Automated vertical lift modules (VLMs) were developed in the 1980’s specifically for small to medium parts storage rather than the lighter commercial applications of the vertical carousel. This type of automated goods-to-man storage and retrieval system consists of fully enclosed towers with 2 column of stacked trays. At the press of a button, the elevator with extractor fingers which runs down the middle of the towers swings into action to locate the requested tray and deliver it to the operator through a pick window. While this basic structure has remained largely unchanged since it was first developed, much else has, increasing its appeal as a space saving, high-density storage system.
Firstly, height. Today’s VLM extends to over 20metres, more than twice the first units, ensuring the optimal use of available space. Modular in construction, it can be configured to meet different requirements. It can extend over multiple floors with access openings. The height as well as the number of access windows can be adjusted before and after construction.
As for the weight, it can handle over 1,000 kg per tray, more than four times its predecessors. By providing more capacity per tray, storage cost per square metre can be reduced. Trays of different sizes with different capacities can be accommodated within a single VLM for improved functionality. Click here to download the FREE VLM Whitepaper.
The system is also big on ergonomics. The physical height at which the tray is delivered through a pick window can be personalized by the operator. Mechanical arms can also be added to facilitate handling of heavier items. Some models also provide a tilting mechanism which allows the output table to be tilted to reduce the reaching depth for easy retrieval and parts overview. By reducing reaching, lifting, stretching and bending, the VLM can reduce the potential for work related injuries.
Possibly the biggest change is in the control and software which allows operator to manage their inventory more intelligently. It is now possible to:
accommodate goods below opening height as products on each tray are scanned before being putaway in an appropriate location
store goods into ABC categories, with A representing fast moving good stored nearer to access opening and C the least, and prioritize access times for stored goods
program different travel speeds for different trays to ensure safe handling of stored goods
improve performance through parallel, time-delayed tray movements – while goods are being removed from the first tray, the next tray is already moving towards the operator
ensure optimal usage of the system through defragmentation – compressing the storage space and re-localizing the stored trays so that more space can be created
prevent over loading through constant monitoring of tray and unit load
have visual display of the system with overview of the filled and empty trays
With the recent advancements, VLMs, once used primarily for spares storage in maintenance repair and tool and die operations, can now be found in diverse applications, including manufacturing, assembly, distribution, retail and warehouse operations, serving as the standalone storage system or part of a fully integrated solution.