution Management3 (April) 27–31.] proposed a criterion, called the cube-per-order index (CPO) rule, for solving this problem. The criterion was justified heuristically by means of numerical examples. Recently [Kallina, C. 1976. Optimality of the cube-per-order index rule for stock location in a distribution warehouse. Working paper, American Can Company, March.], one of the authors has shown that the class of problems considered by Heskett can be formulated as a linear program, and that the CPO rule is in fact the optimal solution. In this present paper, we will (1) summarize some basic background material, (2) describe the computational steps for implementation of the CPO rule, and (3) discuss some practical conclusions gathered from experience in actually applying the rule to assist in warehouse layout.