Stacking Identical Product in Containers / Trailers on Pallets or Slipsheets?

If so you certainly need SLIPSHEET MANAGER - 

Do you transport products in shipping containers or trailers using 'blocks' of identical product stacked on pallets, slipsheets or as free-standing stacks? If so this new, unique and innovative software product can help you pack more efficiently and cut your storage and transportation costs.

The software focuses of maximising the amount of identical product which can be packed into a container or trailer in stacks - if you have mixed products in a container, or you load products by hand without block stacking then you need CARGOMANAGER - see the back page of this guide for details.

SLIPSHEET MANAGER was developed so that companies could load cargo more efficiently using slipsheets (a pallet alternative), but the techniques used have proved equally effective when tackling problems where pallets (or stacks of product) are to be loaded into trailers / containers. It allows you to:

1.1 Introduction.

Standard pallet sizes are often used as a basis for loading containers or trailers, but this can prove inefficient in a number of ways:

For these reasons, and others, the use of slip-sheets (a sheet based pallet replacement) or alternatively the use of custom sizes of pallet is being increasingly seen as both a practical and cost effective route forwards. 

1.2 Basis of Operation.

Given any given product / case size there are a number of software products available to determine volume efficient and practical stacking plans for loading a given fixed load area (e.g. a 1200*1000 pallet / slip-sheet). These include our own PALLETMANAGER software (www.packyourpallet.com). However, as outlined above, neither a standard UK or US pallet (1200*1000 / 48*40) nor a Europallet (1200*800) provides volume efficient loads within any of the standard sizes of shipping container. 

 

SLIPSHEET MANAGER allows you to achieve three key tasks:

1.3 Data Input.

SLIPSHEET MANAGER requires the user to provide information on (a) the case / product size to be loaded and (b) the container size to be used. In addition it allows users to restrict solutions to those which meet their specific constraints. A typical completed input screen is shown below.

The Container DB button (centre left of screen) can be used to select the required container from the database (which can be edited by the user), or dimensions can be directly entered. In the above a case of size 306*100*200 is to be loaded into a 40' standard container.

The analysis with automatically be carried out on standard sizes (e.g. 1200*1000 and 1200*800 for the metric version of the software). In addition stacks of product between the stated length / width (adjustable) limits will be considered. A further Custom Stack Size of 1100*1100 will also be examined - this is explained later. 

Towards the bottom of the Input Screen the user can select either Slipsheet/Block Stack load or a Pallet based load. If Slipsheet is selected a small amount of additional space (here 50mm) will always be left along one side of the container to allow for the projection of the loaded slipsheet. If Pallet is selected then the loading height available in the container (here 2393mm) will be reduced by an amount to account for the pallet base height (here 162mm - Std CHEP). All the above allowances can be changed by the user.

Here we have selected a slipsheet load, but the results discussion below is equally appropriate for a pallet load, though the reduction in height when using a pallet would result in fewer cases / stack. Once the screen is complete the user selects Pack.

1.4 The Results.

SLIPSHEET MANAGER uses the data provided on the input screen to carry out the following calculations:

Firstly the given product is loaded onto standard slipsheet / pallet sizes (e.g. Metric: 1200*1000 / 1200*800 or Imperial: 48"*40" / 42"*42") in an optimal way. Then these stacks are loaded in the best way into the container / trailer and the total amount of cargo loaded recorded. The Custom Stack Size (1100*1100) is also examined in a similar way.

Second the software determines what other custom stack sizes might be used for the given product. These sizes are derived from the case size input on the above screen. For a given case there may be several hundred potential sizes but SLIPSHEET MANAGER will reduce this down by taking account of the size constraints input above.

Each custom stack size will have associated with it one or more patterns which might be used to create the load stack. An example of a possible pattern is shown below. In some instances there may only be a single pattern which might be used, but in other instances there may be several dozen possible optimal patterns. In many cases it will be possible to produce a highly stable stack by rotating alternate layers as shown in the example below. SLIPSHEET MANAGER provides you with powerful graphics facilities to achieve this.

