Pallet Racking

This can often be a perplexing question, with personal experience (or lack thereof), advertising, word-of -mouth recommendations from others (including salesmen!), and many other influences at work. For the sake of this article we will consider only unit-load storage – ie. palletised goods – although some of the comments will apply equally to bulk, cartons, small parts, etc. equally. Obviously the first major consideration is whether you will be making do with existing premises, or do you have the freedom to build a new facility from scratch? If the former, then you are clearly limited to working within the confines and limitations of such premises. With a new build you have the opportunity to plan it right from the start. Huge advantage. We will assume the latter, although the following will also apply to existing buildings within the limitations mentioned. The first obvious question is whether product is to be stored at ambient temperature, or chilled, or frozen? Other important considerations are type of product, product mix (number of different items, or SKUs), shelf-life or importance of stock rotation, susceptibility to damage, need for order picking of individual items and to what extent, and many others. How essential is it that you make optimum use of available space? And this refers to volume, not just square area. If you have very little product, and huge areas in which to store it, then the simplest solution is to just dump it on the floor. This of course is hugely wasteful and inefficient by any measure you apply. So the next step, almost invariably applicable, is to use racking of some kind. This is where analysis and application of the relevant data is required. Virtually every new facility is required to squeeze in as much product as possible for obvious reasons – and to meet this criterium there are multiple choices of ‘hi-density’ racking systems available on the market. How high should you make your building? Bearing mind when doing your financial sums that it is volume you need to consider, not just area, since this is what you’ll ultimately be paying for (very especially in the case of cold and freezer stores). Generally speaking, the higher the better, from a cost-per-pallet stored perspective. The following are some of the systems commonly considered: High Bay systems Many stores around the world will use hi-bay VNA (very narrow aisle) rack systems, which can be up to 30m or more tall. This is fairly efficient in terms of space utilisation, and moreover allows selective access to every individual pallet. However, flexibility is seriously compromised – especially when the racks are use as the support structure for the building, an increasingly popular application – and once built the system is restricted to only the specific size and weight of the loads it was originally designed for. Such systems are also costly, and involve lengthy construction times – and need very expensive specialised handling equipment, and a high level of automation to work really well. Medium High systems – ie. up to maximum 15metre high, and operable with free-ranging equipment such as Reach-trucks. These include: Double-deep racking Very popular in USA and Australia, this system is hardly ever used in South Africa, largely due to the specialised handling arrangements needed, the slow and unwieldy operation, and the fact that every second pallet is behind another one and thus inaccessible until having removed the front one. First-in, first-out (FIFO) is made far more difficult to achieve. Drive-in racking This is commonly used in South Africa for products where multiple pallets of the same product can be stored one behind the other in deep lanes on longitudinal rails instead of lateral beams, with little regard for selectivity or product rotation. Theoretically pretty efficient in terms of space utilisation, in practice drive-in racks are usually ‘honey-combed’ with empty pallet spaces in attempts to respect the need for product or batch rotation. Operation is usually slow and cumbersome with FLT drivers needing to negotiate their way down the narrow lanes, and rack and product damage is high. As above, FIFO is simply not possible. Radio Shuttle systems These are every similar in structural appearance to the above-mentioned, consisting of deep lanes in which to store the pallets on rails, but instead of FLTs needing to drive into the rack, this function is carried out by remotely controllable trolley-like shuttles which pick the pallet up and transports it as far back into the rack as possible. Huge advantages over Drive-in are that each level can be a different product, and that FIFO is easily achieved by inserting pallets in on one side and out on the other. ‘Honey-combing’ is avoided by programming the shuttle to ‘shuttle’ pallets forward in the system during downtime ready for extraction at the other end, so that replenishment can be effected without delay. Shuttle storage is incomparably faster in operation than Drive-in. Powered Mobile racking Here, conventional adjustable pallet racking is mounted onto electrically powered mobile bases which run on steel rails precision laid and embedded into the floor. The racks are moved laterally by local or remote command to open up an access aisle for the handling equipment only where and when needed. This obviates the need for multiple aisles, which are just wasted space when not being actually used. A vast advantage over others systems mentioned is the ability to access any single pallet individually at any time anywhere in the system. Moreover the systems remain flexible in terms of adjusting to suit changing needs, and can be used to store virtually any kind of product. Other Choices We have restricted ourselves to the foregoing main methods of rack storage, but those who are familiar with racking systems will be aware that there other options available such as push-back racking, gravity flow or ‘live’ racks, etc. These however tend to be highly specific in terms of application, can work at only limited heights, seriously restrict product rotation, and are very expensive both to