What a boring topic: what is the optimum pallet height? But if you take a closer look, it is quite exciting. Why is that? Because this topic has direct potential for cost and CO² savings.
This is most clearly illustrated by the example of a full truck: a standard dimension for a pallet height is CCG1 - 105cm including the pallet. Two of them stacked on top of each other are then 2.10m. A truck usually has a loading space height of at least 2.60m. So there would still be half a meter of "air". In other words, a truck fully loaded with CCG1 pallets transports 20% of "nothing".
The solution is obvious: simply build higher pallets. But this white paper explains why this is not so trivial, what the problems are, what developments there are in this area, and which approaches can still work.
Different standards, different heights, wasted space = great savings potential
Storage and logistics centers were and are planned based on various requirements. In addition to break pallets and picking locations, which are usually located in the lower areas of the shelves, there are various dimensions that are common nowadays and are actually also "standardized". Unfortunately, there is no one standard:
Pallets must fit on the shelf
This results in one of the fundamental problems in the optimization of pallet heights: not only the transport must be taken into account, but also the storage options.
Here is an example from one of our projects for the shelf height distribution in the high-bay warehouse of a new warehouse building for the food retail trade. This compartment distribution was made on the basis of a data analysis of the stock pallets:
The compartment heights are defined with the permissible height of the pallet to be stored. The physical shelf is then still higher than specified here by the excavation clearance, sprinkler clearance and tolerance, while the loading height of the pallet is 15cm (144mm to be precise) lower.
CCG1, CCG2, EUL - or simply 1,600mm?
Actually, the company has only allowed CCG1 and CCG2 in its Packaging Guidelines and, according to the delivery terms, benefits significantly when ordering full pallet multiples. Nevertheless, the non-standard height class 1,600mm accounts for a significant proportion of the total number of compartments. The data analysis also does not show such a clear focus on CCG1 heights, but still knows some intermediate levels, and the EUL heights, which are not permitted per se in the specific case, are also frequently encountered.
So there are other factors involved in the supply chain that make the real pallet heights very heterogeneous and also quite variable:
- Pallets with the maximum permissible weight often end up somewhere between CCG1 and CCG2
- Somewhat unstable articles often do not allow utilization of the full height
- Manual handling is not very ergonomic above 1.8m pallet height
- Transport with double-decker trucks prevents high pallets
- Existing (often quite old) bearing technology at the manufacturers defines the maximum height
- And last but not least the ordering system still has its problems to convert the demand into pallet multiples.
In the warehouse there are then still numerous pallets significantly below 1,200mm in height. These are mainly low pallets due to the ordering behavior ("layer pallets"), breakages of larger pallets and all kinds of "leftovers" from expired articles and long forgotten promotions.
Planning of new buildings
In the case of new buildings, there is no getting around a realistic consideration of the distribution of shelf heights. Under no circumstances can you design according to the specifications of the Packaging Guidelines, as in most cases there is a lack of practical feasibility. Even the representation of the actual heights does not lead to the goal, because in this way a whole series of grown structures and "lazy" compromises are automatically taken over into the new building. The issue of "increasing pallet heights for better cargo space utilization" can only be addressed by planning a sufficient number of high compartments.
A strategic consideration of the future pallet heights is therefore part of every new building. However, this requirement must be specifically pursued by the planner, because high compartments are unpopular with suppliers of material handling technology due to the higher costs and are also often cancelled by the project team when the budget hits the ceiling.
In the goods receiving area, it should be possible to process both EUL 2 and stacks of several pallets up to the total height of EUL 2 in new buildings.
Why not just convert it?
Older locations often have technical restrictions that could be eliminated by conversion - changing shelf heights in the wide-aisle warehouse, resolving isolated collisions on a conveyor system and the like. However, the effort required for this increases rapidly as soon as structural measures are necessary, for example on fire protection doors, if ceiling beams or intermediate platforms are in the way or sprinkler lines have to be laid on a large scale. In automatic high-bay warehouses, there are also changes to the controls, and in any case the statics of the racking compartments must be considered if free buckling lengths increase.
In practice, this means that in the majority of cases at older locations: EUL 2 pallets can only be stored in small numbers. A goods receipt of several stacked pallets with a total height of EUL 2 should not be a problem at first, but the racking compartments for EUL 1 may be missing if only CCG1 is expanded.
Conversion is therefore more of an emergency measure and cannot replace forward-looking planning from the outset.
Look not only at the shelf, but also at the conveyor system
If the racking "fits", the next step is the conveyor technology: Pallet conveyor technology is usually only designed for 1,000kg in the standard of material flow technology suppliers. On closer analysis, individual pallets (such as sugar) with a maximum of 1,140kg can be found in the trade. With an increasing pallet height, other articles may reach this weight limit.
Realism is also required here, the heavy pallets can only be avoided with difficulty, while a general dimensioning on heavy pallets again drives up the costs.
On the basis of forward-looking planning, however, the load cases can be described well and it can be checked for all areas of the warehouse whether it really has to be dimensioned for this or whether it can be solved by IT organizational measures.
Handling of higher pallets
Sandwich pallets are usually unstacked by industrial trucks in the goods receiving area. Industrial trucks with double lift are often used, so that at least pallets stacked in pairs can be unloaded quite efficiently and placed on a conveyor or set up in the area in one operation.
Outgoing pallets to the stores are limited to 1,800mm almost everywhere in retail (by operational specifications) - with the exception of "topping up" with light voluminous articles such as toilet paper or similar. In practice, higher pallets can of course also be found in a store, but these exceptions already lead to discussions today.
Very high pallets also tend to be unstable on the conveyor system, resulting in higher demands on the quality of the pallet and the securing of the column of goods. This may reduce the cost advantage during transport.
In principle, one approach would be to adapt the "applicable" standards on pallet heights to the circumstances and implement them. At the same time, however, communication between suppliers and retailers could also lead to a certain flexibility that leads to the desired goal. Of course, a quick change requires investments in (new) rack heights and possibly conveyor technology. However, if one considers that this can lead to cost and CO² savings more quickly, this is likely to be an issue that could pay for itself more quickly than is currently thought, since it is precisely the approaches that are not or only indirectly effective in monetary terms that are coming into focus.
From a purely commercial point of view, it may therefore not be worthwhile to convert existing warehouses. However, if the entire supply chain is taken into account and truck capacity utilization is optimized in this way, the balance may be more positive, as such measures would have a direct impact on freight space shortages and CO² emissions, and cost benefits may even be achieved. However, it must also be taken into account that this strategy not only has an impact on logistics itself, but would have to be implemented long before this, starting with the primary packaging of the goods right up to the point of sale - and not just for individual companies, but for the entire consumer goods and retail industry. However, this requires a view of the entire supply chain, because optimal implementation is only possible if all requirements and technical restrictions and possibilities are taken into account.
Double-decker trucks or automatic loading and unloading are two approaches that are absolutely feasible from a technical point of view, but which fail time and again because it is not possible to get the loading and unloading sides of the transport to cooperate.
At second glance, it becomes apparent that the actually trivial issue of the optimal height of a pallet does present some challenges that require more intensive consideration or coordination between suppliers and retailers.