(Covers: Introduction, Input screens, Results screens, Improving results, Layout selection and printing, Nesting of primary units, Case strength module, Primary Image Display, Graphics Image Requirements)

6.1 Introduction.

The discussion in Section 5 on techniques for improving solutions covered techniques which were typically valid when using any of the modes Palletise, Collation or Tertiary. This Section provides some additional information relating to Collation mode and describes in great detail the Case Strength module.

6.2  Input Screens.

After selecting Collation mode, Screen 2 allows entry of primary unit details. This takes an identical format to input in other operating modes. Of note here are:

Primary Dimensions are normally held to 1 decimal place (e.g. 88.2), but on systems where STORE is not enabled 2 decimal places can be used.

Primaries/Case is the number of primary units that are to be contained in the 'case'. The range is now 1 to 2000. 

The ability to specify a collation of 1 unit has been provided to cater for users who wish to determine the external dimensions of a case (together with the palletisation layouts appropriate) from its internal dimensions.

Annual Case Volume is the number of cases, each containing the number of primary units specified above, which are produced annually.*

* At a later stage, once all product details have been entered, users may specify alternate collation quantities as described below. If this is done then the entries for Units / Case and Annual Case Volume are used to calculate the annual production of primary units. This is translated into appropriate case volumes for each collation quantity. Thus one is able to compare packaging and distribution costs for different collation quantities on a common basis.

This version of PALLETMANAGER caters for up to 300 cases on each pallet layer, and up to 2000 different potential case sizes in a single run.

On selecting Continue Screen 3 - Pallet and Style selection is displayed:

The details or the pallet loading area can be editing on this screen (for this run only) or the Pallet Database and/or Style Database can be accessed to select suitable values for Pallet and Style. 

Details of both databases is given in Section 4.

Normally from this screen the Pack option would be selected, however the Advanced Options button (discussed also in Section 5) provides access to the following additional facilities:

Selection of Cylindrical Packing Option:

Unless the advanced options screen is selected the dimensions entered for the primary will always be assumed to relate to a cubic item. A tick box on the Advanced Options screen (Screen 4) - or above on Screen 3 - allows you to indicate that a cylindrical item is being packed. Full details on all aspects of cylindrical packing are given in Section 10. 

Selection of alternate collation quantities:

Also available on the Advanced Options screen is the ability to specify alternate collation quantities to be used in addition to that specified on the Primary Input screen.

You can enter up to 3 distinct alternate collation quantities, or, alternatively, a range of quantities between a lower and a higher value. If you wish to enter a range (e.g. 4 to 12) then enter the lower limit as Alternative 1 and enter -12 as Collation Alternative 2. (Notice the negative sign). Values up to 2000 may be specified as individual values but for a range the upper limit is 999 (i.e. -999). 

These values are considered at the same time as the 'expected collation quantity', and the results for all collation quantities are tabulated together. In doing so the figures entered on Screen 2 for Primaries / Case and Case Volume are used to determine the 'Annual Production of Primary units', and cost calculations for all collation quantities are based upon this common basis. 

It is also possible to specify a 'step' value. Say in the above example there were practical reasons why the collation quantity must be multiples of 2. Using the above procedure would produce solutions (for 5, 7, 9 and 11) that were not acceptable. The Step value can be used to avoid this happening, and the entry in Alternate 3 (if different from the standard collation quantity) is used for this. To examine all collation quantities between 4 and 12 in steps of 2 you would make the following entries:

Alternative 1 (from) : 4

Alternative 2 (to limit) : -12

Alternative 3 (in steps of) : 2

The original collation value specified, together with values of 4, 8, 10 and 12 will be examined.

Sensitivity analysis on size using the Fixed Volume module.

If the primary dimensions entered earlier might, if advantageous, be varied in any way then the Fixed Volume module - Selected from the Advanced Options Menu - can provide an effective mechanism for performing such an analysis - full details are given in Section 7 of this manual.

