By Eamonn Ryan
For companies to optimise storage space, a racking system is the logical way to go. Over the last few years, technology has progressed rapidly towards automation and semi-automation. However, South Africa’s twin challenges of unemployment and skills shortages mean the full benefit of automation is not being realised.
Training of staff is consequently extremely important, while managers need to regularly visit their warehouse to check that racking maintenance is being performed. Overseas, this is mandatory. In South Africa, periodic checks and maintenance – whether internal checking or external companies – are commonly neglected. This should be done by a competent person to identify any damage or overloading which can then be rectified before rack collapses occur. The latter can result in millions of rands in losses or even death.
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In recent years, especially in freezer stores, freezer heights have been increasing and racking is consequently required to handle heavier loads. A common planning mistake is failure to provide sufficient flexibility – when a company wants a seven-metre-high store, they typically plan for seven metres when in fact they should consider racking of at least 10 metres high. Any commercial store must accommodate for growth and future diversification in products that may have differing weights.
Most racking suppliers offer the design of the racking and the layout of the store in their services and some also offer this through a complete computerised or simulated system based on the gathered information where the most appropriate designs are revealed.
The choice of warehouse racking and shelving
James Cunningham, MD of Barpro Storage SA, explains that the racking type chosen can depend on warehouse type: freezer, chiller or ambient? Freezers and chillers are expensive to build and have unique operating requirements. “Other factors include fire regulations and the possibility of in-rack sprinklers. The nature of product to be stored is obviously critical. Are there multiple stock keeping units (SKUs)? Must stock be rotated religiously? Is product palletised? Will case picking occur before dispatch? As a cold store manager, I remember having to pack containers with boxed frozen fish in reverse date of manufacture sequence, ie the oldest stock had to be stowed next to the doors. As it was practically impossible to do this from a block stacked freezer without hypothermia and superficial frostbite, mobile racking – novel then – was retrofitted. Where there is a case picking requirement in ambient warehousing, fixed selective rack, or APR is the normal choice. In freezers, expensive space and product temperature maintenance considerations dictate such solutions as mobiles combined with in-freezer mezzanine picking floors.”
The racking decision must never be an afterthought to be finalised once warehouse construction has begun. “I have seen too many warehouses where an additional 500mm in the height could have added 20% to storage capacity or moving an interior wall by the same distance could have achieved the same result. Storage capacity and surrounding requirements,” Cunningham advises, “should drive warehouse design, not the other way round.”
Certain types of racking are easier to retrofit than others. Barpro Storage has successfully retrofitted mobile racking, he says, but typically the existing floor must be replaced, rails trenched into it or an overlay slab laid. Depending on size a room can be recommissioned in as little as five weeks.
“Although racking spare parts can be sourced when required, I advise clients to keep some on site because there can be long lead times due to the small volumes involved. When installing the original system buy extra components but store them under cover,” says Cunningham.
He doesn’t encourage customers to do their own repairs. Barpro has branches in Gauteng, Cape Town and Durban to assist customers with spares and maintenance of mobile bases at their sites. Barpro doesn’t do actual rack repairs but can suggest contractors. “Occasionally customers want to do their own maintenance, but generally that’s a mistake. There tends to be insufficient, if any, maintenance of racking taking place in warehouses. The amount of education on racking safety is poor among on-site personnel. To cater to this need, Barpro offers rack safety training courses to try and educate on-site staff as to what is dangerous, and what they should be looking for in their racks.”
Companies do not have a good record of regularly checking for and repairing racking damage, especially in freezer stores, so damage can remain unnoticed for a considerable length of time. At the extreme, a collapse can occur. “At the moment, the on-site level of understanding of racking and checking and maintenance is poor, and Barpro, in addition to its training, is trying to change that. Barpro has a Storage Equipment Manufacturers Association (SEMA)-approved racking inspector working for it, who inspects customers’ racking as requested.
He notes there are ‘good’ and ‘bad’ collapses. A ‘good’ collapse is where pallets come loose, falling to the floor and across the aisle but confined to one, two or maybe three bays. In contrast, a ‘bad’ collapse occurs when the whole rack swings across, hitting the next one and causing a domino effect.
Cunningham, who has been in the business for over 25 years, notes that the same problem existed in Britain until about 20 years ago. It was then covered by the Health and Safety Act in Britain, making warehouse operators responsible for racking checks on a regular basis. “In South Africa, notwithstanding some notable exceptions, I would say 80 to 90% of warehouses or racking users do not do regular checks and do not know what to look for.”
Barpro is devoting a lot of energy at the moment to promoting rack safety and inspections on behalf of customers. “As the need for storage capacity rises, cold store heights have increased. Simply put, the higher the racking the greater the need for rack safety.
