MT437 Unit 5 Pick Method Comparison Example

One Method for the Night, Another for the Day: An MT437 Unit 5 Pick Method Comparison for Two Order Streams

[Student Name]

Purdue University Global

MT437: Strategic Warehouse Management

Unit 5 Pick Method Comparison

[Instructor Name]

[Date]

Lookout Parts Supply's order profiles and every time standard are composite; each method is timed with the same inputs, and the sources cited are real.

Two Order Streams

The night stream is store replenishment: about 46 store orders averaging 96 lines each, 4,416 lines a night, spread across 28 shelving aisles of 180 feet. Stores are loaded onto trucks in departure waves from about 2:00 to 5:00 in the morning.

The day stream is rush orders, often called hot shots: about 280 orders a day, averaging 1.4 lines, each promised to a store within 45 minutes because a mechanic is waiting for the part.

Common Inputs

Every method is timed with the same inputs, so the comparison reflects the method rather than the assumptions. Finding, picking and scanning a line takes 27 seconds. Walking with a cart averages 175 feet a minute. Each tour needs about 2 to 3 minutes to set up totes and paperwork. Picking time is therefore the same for every method, about 33.1 hours a night for 4,416 lines; the methods differ in walking, sorting and coordination.

Discrete Picking at Night

In discrete picking, one picker picks one store's order from start to finish. Each store's tour walks about 5,650 feet, so 46 tours walk about 24.8 hours a night. With 33.1 hours of picking and about 1.5 hours of setup, discrete picking needs about 59.4 hours a night.

Batch Picking at Night

In batch picking, one picker picks four stores' orders at once on a cart with four totes. A batch tour walks slightly farther, about 6,100 feet, because it visits more aisles, but it covers four orders, so about 12 tours walk about 7.0 hours. Sorting each line into the right store's tote adds about 4 seconds a line, about 4.9 hours. With setup, batch picking needs about 45.6 hours.

Zone Picking at Night

In zone pick-and-pass, the 28 aisles are divided into four zones, each with its own pickers, and each store's tote passes from zone to zone. Walking within zones totals about 25.4 hours, because each zone visit still covers much of the zone for a 96-line order. Handoffs add about 1.2 hours, and waiting for totes when zones are unevenly loaded adds about 1.4 hours. Zone picking needs about 61.1 hours, the most of the four.

Wave Picking at Night

In wave picking, stores are released in groups that match truck departures, and within each wave, orders are batched four to a cart. Labor is close to batch picking, about 45.8 hours, because the batches are slightly less efficient when limited to one truck's stores. But wave release changes something batch picking alone does not: totes for each truck are finished just before it loads, instead of early in the night. The 5.6 hours totes now wait in shipping lanes, recorded in Unit 2, would fall to under an hour.

Batching saves the walking; waves save the waiting at the dock, and the night stream needs both.

The Day Stream

Rush orders are a different problem. A single order of 1.4 lines takes about 6.8 minutes to pick and check by itself. Batching rush orders would save walking but make each order wait for others to arrive, risking the 45-minute promise. Zone picking would add handoffs to a one- or two-line order. Discrete picking by dedicated rush pickers, starting each order as it arrives, keeps the promise. At about 31.6 picker hours a day, the rush stream needs about three dedicated pickers across the daytime hours, with a fourth at the midday peak.

What the Comparison Assumes

The timings assume pickers are fully loaded with work and that the warehouse system can create batches and waves. The current system can batch orders but releases them all at the start of the night; wave release requires a configuration change the vendor has quoted at about $4,000. They also assume the conveyor keeps up with batched totes, which it can at today's volume but might not in battery season, when heavier totes slow the check station.

The Recommendation

At night, adopt wave picking with batches of four stores per cart within each truck wave. It saves about 13.6 hours a night against discrete picking, about $98,300 a year at $24.10 an hour over 300 nights, and cuts the dwell time in shipping lanes. By day, keep discrete picking for rush orders with three to four dedicated pickers, and give the rush bench a location inside the fast zone, as Unit 10 proposes.

De Koster et al. (2007) describe the choice of picking method as dependent on order size, the number of orders and service deadlines, and the two streams here sit at opposite ends of each. Petersen and Aase (2004) found batching among the most effective single changes for orders of many lines, while Frazelle (2016) notes that urgent single-line orders are best kept out of batches altogether.

References

De Koster, R., Le-Duc, T., & Roodbergen, K. J. (2007). Design and control of warehouse order picking: A literature review. European Journal of Operational Research, 182(2), 481-501. https://doi.org/10.1016/j.ejor.2006.07.009

Frazelle, E. H. (2016). World-class warehousing and material handling (2nd ed.). McGraw-Hill Education.

Petersen, C. G., & Aase, G. (2004). A comparison of picking, storage, and routing policies in manual order picking. International Journal of Production Economics, 92(1), 11-19. https://doi.org/10.1016/j.ijpe.2003.09.006