Problem 1

(a) Why is the receiving staff in a typical warehouse much smaller than the staff of order-pickers?
The receiving staff in a typical warehouse is much smaller than the staff of order pickers because restockers move larger quantities of SKUs, so a few receivers can keep many pickers supplied. A rule of thumb is that there should be one receiver for every five order pickers. Receivers usually handle products in larger units and order pickers handle products in smaller units. Order picking is significantly more labor intensive and resistant to automation. (b) Explain the difference between popularity and demand.
Demand is considered the forecasted frequency of SKUs and popularity are the A items that have a high frequency and are picked and packaged often. For example, a Christmas related SKU will have a high demand during the holiday season but is certainly not popular other seasons.
(c) What is “batch picking” ? Give a pro and a con of batch picking.
Batch picking is when each worker retrieves many orders in one trip. An advantage of batch picking is that it is a way to increase the pick density. However, a disadvantage is that it requires that the items be sorted into orders while picking or somewhere else downstream. If they are sorted into orders during picking, pickers are slowed down because they must carry a container for each order and they must sort the items as they pick, which leads to time being wasted and can result in errors. If the items are sorted downstream, extra space and labor needs to be devoted to the additional process.

Problem 2

(a) Which type of storage generally makes pallets more accessible: Pallet flow rack or drive-in rack? Explain.
Drive-in racks allow lift trucks to drive within the rack frame to access interior loads, but to avoid double handling, all levels of each lane must be assigned to a single SKU. Product is moved with a FIFO policy, supported by ballets entering from one end of the lane and leave from the other. Drive-in racks do not enable the access flexibility that other types of pallet rack achieve, specifically the pallet flow rack. Pallet flow racks are deep lane racks where the shelving is slanted and lined with rollers, so that when a pallet is removed, the remainder will be pulled to the front. This gravitational system enables pallets to be put away at one side and retrieved from the other, preventing storage and retrieval operations from interfering with each other. When considering drive-in rack and pallet flow rack, the latter generally makes pallets more accessible.
(b) In a warehouse with conveyors, conveyable skus should be stored far from shipping; why?
In a warehouse with conveyors, conveyable SKUs should be stored far away from shipping because it can travel for free. Non-conveyable SKUs should be stored close to shipping because they have to be carried.

Problem 3

Suppose you are laying out a floor stack area with an aisle 14 feet (4.3 meters) wide to accommodate forklift trucks. All pallets are 48 by 40 inches (1200 by 1000 mm) and are stored with the 40-inch side facing the aisle. Assume that each sku experiences demand that is constant and is reordered once each inventory cycle as below. SKU | Order Qty (pallets) | Stack height (pallets) | Order cycle (weeks) | A | 20 | 2 | 4 | B | 24 | 3 | 3 | C | 12 | 1 | 6 | D | 4 | 3 | 2 |

a) For each SKU, compute a space-efficient lane depth.
Lane Depth A = 14/42202=4.2=4 pallet positions Lane Depth B = 14/42243=3.7=4 pallet positions Lane Depth C = 14/42121=4.6=5 pallet positions Lane Depth D = 144243=1.5=1 or 2 pallet positions
b) Compute a single, common lane depth that will be space-efficient for the set of SKUs. Common lane depth = 144214202+243+121+43=3.7=4 pallet positions

Problem 4

Consider a collection of pallets of paint of various kinds. Each sku will be floor- stacked 4 pallets high. Which skus are best stored in the area of the warehouse with lane depth of 3 pallet positions and an aisle 3-pallets wide? 2.5 <32qi4<3.5 6.25<3qi8<12.25 16.7<qi<32.7
The SKUs that are best stored in the area of the warehouse with lane depth of 3 pallet positions and an aisle 3 pallets wide are those SKUs with between 17 and 33 pallets.

Problem 5

What is “honeycombing” and why is it a problem for warehouses? What techniques or tools can be used during the phase of warehouse design to reduce horizontal honeycombing? Vertical honeycombing?
Honeycombing is the loss of storage capacity in floor space because of the need to store single SKUs in a vertical column or horizontal lane. Lanes that are too short have a large part of floor space that is devoted to aisles, if lanes are too long the floor space in front of the back pallets are underutilized. Pallets that can’t be stacked easily, result in the loss of available height. In order to avoid honeycombing, full lane depth optimization should be completed to reveal the optimal mix of storage lane depths. Full lane depth optimization assigns each SKU to the lane depth that will minimize the total operating costs (i.e., floor space, labor, equipment). Proper planning, size stacking, the use of short rows along edges of block stacks, and the use of short rows in block can also be used to reduce honeycombing.