1112*912 (Entry 4 in table overleaf)

In the next stage of the analysis SLIPSHEET MANAGER examines the efficiency with which each of the calculated stacks can be loaded into the stated container size. As will be seen from the results table overleaf the efficiency varies greatly with the best solution to the stated problem fitting 9504 cases / container whilst the worst solution (a 1400*912 stack) loads just 7040 cases / container. The first screen of results (top 11 of 79 solutions) for this analysis is shown overleaf.

The top part of the above screen (on a grey background) simply provides the user with a summary of the data which they provided on the opening screen.

Below this a scrollable window lists all those solutions which SLIPSHEET MANAGER has evaluated. Each line represents a different stack size and associated with each is information about the performance achieved. The top 2 lines always report the performance of the most popular sizes (here the 2 standard European sizes) when used to load the given case size. When first displayed the topmost of these is highlighted (as shown). Line 3 contains the solution for the Custom Size which the user can edit on the Data Input Screen. 

The lines which follow these 3 sizes report (in ranked order) the performance of other custom sizes. We will firstly explain the results for the standard sizes:

(a) 1200*1000 / 1200*800 Results.

The first 2 lines of the results always present the results for standard slipsheet / pallet sizes when loaded with product of the size input. In the above screen 36 cases each 306*100 fit on each layer of a 1200*1000 stack and a total of 8712 cases fit into the container. In practice the case size wastes space when stacked as a 1200*1000 'block', and as discussed earlier the 1200*1000 dimensions do not fit very well into the container. In fact there is over 20% wasted space - AIR!! - in this container.

Lines 2 and 3 of the results repeat the analysis for the 1200*800 and (custom) 1100*1100 slipsheet / pallet sizes. These prove even worse, and allow far less cargo to be loaded into each container.

With the 1200 *1000 line still highlighted the user can select the StackView button to view the possible ways in which the cases could be optimally loaded onto the load area. There are a number of different solutions offered (each of which fits 36/layer), one of which is shown overleaf, but given the (difficult) 306 length dimension of the case there will always be wasted space on the 1200*1000 base.

The Contview button can be used to display two and three dimensional views of how the given stacks can be loaded into the given container. The 3D load picture for the 1200*1000 stacks is also shown below.

Stackview

1200*1000 base, 306*100 case.

This arrangement is one of four possible patterns which provide this optimal solution. The software allows users to display and manipulate the stack arrangement to produce stable stacking plans.

Contview

1200*1000 stacks in given container.

The software initially displays the load plan in 2D and gives numerical values for the free lengthwise and widthwise space. The user can then select 3D display to produce this picture.

For palletised loads the container loading height specified on the input screen will be automatically reduced to allow for the height of the pallet itself. The pallet would be drawn on diagrams when appropriate. When comparing a pallet and a slipsheet of the same size, slipsheets will typically perform better as they allow an extra layer or two of product to be loaded on each stack. However as we illustrate below, the use of non-standard stack sizes will almost always allow more cargo to be packed into the container - often a 10%-15% improvement.

(b) Other Slip Sheet / Custom Pallet Sizes.

Following the results for the standard sizes, the main set of tabulated results tabulate the load performance achieved when custom stack sizes are used. Each line represents a different stack size and the performance achieved when using this in the given container size. The results are ranked in order of efficiency. The screen shows just the first 11 of the 79 possible stack sizes. Information output includes:

The results of using the two standard sizes can be bettered using any of the top 33 calculated sizes listed in the remainder of the table, with the best of these achieving 9504 cases / container - a further 9% improvement.

You will also note that each line is numbered and following this number there is quite often a T code. Whilst all the results calculated can be successfully packed into the given container size, some solutions (those with a T coding- 'Tight Fit') have a limited amount of additional free space. SLIPSHEET MANAGER examines the free space in the load and if this is less than 2% of width or length then a T coding is given. Those without any T coding are therefore a relatively easy cargo to load. Selecting Contview for any highlighted entry will immediately display both the load plan and details of the exact amount of free space within the container.

As might be expected those sizes which provide the highest load quantities are more likely to be a tight fit, though there are examples in the above table (e.g. entry 10, a 1224*1000 stack) which are relatively easy to load (no T coding), are just marginally bigger than standard (by just 24mm) and yet fit over 700 more cases / container than that achieved using a 1200*1000 stack (> 8%).

