If a very narrow aisle (VNA) storage system is failing to reach optimum levels of efficiency the user’s first reaction is, generally, to assume that the trucks are underperforming. In most instances, however, this is not the case: more often than not the fault does not lie with the equipment but the surface it is operating on.
“The floor is the point at which the warehouse building and the truck interact and quite simply, a poor floor will result in poor VNA performance,” says Steve Richmond, general manager of Jungheinrich UK Ltd’s Systems & Projects Division.
Steve believes that the design, specification and final finish of the warehouse floor are absolutely critical to the optimised operation of VNA trucks. And, he contends, with truck manufacturers pushing the physical design of the equipment close to maximum efficiency, the performance of the floor will come under ever-greater scrutiny.
“You can invest in the best forklift trucks and materials handling equipment on the market, but if your warehouse floor resembles a ploughed field, the trucks will never be able to operate at their top speeds or optimum efficiency - think of it as driving a Ferrari down a cobbled street,” he says.
Whether faced with a new building where the floor has been laid to a particular specification or an existing site that is to be modified to accommodate a VNA application, a warehouse’s floor will present different challenges – although, generally, most problems occur within older buildings.
When installing VNA systems, the responsibility for specifying the level of the floor finish required lies with the truck manufacturer and there are accepted industry standards that lay down the specification, which the flooring should meet. The responsibility for achieving this specification lies with the flooring contractor. The relationship between the flooring contractor and the materials handling supplier is therefore critical and so, to ensure that everyone is working towards the same goal, a floor survey is always highly recommended. The survey will highlight any remedial works that might be required – as well as the extent of the works and should be used as a basis for all parties to assess the condition of the surface and its likely impact on the operation of VNA equipment.
From the outset, it is important to realise that floor flatness and floor level are two different things and their respective effects on the operation of a truck are totally different. According to TR34, the Technical report from the Concrete Society, flatness relates to the ‘bumpiness’ of the floor and general stability in operation of the truck. Floor level relates to the building as a whole and has to be right to ensure that both static and mobile equipment can perform satisfactorily together.
“Effects from the floor, can cause trucks to move from side to side or in a front to back ‘nodding’ motion as they travel along the length of the aisle. In some scenarios the movement of the trucks may be so significant that there is a potential for them to come into contact with the rack structure,” comments Steve.
“Meanwhile,” he adds, “even relatively small differences in the floor level within a racking aisle can have a significant impact when the truck is operating at heights often in excess of 15 metres. The higher the mast height, the more pronounced the ‘lean’ from uneven floors and the greater the potential problem.”
Whilst it is clear that there a number of important factors to be taken into account in this area, the good news is that anyone considering a VNA system should not be put off by the condition of their warehouse floor: in most cases, solutions are available to ensure that the floor can be made fit for purpose, as Steve explains: “Options include full aisle grinding, or local grinding where problematic areas are easy to identify. But, it is crucial that you engage a company that is competent in all aspects of the solution - from the initial survey to implementing the works,” he says.
Of course, just as the floor impacts on the capabilities of the truck, the truck will impact on the condition of the floor. In new buildings cracks often appear in the floor as a result of natural shrinkage of the concrete during the drying out process. However these cracks will worsen over time as heavy trucks run over them. In addition, the location of floor joints can affect the operation - although in new buildings these can often be designed into the system if the truck manufacturer is consulted at an early enough stage in the process. Needless to say, as a floor deteriorates, the performance of the materials handling equipment working on it may also suffer.
“Because the floor forms the platform for the materials handling operation and is, therefore, critical to the smooth running of the process, it is often difficult to understand why floor maintenance is sometimes overlooked within a warehouse,” says Steve. “Jungheinrich advises all clients to establish a planned programme of floor maintenance and to adhere to it.”
He continues: “Some warehouse operators specify a coating for their floors. A wide variety of products are available so choosing the coating that’s right for your facility can be 26difficult. Apart from cosmetically enhancing a store, a floor coating will – to a degree - prevent dust build-up. But coated floors can also bring about a build up of static, which can, in turn, lead to forklift problems - especially with electrical and electronic components. There are a number of ways to combat this effect, such as fitting ‘anti static’ discharge devices to the trucks, but it is always advisable to discuss all aspects of the floor with the truck manufacturer before making a decision on the solution that best suits your company’s needs.”
The construction method used when laying a floor will also have an impact on a VNA system – particularly where wire guidance systems are installed into the floor to guide narrow aisle trucks within the aisles. Where high levels of steel are incorporated into the design of the floor it is possible that the signal from the guidance system may be affected and this should be considered at the early stages of the design process.
“In summary,” says Steve, “VNA systems can offer significant improvements in performance and efficiency of a warehouse or distribution operation. However, because the warehouse floor can have such a significant impact on the operation of the trucks and indeed the overall facility, it is important to assess the design of the floor at the early stages so that the operational design of the system can be optimised. But, it should also be remembered, that if a survey shows that a floor is not suited for its proposed use there are a host of options available to upgrade the surface in order to achieve the necessary tolerances.”Steve Richmond
With an engineering background, Steve Richmond is general manager of the Systems & Projects Division of Jungheinrich UK Ltd. This specialist division within Jungheinrich covers a diverse range of products and services including VNA (Very Narrow Aisle) trucks, racking and storage systems as well as fully integrated turnkey materials handling projects.Jungheinrich UK Ltd
Jungheinrich UK Ltd offers pallet trucks, stackers, counterbalance trucks, reach trucks, order pickers, very narrow aisle and stacker cranes in more than 600 truck variants. As well as this, Jungheinrich provide an extensive aftersales support network, rental and financial services, racking systems and warehouse planning. The company is a division of the German-owned Jungheinrich Group, which has manufacturing facilities worldwide.www.jungheinrich.co.uk