6.3 Results Screens.

When Continue is selected from either Screen 3 - Pallet & Style Selection, or Screen 4 - Advanced Options, case sizes are generated, those which exceed user limits discarded and the palletisation efficiency of those which meet user constraints are calculated. Then these results are ranked according to cost. Cost information provided by the user on the Pallet and Style database screens are used to calculate transport and packaging costs for the annual case volume defined earlier on Screen 2. (If cost values have been set equal to zero then the report in ranked according to the number of primary units fitted per pallet.) A ranked list of results is then presented and you can browse through these before using the left mouse button to highlight the design you wish to investigate further.

In Collation mode up to 2000 different case sizes (all of which will have met your stated constraints), can be considered. The best 99 of these are reported.

The default ordering of both screen and printer reports is determined by the Annual Total Cost of that solution (where cost data has been specified), or by primaries per pallet otherwise. The External Case Dimensions quoted are based upon the primary unit details, the collation, material thicknesses and gaps and headspace.

This very powerful ranking feature can result in the least cost solution not actually fitting the most units / pallet. The latest version now provided an additional set of buttons on the tabular results screen (Screen 5), so that the display can be 'toggled' between the traditional cost based listing and one sorted according the the quantity of product / pallet.

Whichever ordering system is requested, then on the right hand side of the printout are given area and volume utilisation figures for each case, together with the amount by which height and/or weight constraints must be relaxed for an additional layer to be fitted.

When alternate collation quantities have been specified both screen and printout gives details of the collation quantity associated with each line of results, together with the total number of primary units per pallet.

We have recently added a further feature to Collation / Tertiary mode. In earlier releases users needed to highlight a table entry and then select Collation in order to view how a case was constructed. Now, as soon as an entry is highlighted a Mini-Collation picture is automatically displayed. This changes as each entry is highlighted.

There are situations where incorrect configuration of the software on networked machines might result is multiple such pictures being displayed as users browse through results. Whilst users can close any such window using the Closure control on the top right of the window, ideally your network configuration should be changed. This is discussed in Appendix 1.20.

6.4 Improving Results.

Both the Guided Tour and Section 5 of this manual provided a range of options available for results improvement. These included:

• The use of a small amount of overhang on the stated load area:

Allowing some overhang can be investigated by using the Back button and changing the appropriate entries on the Pallet Details screen (Screen 3). PALLETMANAGER will calculate solutions both with and without the overhang you specify. The ranked solutions report will show a < symbol (less than) on the right hand side against solutions which do not use overhang. This makes it easy to see what improvement overhang might give.

• The use of the Fixed Volume module.

The results presented are in all cases the best that can be achieved using the given case size packed onto the given pallet. However it may be that you have some slight flexibility in defining the loading height or weight, or you may be prepared to use a small amount of pallet overhang, or consider an alternate packaging specification. In addition it may be possible to use alternate collation quantities or reduce packaging allowances, or to vary slightly the primary dimensions using the Fixed Volume feature described in Section 7.

• The use of the Do Better function.

This is selected from the Summary Results Screen - Screen 5. This is described in detail in Section 16 of the manual.

6.5 Layout selection and printing.

Having highlighted an entry for further examination selecting Layout brings you to the Layout Selection screen (Screen 6). Here the various optimal layouts for the highlighted solutions are presented and manipulated. This is identical to the process in Palletise mode and is described in detail in Section 5.

Having selected a pallet layout the following screen (Screen 7 - Notes, Screen and Printer Reports) allows you to enter additional notes to appear on the reports and to view / print these reports. In many instances the level of detail provided on the reports without the addition of notes will be sufficient. In Collation mode it is also possible to add information about the Case Style used automatically by selecting the ColNotes button. This 'toggles' between display /non-display of these automatically added notes.

