(Covers: Introduction to options, Top layer option, Mixed stacking modes.)

When developing the three dimensional pallet stacking arrangements in Palletise and Collation, we have so far made 2 assumptions:

a. That each pallet layer should consist of the same number of cases, placed such that the same dimension is vertical on all layers.

b. The arrangement used on each layer of the pallet is essentially the same, save for the possibility that alternate layers could be a rotation or reflection of the base layer.

This section examines how each of these assumptions may be relaxed, so as to potentially obtain improvements in both the number of cases packed per pallet, and the stability of the stacking arrangements.

11.2 The Top-Layer Option.

In Palletise and Collation modes (and as we shall see in Section 12 in Tertiary mode), the number of layers fitted (each layer being of identical height) will be restricted by the limits placed by you on pallet loading height and/or pallet loading weight.

An examination of the Results Summary Screen (Screen 5) may show that a small increase in one or both of these limits can allow an extra layer to be fitted, and the AddLayer feature may be used to examine the effect of such a relaxation.

However, there may well be situations in which, for example, the height constraint may not be relaxed, for example when pallet racking height provides a constraint. In such situations it may be acceptable to consider placing a single layer of cases on their side to form a top layer on the pallet stack, without changing the height and weight constraints applied.

PALLETMANAGER allows you to investigate the effect of utilising a single top layer of cases placed on their side. This is achieved by selecting the appropriate 'tick box' on the Advanced Options screen (Screen 4), selected from the Screen 3 where Pallet and Style details are set.

The operation of the Toplay feature can best be illustrated by an example.

In the Guided Tour (Section 3) a Collation example was studied in which 12 primaries each 65 * 55 *52 were collated for form a case. The results screen obtained in that Section is shown below:

Whilst it was shown that some improvements could be obtained if the height and/or weight constraints were relaxed an alternative route to an improved solution is possible.

Assuming the height and weights constraints were fixed, then if it were acceptable for the pallet stack to have a single top layer in another orientation, then this might provide a further improvement.

In order to allow this to be investigated the Advanced Options screen (Screen 4) should be selected from Screen 3 where Pallet and Style details are selected. A tick box on this screen allows top layer rotation to be examined.

If the same problem as discussed in Section 3 is examined in this way then the following results screen will be displayed:

If we compare the above 2 screens we can see that the previous 'best' solution is now in 3rd place and there are two arrangements using a single top layer in an alternate orientation which give lower cost solutions - without the need to break / relax height or weight constraints.

It should be stressed that the case dimensions of the base layers and of the top layer are the same, and the top layer simply represents identical cases placed on their side.

In the usual way a particular case reference may now be selected, and the pallet patterns displayed.

If however a solution is selected which utilises a Top Layer in a different orientation from the rest of the stack (In this instance we will select case reference 1), then we will need to choose not only the arrangement to be used to form the base layers of the pallet stack, but also the arrangement which should be used for the top layer. This will help us to ensure that the top layer is suitably supported by the layers below.

After selecting a stacking arrangement for the base layers in the usual manner, you will find that you are unable to select Print. 

Instead you will need to select Pick toplayer to pick your chosen top layer.

At the bottom of the screen the base arrangement layer lying directly below the top pallet layer is displayed. 

At the top of the screen, displayed in a 'window' is the first possible arrangement which may be used for the top layer. The possible top layer arrangement(s) may be examined or manipulated using the usual options buttons.

Having on-screen both the top layer arrangement, and that of the layer immediately below, enables you to choose a top layer arrangement which is appropriately supported. Once the desired top layer is displayed the selection of Print will allow you to select the reports which are to be printed.

11.3 The Mixed Stacking Mode.

When using Palletise, Collation and Tertiarymodes, whether or not Top Layer mode is in use, the stability of the pallet load will depend on the degree of support and interlock between layers on the pallet.

PALLETMANAGER has been significantly enhanced in recent releases to include a far greater range of optimal pattern types, and to allow for the re-arrangement of patterns (using move and space options) so as to form a stable stack.

However, there will still occasionally be situations when the reflection / rotation of the pallet pattern does not fully satisfy the user in respect of stability and interlock between layers.

You may select a mixed mode of pallet stack generation in which alternate pallet layers are not simply transformations of the basic arrangement.

This mode may be selected by selecting for Alter Mode, one of the buttons on Screen 6 - Layout Selection.

When this mode is selected a screen such as that shown below is displayed. The lower part of the screen shows the first possible arrangement for the first layer of the stack (and layers 3, 5, 7 etc). Above this is the arrangement for the second layer of the stack (and for layers 4, 6 etc). 

When you first select Alter Mode both arrangements will be identical, and the bottom pattern will be displayed in a 'window' - a containing rectangle.

This window is used to indicate to which arrangement the commands issued by the user will be applied. The Swap option may be invoked to change the window (i.e. to allow you to modify the other arrangement).

The usual movement and spacing options are available for adjustment of both arrangements, but the 2 and 3 dimensional screen views of the pallet stack can only be selected when the window is set for the base arrangement.

The Identical, Mirror, Flip and Rotation options are always applied to the arrangement in the top half of the screen only. Thus, if the bottom layer is 'windowed' and one of these commands is issued, then a stack is formed from the pattern shown at the bottom of the screen, and the appropriate rotation / reflection (as selected) of the pattern shown at the top of the screen.

Selection of Print then will initiate a print of the chosen arrangement, or, if the arrangement makes use of the Toplay feature you will first need to Pick toplayer before selecting Print.

At any stage Alter Mode may be selected to return you to the 'normal' single arrangement mode.

Therefore Mixed Stacking Mode enables you to combine together different pallet layouts. Those available for selection will always be for the same case size, with the same vertical orientation, and the same number per layer.