The initial trend in the technology of automated small-parts warehouses, away from storage and retrieval machines (SRMs) and toward shuttle systems, has been put into perspective in recent years. SRMs are still worthwhile pieces of equipment and, depending on requirements, can offer certain advantages. Recognizing those advantages is crucial when considering the particular application and must be included in the decision-making. Employing both technologies might even be sensible, depending on the system. In times of globally organized online commerce with increasing product diversity and high inventory turnover rates, warehouse operators require ever more flexible systems. Choosing the right warehousing technology always calls for an individual evaluation of the various storage parameters. In automated high bay warehouses, the actual throughput is playing an ever greater role. With shuttle systems, storage density and throughput rate complement each other, also in pallet storage. DAMBACH Lagersysteme’s many years of experience in storage and retrieval machines, materials handling technology, shuttles, and complex control structures has enabled it to develop the MULTIFLEX pallet shuttle system. MULTIFLEX stands for maximum flexibility and maximum throughput coupled with a high storage density.
Applications for Pallet SRMs
The potential applications are diverse and depend on warehouse capacity, capital outlay, throughput rates, and type of warehouse. For example, SRMs equipped with one COMPACT SHUTTLE operating in the storage lane are especially suitable for systems with a high storage density and low product diversity. Such solutions are popular for cold stores because of their good space utilization. SRMs with double-deep telescopic forks enable more direct access to products and a relatively high number of storage and retrieval operations. Such SRMs are now the favorite solution for high bay warehouses, regardless of whether they handle spare parts, foodstuffs or paper.
SRMs with single-deep telescopic forks and powerful drives ensure direct access to individual products and remarkable throughput. They are used in the dispatch buffers of mail-order warehouses, for example.
Proactive planning allows users to upgrade performance at a later date by adding further COMPACT SHUTTLEs or fitting telescopic forks to existing SRMs. Introducing a second SRM per aisle is also possible. Redundant access, and hence almost 100% availability, can be achieved with curve-going SRMs. So SRMs are much more flexible than is generally assumed and offer high security for investments.
Applications for Pallet Shuttle Systems
The MULTIFLEX pallet shuttle system combines high storage density with incredible throughput rates. For example, depending on the warehouse system, 250 storage and retrieval operations are easily possible every hour. In addition, the MULTIFLEX system requires a much smaller space for the same performance and storage capacity. The system consists of the perfectly synchronized interaction of three modules: CARRIER, COMPACT SHUTTLE, and LIFT. This concept separates the lifting, traveling, and storage axes. Another bonus is the scalability – further CARRIERs are easily integrated. Using the CARRIER-LIFT, it is possible to relocate CARRIERs on different levels, which reduces the volume of investment. The MULTIFLEX system renders the intermediate dispatch buffers of mail-order warehouses obsolete. In a compact MULTIFLEX warehouse, for example, it is possible to unload a complete articulated truck, a total of 34 pallets, in just 8 minutes. That is particularly useful for applications in drinks logistics. Owing to its modular design, the MULTIFLEX system is also suitable for existing buildings or warehouses with a complex layout.
Categorization
To achieve a better assessment of the different options, four warehouse systems – SRM with single-deep storage, with double-deep storage, with shuttle, and the pallet shuttle system (MULTIFLEX) – are shown below.
Total Cost of Ownership
When comparing the options, it is necessary to consider the capital outlay for buildings and systems, energy consumption, and the cost of upkeep. Various calculation models, e.g. price per storage position or price per pallet handled, can be employed to enable a direct comparison. To do this, we define a typical reference facility that is about 40 m high, with 12 levels and racking 80 m long. Three SRMs with double-deep storage are compared with one MULTIFLEX system with six-deep pallet storage having a similar throughput.
Capital outlay:
• SRM corresponds to MULTIFLEX
Space required:
• SRM: approx. 74 000 m³
• MULTIFLEX: approx. 61 000 m³
Energy consumption with energy recovery:
• SRM: approx. 0.36 kWh per double cycle
• MULTIFLEX: approx. 0.25 kWh per double cycle
Cost of upkeep:
• SRM corresponds to MULTIFLEX
Summary
Whether opting for storage and retrieval machines or a pallet shuttle system (MULTIFLEX), the right solution depends on the specific application. It can even be worthwhile to employ both systems in one warehouse. Therefore, these are not rival, instead complementary systems. Pallet shuttle systems offer throughput rates unknown in the past plus flexibility for high bay warehouses. The flexible maintenance concepts for MULTIFLEX systems, even during ongoing operations, represent further bonuses. Working as an independent partner to system integrators and general contractors worldwide, DAMBACH has already installed various MULTIFLEX systems – also in the harshest cold store conditions.
Authors:
Head of Control – Dirk Lorenz
Product Management – Dr. Benjamin Thumm