Drive-In Racking provides the largest possible densities of storage with the lowest selectivity. It is therefore perfect for a very high turnover items that moves on a “pallet in pallet out” base. Racking is a sequence of tunnels to keep the rack with rails on either side. A tunnel drive looks somewhat like a multi-level bakery cart, only a Drive In tunnel is multiple pallets in depth at any level. Lift trucks can drive into any given tunnel, to retrieve or put away pallets.
- High density racking system, with virtually unlimited depth.
- No specialized fork lift trucks needed.
- Racking is less expensive than dynamic storage solutions (push-back / pallet flow).
- Level storage medium – no concerns about height restrictions as with sloping systems.
- LIFO – if stock rotation is an issue, you need to ensure that tunnels are being fully emptied before replenishing.
- Significant reduction in pick slots, as there are fewer aisles and each tunnel can store only a single SKU, from floor to ceiling- so e.g. in a 4 level system, there are 4 times fewer pick slots on any aisle vs. other systems. Plus, there are added slots lost vs. selective, since there are fewer aisles in a given floor area..
- Typically, observed capacity utilization is lower than for other systems, around 60%-70% is not uncommon.
- Drive In systems have more “sway” or lateral movement than other systems since there are no beams or cross ties between the front and middle frames. Drive-Ins are also the most prone to lift truck abuse, since the trucks drive in and out of each tunnel. Therefore, quality engineering and robust manufacturing are both critical to a successful installation.
Over Single Selective Racking
The level of improvement depends on the depth of the drive in. In theory, the deeper the drive in, the greater the improvement. But, proportionate storage improvements will only be realized if capacity utilization is at least as high as in selective racking. That said, for a 4 deep back to back system, the improvement over selective is as follows:
- Floor space savings of 35-40%
- Storage capacity increases of over 50%