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Combine storage types for better space utilization, productivity, and safety
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(Previously published in Material Handling Management- www.MHMonline.com)
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Many companies take vanilla, unimaginative approach to selecting storage equipment. Â Quick decisions are made without an analytical approach, and distribution centers are filled with basic pallet rack and perhaps some bin shelving. Â If some analysis is done to determine appropriate choices of storage equipment types for various groups of products, then they often locate the different types in distinct areas of the DC. Â For broken-case picking, bin shelving might be positioned in one area of the pick area, case flow in another, and storage drawers in yet another. Â Select rack might be in one area of pallet storage, pallet flow in another, and push-back or drive-in rack in a third area.
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While on the surface this may seem to make sense, there is often a lost opportunity to better utilize the cube space in the DC, which would reduce the square footage requirement and the related cost of building or leasing a facility. Â Also, there is a lost opportunity to reduce travel, labor costs, and even alleviate safety concerns. Â Consider some of the following examples of combining storage types when determining how to design your distribution center.
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Racking options above case flow rack
Often case flow rack is in its own corner of the world within the warehouse and the space above is not utilized. Â Also the case flow rack sections are compressed together and replenishing the case flow requires a fair number of employees with significant travel and the hand-off of replenishment product that has been transferred to pallet rack. Â The alternatives presented below utilize the overhead space but keep lift truck traffic out of the pick aisles.
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One alternative is to position case flow underneath the push-back rack. Â The case flow can be built into the push-back rack structure. Â Not only will you utilize space more effectively, but now replenishment can be a one-step process within the same aisle with much less labor required. Â Space utilization in this scenario can be enhanced even further. Â With additional structural support, the push-back rack can extend out over the pick aisle, gaining additional storage capacity.
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Similar to the push-back over case flow scenario above, case flow can be installed within a double-deep pallet rack system with a double-deep Reach Truck selecting and locating pallets above the case flow from the replenishment aisle. Â The pick-aisle side of the double-deep rack can have some protection added to prevent accidental falling of product in the pick aisle. Â This is normally a less expensive design than the push-back option, although there are some trade-offs.
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Push back over pallet flow
In a case-pick operation, some of your fastest movers are well-suited to be picked from a pallet flow rack. Â If your picking can be limited to the floor level, install push-back rack over the pallet flow. Â This will allow fast replenishment, and once again, lift truck activity is kept out of the pick aisle.
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Bin shelving over storage drawers
Storage drawers with dividers within each drawer are a good application for very small parts and better utilize space than the normal bin shelving alternative. Â However, typical storage drawer units are only chest high, and the space above is not utilized. Â To overcome this limitation, position a couple of levels of bin shelving on top of the storage drawer units to store additional product. Â This will reduce your requirement for other bin shelving in your facility.
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Bins under wire decking
Similar to how case flow is normally positioned in a warehouse, bin shelving often is in its own area with all the space above typical 7' high bin shelving unutilized. Â Bin shelving can be positioned at the bottom level of the pallet rack. Â However, bin shelving is only 24"-36" deep with an 8"-12" spacer between rows. Â Wire decking over the bin shelving in many cases might prove to be the best use of space. Â The wire decking could be installed with back-to-back 30"-36" uprights or with one single deep 48"-60" upright. Â The positions over the bin shelving could be used for reserved storage of SKUs located in the bin shelving or as pick locations for slow-moving products that require more cube than the items in bin shelving.
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Wire decking within pallet rack
In many DCs, managers will state that they are out of room and need more space and rack to put additional pallets of product. Â But after closer examination, a considerable percentage of pallet locations may be discovered to be only partially full with significant underutilization of space within pallet positions (honeycombing loss). Â A number of pallet positions could be subdivided into additional levels with wire decking used to support half-pallets or cases stacked directly on the wire decking. Â At one client's DC, 25% additional locations are being created by adding wire decking to store products that take up less cube than a half of a normal pallet.
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Multifloor picking on mezzanines with pallet flow or case flow
The best situation to be in is to be able to have picking on the floor level. Â However because of the large number of SKUs within many distribution centers, the number of pick faces required dictate picking from multiple levels. Â Two- or three-level mezzanines with picking to conveyor from case flow rack or pallet flow rack can be an efficient solution. Â To either side of this pick area can be additional pallet flow (or push-back or drive-in) for reserve pallets, depending on the number of apllets of each SKU normally stored in reserve.
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