The location of storage racks for high-demand, highpriority goods, and its distance to the warehouse entrance
and departure area are the factors affecting the efficiency of
order picking. Shorter travel time and lower cost are needed
with the better plan considering the material storage by
popularity. It takes an average of 99.6 h to process one type
of goods with picking, sorting, packaging, and shipping,
with the time measurement by stopwatch. Figure 4 shows
the bottleneck operation and key improvement steps in the
blocks with dark background.