6.6 Nesting of Primary Units.

In some instances the primary units may be such that they will nest into one another. Thus, for example, the height of a single primary might be 85mm, but if the product could be nested to a depth of 65mm, a stack of (say) 3 units would only require a total of 125mm.

It is possible to examine such situations by utilising the 'headspace' variable, which would normally only be specified if a gap was required in a case above the packed product.

In the example quoted here a product height of 20mm could be specified together with a headspace value of 65mm. The product height would be entered on Screen 2 and the headspace on the Packaging Style specification screen.

Thus a single 'layer' of product would require:

65mm + 20mm = 85mm

and each additional layer would add 20mm to the height required.

6.7 Case Strength Module.

The remainder of this section of the manual considers the Board Selection module available in Palletise, Collation and Tertiary modes of operation. This module provides some guidance of the influence of case design on stacking strength.

It should be emphasised from the outset that the types of PALLETMANAGER output produced by BoardSel can only be used in conjunction with your own experience and judgment to specify appropriate materials and safety factors. They should always be treated as a guide which should be verified by Case Designers etc.

On the Tabular Results Screen (Screen 5), selection of the Advanced Options button allows you to select the BoardSel Option.

The information displayed and printed in the BoardSel module is partly derived from the information you enter on the main input / pallet and style screens, and partly from a user modifiable database of potential case materials and their characteristics. When first installed this database contains a set of information derived from a series of case studies conducted by one PALLETMANAGER user, but the database information will in all likelihood require to be customised be you so as to meet your individual requirements.

The output from the analysis comprises of the following information:

• The case size, number of cases per pallet, and total pallet weight.

• The average load on each case at the bottom of a one-high pallet stack.

• The case thickness specified by you on the Case Styles screen earlier in the analysis (in Collation / Tertiary modes). This value has been used in the calculation of the external case dimensions.

• Information of the various safety factors which have been applied. These are discussed later.

• For various grades of board (the names and characteristics of which are held in a database which is described later), the following is presented:

•  Description of the board type (from the database).

• Caliper (thickness), obtained from the database.

• The estimated compression strength of a case of the above dimensions in Kg. The basis of this calculation is described later.

• The number of pallets high which calculations suggest this board thickness could support given the information supplied. Once again the basis of the calculation is described below.

It must be stressed that the above calculations, although based upon procedures which have been found to be successful in practice, will be influenced by a variety of different factors. They are also based on initial database entries which may well need to be modified in the light of your specific application.

A typical results screen (Screen 5b) is shown below:

The estimated case strength using each board grade is given. This is influenced by various factors including the case dimensions and details of how this is calculated is given below. For each grade of board the suggested number of pallet high is also given. Once again the basis of this calculation is outlined below. In this instance most grades will only support a one high stack, though some of the thicker / heavier grades might permit a two high stack to be used.

Other grades of board (together with their associated strength and 'pallets high' information) can be displayed using the More option.

It is not necessary to restrict examination to the case reference number first selected. The Previous and Next Reference buttons options can be used to view information on other case reference numbers. You will notice that other reference numbers may exhibit very different characteristics. The load on each bottom case will vary significantly as the number of cases per layer changes between different designs. This is also true of the Estimated Case Strength which depends on the case length and width values.

BoardSel - The Theoretical Basis

As users of PALLETMANAGER will be aware there are a wide range of approaches that may be used to determine case strength. The literature on the subject is very extensive and no single approach can be said to dominate.

It is generally accepted that the compression strength of a case is a good measure of the overall strength, robustness and rough handling resistance of the case. The following factors are of particular importance:

• The edge crush resistance of the corrugated board.

• The thickness of the corrugated board.

• The case perimeter.

In addition to these, defects caused by faults in conversion may impair the case compression strength considerably. The first requirement, in specifying a case construction, is to determine the "Compression Failure Load" (CFL) of the case. Once a value for the case CFL has been established a construction can be chosen that will meet the requirements.