Types of Pattern:

Each stack size which is presented has an associated pattern code (e.g. NC, C1 etc). In many environments the exact load plan forming the stack will be of limited interest. As will be illustrated later the software includes powerful graphics facilities which can be used to display available stacking plans. In other situations some form of clamp truck may be used to transport the load. The suitability of a solution for clamping is shown by codes C1, C2, C3 and C4.

1.5 The Optimum Solution.

The results table presented above is listed according to the efficiency with which the container is utilised. This would still be so if the container weight limit had come into play, but in such situations the number of layers fitted would be adjusted to meet the container load limit.

Users can naturally print out any or all of the table of results and, as illustrated above, it may well be that there are a number of potential sizes which could be used to provide significant improvements in load efficiency. In addition the user can also appreciate how well standard slip-sheet sizes perform compared with any existing palletised solutions, and compare the performance of standard slipsheet or pallet sizes with any of the custom sizes proposed. 

SLIPSHEET MANAGER does in addition display graphics of both the way(s) in which the slipsheet stack might be constructed, and the way in which stacks can then could be loaded into the container.

The mouse (or up/down arrow keys) can be used to highlight any of the entries in the results table, and following this StackView or ContView selected to display in both two and 3 dimensions the Stack Plan or Container Load Plan.

From a numerical viewpoint the best solution uses a 1118*1000 stack, fitting 36 / stack layer and with 24 such stacks fitting into the container. This gives 9504 cases / container, and given that a 'T' follows the rank number (column 1) we know that it is a somewhat tight fit in the container.

Stackview allows us to view the 2D patterns which might be used to create such a stack (3 in total) and to select one of these (and space out cases) to form a 3D stack as shown below:

The ContView button allows you to view the container load plan in both 2D and 3D. The result for this problem is shown below:

As can (just) be seen on the 2D diagram there is a very limited amount of space available within the container (slight shading on the perimeter) - as detailed in the text just 35mm on the container length and 64mm is unused - hence the 'T' coding in column 1 of the results.

It should be noted that for slipsheet based loads the unused space on the width of the container DOES take account of the 50mm slipsheet lip allowance input for this problem. Thus a total widthwise space of 114mm applies for this solution, with 50mm of this being allowance for the slipsheet lip. 

 

As discussed earlier, should you feel that this container load is too tight then you can quickly display the results for any other of the stack sizes. For example result 2  does not have a T coding, and whilst losing out a little in total load, has free space of 257mm and 64mm on length and width in the container.

Printing Results:

A standard print button allows you to print out part or all of the set of tabular results. 

The 2/3D display of both slipsheet stacks and container load also have a print function which allows you produce detailed 2D/3D reports displayed on both screen and printer, and available in English, French, German and Spanish

In addition any of the 2D / 3D graphics displayed can be cut and pasted via the Windows Clipboard to other windows applications: "Position the mouse at one corner of the required region, depress the left mouse button and move the mouse to 'rubber-band' the area required. Then release the mouse and you will be informed that the region has been copied to the clipboard".

Saving results and Sending to Others:

SLIPSHEET MANAGER also include a Webbase / JPG file creation / display function.

This allows any reports to be saved to disk in .JPG format. Such files can then:

For those requiring solutions to problems of loading mixed product within a container our CARGOMANAGER software is likely to be of interest ( www.packyourcontainer.com ). 

If you wish to tackle pallet loading problems (covering all aspects from product design through to case design and optimal pallet loading) then PALLETMANAGER is likely to be of interest ( www.packyourpallet.com ).

For further information on SLIPSHEET MANAGER, PALLETMANAGER and CARGOMANAGER please see our websites or contact us using the details provided below.

Gower Optimal Algorithms Ltd, 5 Whitestone Lane, Newton, Swansea, SA3 4UH, UK.

sales@goweralg.co.uk / Tel: +44 (0)1792-368413 / Fax: +44 (0)20 7748 6130

www.goweralg.co.uk / www.packyourpallet.com / www.packyourcontainer.com