Wave Release Strategies for Order Fulfillment Systems with Deadlines

Abstract

A distribution center is ultimately in the business of shipping orders. Because every customer's experience is determined by how timely and accurately an order is received, distribution centers should focus not only on how fast they process orders, but also on keeping their operations synchronized and delivering orders on time. In traditional distribution centers, including internet and catalog ful llment systems, synchronization and economies of scale are achieved with "waves." A wave is a large group of orders that are picked and packed together, sorted for individual customers, and shipped. Problems arise when those internal processes are not properly coordinated. When operational parameters, such as number and timing of waves, are not planned systematically, missed orders and upset customers are the result. We present the first systematic investigation of wave planning in order ful llment systems. We develop continuous fluid models of work content in an order ful llment system, in order to determine the optimal timing and number of waves with the goal of maximizing service performance against a deadline-oriented metric.