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Frozen Storage Systems: Automatic or Manual?

13.06.2014

The requirements regarding the temperature-controlled storage of foodstuffs or medical products and the like are high: Uninterrupted cooling chain, minimized throughput times, optimized processes and minimal error rates. And all this in extreme working conditions: Temperatures in frozen storage warehouses are usually minus 18 degrees Celsius and lower. This puts great strain on the staff. At the same time, energy costs are rising sharply.

More and more companies are therefore deciding to automate their intralogistics. But what are the advantages of an automatic frozen storage system compared to a conventional manually operated one?

Business in frozen products is booming: According to the German Frozen Food Federation, last year the per-capita consumption of frozen products in Germany amounted to 41 kilograms. This represents an almost two-fold increase over the past 20 years. In total, 3.32 million tons of frozen food were sold in Germany in 2012. In view of such huge amounts, efficient processes are required along the entire supply chain – and the same goes for the field of intralogistics. In this context, many operators of frozen storage systems are faced with the task of weighing up the benefits of automatic storage against those of a manual system.

The first question arising in this context is concerned with the costs involved. »Automated storage systems are usually seen as initially more expensive and complex than manually operated ones,« says Frank Heptner, refrigeration specialist at viastore systems. »This is no different when it comes to cold and frozen storage systems.« At least the initial acquisition costs confirm this fallacy: They are higher than with a manual warehouse. The reason for this is the special technical equipment that is required in order to reliably operate an automatic refrigerated warehouse.

Technical equipment must withstand extreme cold

Generally, an automated storage/retrieval system is more expensive to set up than a manual system. This is due to the required equipment, such as storage/retrieval machines (SRM) and the conveyor system. In addition, in a temperature-controlled warehouse all the components, drives and controllers must be suitable for use at temperatures down to minus 40 degrees Celsius – refrigeration specialist viastore has even built warehouses for temperatures as low as minus 42 degrees. Components such as photo cells and sensors need to be heated so that they do not fog up in temperature transition areas. Control cabinets must also be heated or, if possible, be placed outside of the refrigerated zone. Moreover, suitable oils and lubricants are required, which have an optimum viscosity even at low temperatures to ensure proper function. All this means higher expenditure: »The investment costs for the entire logistics facilities can be about 80 percent higher for a temperature-controlled automatic system than for a manual warehouse,« reckons Frank Heptner.

Higher acquisition costs, but significantly cheaper to operate

However, this compares with significantly lower operating costs. In a refrigerated warehouse it is especially the high – and rapidly increasing – energy costs that mount up. After all, the required temperature must be maintained throughout the year. To increase the energy efficiency, the refrigeration loss must be as low as possible. Most of the cold in a frozen storage system is lost through the roof. Therefore, the key to reducing energy costs is to keep the horizontal storage area down to a minimum.

Here the automatic warehouse offers a clear advantage: While the rack height is limited to about 12 to 14 meters in manually operated systems due to the lifting height of forklifts, automated storage/retrieval systems make much more efficient and denser use of the existing space with racks up to 45 meters high and multiple deep storage. »A manual warehouse with 6,000 pallet storage locations requires nearly 4,000 square meters of space,« explains Heptner. »An automatic system with the same number of storage locations gets by with only 2,000 square meters. This means that the cost of cooling is about one third lower.« In addition, the warehouse operator saves costs arising from the smaller building lot.

Automatic processes in the refrigerated zone protect the employees

Another aspect in favor of automatic storage systems is that no human work is needed in refrigerated zones. Working at temperatures well below zero is a substantial strain for the employees that can only be reduced by the use of special auxiliary equipment, such as trucks with heated driver cabs. In turn, such equipment may limit the range of action of the employee and cause high investment and operating costs. The maximum working time in a refrigerated area is limited to 45 minutes at a time, which leads to a loss of warehouse performance. Due to the extreme operating conditions, staff turnover is particularly high in frozen storage systems. To find employees willing to carry out this unpleasant work long term is difficult.

Here too, the automatic storage system can bring to bear its advantages. All operations in the refrigerated zone run automatically, ideally not only the transport as well as the storage and retrieval processes, but order picking as well. This ensures an uninterrupted cooling chain and the staff is not exposed to the low temperatures. Operating an automated warehouse also requires far fewer employees, which leads to a significant reduction in personnel costs. »Where three operators are needed in a manually operated system, two of them being in the refrigerated zone, only one employee who is outside this area is necessary in an automatic warehouse,« explains Heptner. »The technology takes over the unpleasant work and the remaining workplaces are much more agreeable, more ergonomic and less stressful.«

Faster and more reliable thanks to technology that is suitable for frozen environments

As for reliability, manual warehouses have clear disadvantages: Even the best operator makes a mistake sooner or later – especially in such conditions. This can quickly affect the performance of the system and the quality of the stored goods. Every now and then a product gets left behind in the warehouse, sometimes the expiry dates of stored food are not read properly and once in a while a pallet ends up in the wrong place. The temperature-controlled storage system is especially error-prone when operated manually: The warehouse staff is under physical stress due to the cold. Moreover, labels on packaging and pallets can ice over and thus be illegible. All this inevitably leads to higher inventory levels because there is always a degree of uncertainty about the current inventory and expired goods may have to be disposed of. At the end it is the warehouse and distribution performance that is suffering – and thus customer satisfaction.

No matter whether manual or automatic storage: A suitable warehouse management system (WMS) with all the regular functions, validations and certifications is a basic requirement in both types of warehouse. The WMS allows for consistent traceability and documentation of goods along the entire supply chain. In the food or pharmaceutical industries in particular, this is an important factor for ensuring high product quality. Furthermore, a professional WMS ensures inventory transparency so that stocks can be kept to a minimum. This saves costs.

The WMS controls all the processes in an automated warehouse and in many manual systems – however, in automated systems these processes are carried out automatically by the storage/retrieval and conveyor technology. This technique relies neither on the optical identification of goods or label texts, nor is it affected by the low temperatures. This allows a higher throughput with minimal error rates. The result is higher quality product at lower cost. The operator of a refrigerated warehouse can pass both of these on to his customers. This in turn has a positive effect on the company’s image and pays off in the end.

So a direct comparison shows that although the investment costs for an automatic frozen storage system are higher than for a manually operated one, the system will pay for itself within a short time due to lower operating costs. »The key advantage is the attainable warehouse efficiency,« says viastore expert Heptner: »Especially for larger systems, automation will pay off very quickly, often even within the first year. Automatic refrigerated warehouses also offer significant advantages in terms of availability and working conditions.« These make themselves felt even more strongly when working in several shifts: »The additional costs associated with shift work in a refrigerated warehouse with automatic storage are not even half as high as in manual systems,« explains Heptner. The reasons for this are lower maintenance costs and lower personnel requirements.



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