Thus we are faced with determining:

A. The Potential Load on a Case.

The Compression Failure Load (CFL) is the likely maximum load which any case in a given pallet stack is likely to encounter.

a) Single Height Pallet Loading

In some situations a single pallet may be stacked to a given height limit without any additional pallets being placed on top. In such circumstances the load likely to be experienced by the bottom-most case in the stack can easily be derived from the formula:

Load = ( Stack Height - 1 ) * Pack Weight

Pack Height

To calculate the required C.F.L. it is usual to apply correction factors of:

Climatic Correction: * 2.0

Time-in-Stack: * 2.0

b) Multiple Height Pallet Loading.

When considering loads experienced by packs during palletised distribution (where several pallets may be stacked on top of one another), it is necessary to consider the effect of the pallet itself on load distribution.

For pallet loads stacked more than one high the point of maximum stress on the cases is transferred from the bottom cases of the whole stack to the top cases on the bottom pallet load. Thus in a multi-pallet stack we need to calculate the load on the TOP layer of the bottom pallet and apply to this appropriate correction factors. Thus, for a two high pallet stack the calculations would be:

(Pallet Weight / No of packs/layer ) * Pallet base board factor

The pallet base board correction factor accounts for the fact that most pallets are NOT close boarded. A value of 2.4 is typically suggested, though this default value may, as described later, be modified by the user. In addition, once again climatic and time-in-stack factors need to be applied. Values close to 2.0 are typically used for both of these, and initial default values of 2.0 are applied by PALLETMANAGER.

An example of the calculations carried out in such a situation is given below:

Example:

Pack Weight: 21.36 kg; Pack Dimensions: 400 x 300 x 315 mm

Pallet Load Weight: 666 kg; No. Packs/Layer: 10 - Uses a 2 High Pallet Stack

Load on a pack = Pallet Weight /(No per layer)

This result is then multiplied by the pallet base board correction factor.

= (666 / 10) * 2.4 = 160Kg.

Additional safety factors (of 2.0) for climatic conditions and for the time in the stack are then used to multiply the above figure to give the required Compression Failure Load. In this instance a Compression Failure Load in this instance would therefore be of the order of 640kg.

The calculations used for stacks of 3 or more pallets are similar to the above.

Thus, for a given pallet load the maximum stresses experienced if stacked 2, 3 or more pallets high will be calculated by PALLETMANAGER. This is then compared with the strength offered by various board grades, and the result - the maximum number of pallet loads which should be considered - reported on screen and printer.

The calculation of the strength of a given case is the subject of the next section of the manual. Examples of alternative values for both fatigue and climatic factors are given overleaf:

In PALLETMANAGER initial defaults of 2.0 are used for both these factors but as described later these may be modified by the user.

B. The Likely Strength of a Case Design.

Once again a wide range of alternative formulae have been proposed to predict case performance but given the variability of materials and suppliers this must necessarily be treated with some care.

A formula which is applied by a number of PALLETMANAGER users is based on the Edge Crush, Board Caliper and external dimensions of the case. PALLETMANAGER has information on external dimensions, and utilises a user database to hold details of Board Type, Edge Crush and Board Caliper. The detail of the database, and how it may be modified, is given later.

The suggested formula is:

(1.515 * EC) ^0.57 * CAL ^0.87 * (L + B) ^0.47 * 0.9

= Theoretical Case Compression Strength.

Where EC = Edge Crush (kg/cm)

CAL = Board Caliper (mm)

L = External Case Length (mm)

W = External Case Breadth (mm)

This formula includes a 10% reduction factor to account for conversion damage.

This calculation is automatically carried out in PALLETMANAGER when the BoardSel option is selected. We therefore have available:

The predicted loads which the most loaded case in a stack will experience, either in a single stack or when loaded two or more pallets high.

The predicted performance of a case made of fibreboard of a particular type. Thus PALLETMANAGER is able to present:

- The estimated compression strength of a case of the calculated dimensions in Kg.

