Comparing compact storage systems

December 9, 2019

When it comes to choosing industrial racks for pallet storage, two main types are available: standard and compact systems. Depending on the characteristics of both your goods and the warehouse's operations, priority will be given to accessibility to each pallet over space usage. If your aim is the latter, you achieve greater storage capacity with high-density storage systems.

But, within the compact storage category, you will find a series of subsystems with differentiating characteristics. The main compact systems are:

So, what are the main criteria to think about when picking one or another?

Channel depth differs depending on the high-density storage system
Channel depth differs depending on the high-density storage system

Criteria for comparing different compact storage systems

  • Number of SKUs: generally speaking, compact systems are ideal when many pallets of the same SKU are involved.
  • Lane or channel depth: each stores pallets from a single SKU, so the capacity will depend on the storage depth allowed and the pallets per SKU.
  • Merchandise rotation: your rotation levels (A-B-C) will also help define which rack system is most suited to each type of goods.
  • FIFO or LIFO flows: high-density systems usually work with FIFO (first in, first out), but there are exceptions.
  • Productivity: although these are usually less flexible systems than selective pallet racks, you can compare them on the agility and operability they allow.
  • Safety level at the time of operation.
  • Initial investment required and estimated ROI.

Comparing compact storage systems

Let's take a look at the characteristics of the major compact systems by looking at each individual criterion above:

Depending on the number of permissible SKUs

The number of pallets per SKU will determine the suitability of one system or another. Some systems accommodate more SKU variety than others.

Number of SKUs per system
Drive-in rackingPush-back racksPallet ShuttleMovirack mobile pallet racks,Flow racks
Low, each lane only holds one SKUMedium/High, each channel holds one SKU, but if there are five levels in a bay. So, this number multiplies by fiveMedium, each channel holds one SKU, but should be at least 8 pallets deepHigh, as it gives direct access to SKUs (once the aisle is open)Medium/High, each channel holds one SKU, but if there are five levels in a bay, this number multiplies by five

Systems according to the channel or lane depth

Each lane of the racks houses pallets of the same SKU. So, the capacity is determined by how deep the channels can get.

Channel depth per system
Drive-in rackingPush-back racksPallet ShuttleMovirack mobile pallet rackingFlow racks
Medium or low, should not exceed 8/10 pallets deepLow, depends on whether trolleys or rollers are used, but may be limited to 4 pallets deepHigh, holds more than 40 pallets deepIt’s halfway between compact and standard systems, so this system is usually single depthHigh, deep stores more than 20 m of pallets

Racks recommended in relation to the rotation of goods

There are certain patterns that show some systems are more suitable for storing high rotation (A) goods, or medium rotation (B) or even low rotation (C) ones. As a guide, you can make a distinction between:

Recommended rotation type per system
Drive-in rackingPush-back rackingPallet ShuttleMovirack mobile pallet racksFlow racks
High rotation (A)Medium (B) and high (A)High rotation (A)Medium (B) and low rotation (C)High rotation (A)

Comparison as per compatibility with FIFO or LIFO flows

The sequence which the flows of goods follows and the movement of stock are fundamental issues in defining which type of system is compatible with your way of operating a warehouse. With that in mind, your options include:

Operate with either a FIFO or LIFO system by system
Drive-in rackingPush-back racksPallet ShuttleMovirack mobile pallet rackingFlow racks
FIFO: drive-in LIFO: drive-throughLIFOIt lets you to operate with FIFO and LIFO (more common with LIFO)It lets you to operate with FIFO and LIFOFIFO

Systems compared on productivity potential

In every warehouse, there is a delicate balance between the storage capacity and the operability of your installation. In the case of high-density racks, the channels’ depth, number and type of operations to be performed define how productive each system is:

Productivity per system
Drive-in racksPush-backPallet ShuttleMovirack mobile racksFlow racks
Low, mainly because the forklift must be inserted into the channelHigh, the maneuver is direct since the pallet is taken from the first positionMedium/high, if you need to change the shuttle’s levelMedium/low, because you must open aisles every time you want to access a SKU. It will depend on the management of locationsHigh, the forklifts must not move within the channels

Comparison of safety operations

Safety is another important issue when choosing one system or another. The risk of accidents will be limited–more or less–by the racking’s characteristics and operations involved in using it:

Safety system
Drive-in racksPush-backPallet ShuttleMovirack mobile racksFlow racks
Low, inserting the machines into the channels increases the risk of impactsHighHighHigh, by including automatic detection and shutdown systemsHigh

Systems compared on profitability and ROI

To evaluate the economic viability of one solution or another, take not only the initial investment into account, but also the impact that the system will have on operating costs and the estimated return on investment (ROI). For example, it is common for state-of-the-art solutions to require a higher initial investment. In return, the increase in productivity and the associated cost reduction mean that the return on investment is shorter in the long run.

Drive-in racksPush-backPallet ShuttleMovirack mobile pallet racksFlow racks
The initial investment is lower but the ROI is shorter in the long term. Although racking is the cheapest, equipment and operators you need must be also consideredThe initial investment is higher, but requires less handling equipment than drive-in racksThe investment is average in size, as it entails purchasing automated systems. But it provides high performanceThe ROI is medium-term.
An average-sized initial investment. Considerable storage space is saved
The investment is recovered in the medium term.
The initial investment is high. It works with less equipment but requires more storage space

Conclusion: What is right for my business?

However, before deciding between one type of compact rack or another, you should carry out a pre-calculation of the pallets that would be housed with each option, considering the available surface area in your warehouse and the handling equipment. If you would like one of our experts to give you some detailed advice, get in touch with us. We will help you find the solution that best suits your warehouse.