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“Another issue is that pallets themselves are becoming a risk. When you place a pallet at 3m and it breaks and falls – it’s an issue but not necessarily a huge one. However, if a pallet breaks at 12m and comes down, that’s a big issue. We’re finding that pallet construction is getting flimsier, with more so-called disposable pallets in circulation. We’re also seeing that some pallets are being constructed slightly smaller so as to fit additional pallets into containers. However, it cuts the safety margin when storing the pallets in racking – because while pallets are getting smaller, the racking is not. The manufacturers and buyers of those pallets need to be cognisant of the racking when they reduce size.”
Different types of racking: fixed, mobile and others
Cunningham lists two basic types of racking: individual access racking and high-density racking. Racking users either want immediate individual access to a pallet or maximum pallet density. However, there’s less of the latter today as storage requirements are shifting towards individual access.
Individual access racking types include automated storage and retrieval system (ASRS) crane systems, very narrow aisle racking systems, flexi reach truck systems, normal reach truck systems, static and mobile racking. High density systems include drive-in, shuttle and push back.
Automated racking systems tend to depend on a country’s demographics, explains Cunningham. “It started in Japan where there has long been insufficient labour. The concept spread to America, Australia and Europe where labour is costly. “The downside is that the equipment is extremely expensive and requires a different type of technician to look after it. In South Africa currently, the trend towards full automation has eased.
“Semi automation is what Barpro achieves with mobile racking, which is our specialisation. Mobiles still have manual input, but the mobiles can be moved automatically, controlled by the warehouse management system. Mobile racking has been described as the sweet spot in the move towards automation. With immediate individual pallet access, the pallet itself doesn’t move. A warehouse management system is particularly well adapted to this scenario, but less so where the pallet can change position, such as in shuttle or drive in racking systems.”
As to which racking system is appropriate, Cunningham says: “It’s a matter of scale. If a business has a store 4m high and needs some racking, a mobile system is probably not the answer. Where a warehouse is 12m high with a need to get in as many pallets as possible, then mobiles demand consideration. It’s a matter of how many pallets a business wants to get into the store. We have put in mobiles at two-pallet high applications, because the warehouse manager was happy to double what was previously possible and it was financially viable at the time.”
One has to bear in mind how far the racking industry has progressed. “In my first job at an old-style (more than 30 years ago) freezer store, when racking was installed we effectively doubled our productivity. Then with a warehouse management system we doubled it again. Thereafter, in a freezer store if fixed selective racking is replaced with mobiles, irrespective of narrow or normal reach truck aisles, storage capacities can again just about double.”
The pay-back on mobile racking capex varies entirely on circumstances. “We had an instance where a poultry company wanted to build a new warehouse. However, their existing facility, built 10 years earlier, had mobile rails in the cold store floor. This had been overlooked. We showed them that by utilising the rails for a mobile system they could achieve exactly the same additional storage as the proposed new facility. The retrofit paid for itself in under a year.
“Consequently, we always suggest to customers who are building freezer or chilled stores to put mobile rails in the floor, even if they install static racking to start with. It’s much more difficult to install rails later when the need for storage capacity increases,” says Cunningham.
Setups, height and weight factors
If a customer’s operation needs require a higher warehousing capacity, there are a number of options that can be applied – standard racking can be re-designed to handle any pallet weight, for instance by the addition of stronger beams.
Standard sizing of frames is the norm, but they can also be tailor-made for the customer utilising odd-shaped pallets, for example 1500mm x 1200mm. Everything is customisable as the product is generally modular in nature.
Facility layout and racking design is predicated on the customer’s predetermined strategy. The elements that should be considered from the outset include: the potential for future expansion or upgrade, the dimensions of the property and consequent spaces for storage, the equipment to be used and flow of traffic.
Over the past years, most companies have adapted their storage facilities to higher racking and today it is not uncommon to see installations anywhere from 7m–14m high, and designs catering to a maximum pallet weight or tonnage per bay.
The racking itself can consist of many variations in frame size and beam dimension, partly depending on how many pallets are loaded per rack compartment. Some applications have two pallets per pair of beams, with either the short or long side of the pallet facing the access aisle. Gross pallet weight is another consideration as well as the number of pallet levels in the height. Generally, the higher the racking the greater the loads imposed on the frames. Open bay widths should increase with height to widen gaps between the pallets. But increasing the number of pallet levels (within reason) also reduces the freezer footprint. ‘Higher’ freezer stores tend to have a lower capital cost per pallet position created than lower ones with fewer pallet level.
Rack frames include bracing to keep the rack uprights at the right distance apart. Different bracing patterns can change the loading capacity of rack frames but such design aspects are now increasingly computer generated. As a general rule though, a rack user should never change bracing patterns or beam levels without first speaking to the company that supplied or manufactured the racking.
There is also a structural difference between mobile and static options. On mobiles they have to be able to work with dynamic loading (which is that they are moving), whereas the fixed racking stays in one place so the design criteria on mobile racking needs to be more robust that the static solutions.
References:
- Cold Link Africa, July 2021
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