American psychologist Abraham Maslow once wrote, “I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.” Most of us are familiar with this this concept, which is known as the law of the instrument, or simply Maslow’s hammer.
The quote implies that the ability to correctly identify a problem is limited to the tools at one’s disposal. The tools available to supply chain managers range from the extremely basic to the most sophisticated—and more seem to be introduced each day. However, it is our responsibility to become familiar with them, learn their applications, and use them effectively.
The Division of Supply Logistics at New York City Transit (NYCT) focuses on the receipt, warehousing, transportation, and issuance of materials used in the maintenance and repair of subway cars and bus fleets. Therefore, the solutions we employ fall into the general categories of warehousing, picking, transportation, and inventory control. As is typically the case, the two areas that compose the greatest cost— inventory and labor—are involved in warehousing and picking.
In order to determine which warehousing tools to use at NYCT, we have found that it is best to first identify how material enters and exits the facility. There are generally four or five ways this can happen. Then, our storage options include a mixture of low-tech, medium-tech, and high-tech solutions. (These also can be considered low-volume, medium-volume, and high-volume or low-cost, medium-cost, and high-cost.) The solutions we choose are general concepts—such as selective storage, pallet-flow racks, pick to light, vertical and horizontal carousels, and mini-load systems—all of which should be familiar to the experienced warehouse professional.
Most large operations use several different tools, and the Division of Supply Logistics is no exception. But the greatest advantage is that, by opting for a combination of in-out options, our warehouse solutions are just as varied and precise. We employ bulk stacking, selective and double-deep pallet racks, standard- and narrow-aisle configurations, shelf storage, storage cabinets, and vertical carousels. This configuration provides the best material control.
Picking is usually the area of the warehouse that consumes the lion’s share of the labor cost, so most organizations (including NYCT) are continuously trying to increase picking productivity and reduce costs. There are basically two order-picking concepts: move the picker to the part or move the part to the picker. Picker-to-part solutions include picker to pallet, picker to cart, and picker to conveyor. In high-volume, high-tech operations, a man-aboard storage-and-retrieval machine may be used. Part-to-picker applications include the use of horizontal and vertical carousels, mini-load systems, or automated storage/retrieval systems.
Independent of the picking concept, the best picking option is determined by the warehouse applications used, shipping methods, and customer requirements. For zone, batch, and wave picking, my team has found that it is most effective to have space for a consolidation and sortation area and the flexibility afforded by a warehouse management system. In addition, we recognize that the different order-picking methods require either single or multiple pickers per order, include single or multiple orders, and operate in single or multiple time periods. This affects the solution chosen and how it works in the warehouse.
Made to order
By reviewing data in detail, taking into consideration customer and shipping requirements, and choosing the right tools for the job, my group and I have been able to develop an effective, efficient supply chain system that meets customer requirements. In the end, we decided to use discrete order picking in our storerooms and zone-batch picking in our distribution centers. We also employ a combination of picker-to-part solution for large items and small, slow-moving items and part-to-picker methods for small, fast-moving items.
This may all change one day, and I plan to keep up with the latest supply chain tools so I can respond accordingly. I never want to look at the work ahead and see only a bunch of nails.
Gary A. Smith, CFPIM, CUSEC, is vice president of the division of supply logistics for New York City Transit. He may be contacted at firstname.lastname@example.org.
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