- The number of pallets high which calculations suggest this board thickness could support given the information supplied.

The Compression Analysis screen allows you to browse through the various board grades held in the database using the scroll bar.

Also, although before entering the BoardSel option you Selected one of the available case reference numbers, you are able to browse through all those displayed on the previous Results Summary screen (Screen 5a) examining the implications of case design on compression strength. 

You may also move on to Calculate layouts for the currently displayed Case Reference Number. Selecting Back returns you to the Results Summary Screen.

You should note that the screen / report also indicates above the tabulated information the Case Thickness specified by you as part of the Case Style information. This thickness is the one which is used to determine the external dimensions of a case. 

It is important that the Caliper value for the Board Type you eventually choose matches that of the Style record. If it does not, then the actual case (of stated internal dimensions) will, of course, have external dimensions greater than or less than those calculated within PALLETMANAGER.

For each grade of board in the database an estimate of the number of pallets which can form is stack is given. This is done by reference to the various calculations described above and it must be stressed that the basis of this depends heavily on the edge crush strength (from the database), and on the compression strength formulae and 'safety' factors detailed earlier. In addition, it is important to take account of the handling to which the pallets are to be subject, and the type of pallet pattern which you will subsequently select. Our software can only provide a guide as to what is likely to be successful in practice.

The theoretical strength calculations for a case assume that it is placed in its 'normal' (stronger) vertical orientation. If palletisation solutions are chosen in which case orientation of the top layer differs, then the above analysis clearly is INVALID.

The "Compression" Database.

When PALLETMANAGER is installed a sample database file is provided. This contains:

Values for the five safety factors described above, they are (in order):

• The Climatic and Time-in-Stack factors applied for single high pallet loading. Initial values of 2.0 are used for these.

• The pallet base board correction factor. An initial value of 2.4 is used for this.

• The Climatic and Time-in-Stack factors applied for multiple high pallet loading. Initial values of 2.0 are used for these.

These five values are found, in the order given, on the first line of the file COMPRESS.DAT. This file will be found in the PALLETMANAGER directory and is accessed every time the BoardSel option is selected.

The five values must all have a decimal point and be spaced apart on the same line. The following lines (up to 50 entries, beginning on line 2), contain details of board types. Specifically:

• Board Grade Description,

• Edge Crush (Kg/cm),

• Caliper (wall thickness - mm).

The database can be viewed and edited using a simple editor (EDIT for example), as long as the exact layout / length of entry is maintained. Thus, given knowledge of the Edge Crush and Caliper of other board types these can be added to the database. Unused board types can be easily deleted.

6.8 Primary Image Display.

[The text below (6.8 and 6.9) has been updated slightly from some of the printed material in the light of late implementation changes.]

PALLETMANAGER reports as standard do not include any detailed graphics images of the products being packaged - the primary units - these being represented and displayed in simple cubic or cylindrical forms. In most instances such a presentation is quite sufficient.

However we have now introduced a new feature in COLLATION mode - the ability to merge graphics images of cubic primary units onto the palletise and collation screen / printer and Webbase reports. This feature is described below:

Immediately prior to the display and printing of reports Screen 7 is displayed (or in STORE mode Screen 9). Both screens allow you to select which reports you wish to view on screen / print / email etc. A new option on this screen - Primary Images - only displayed in Collation mode - allows you to bring up a screen from which you can select graphics files which will superimposed on the surfaces of the primary as displayed on Palletise and Collation reports.

The images chosen will continue to be displayed / printed as part of reports until either you re-select and change Primary Images or you return to Screen 5 (from where you select the case and primary that you wish to examine in more detail).

On selecting Primary Images the following screen is displayed:

To the left hand side of this screen are 3 large buttons which you can use to select graphics files (.jpg or .bmp) - details below - which will be superimposed on the 3 visible faces of each primary unit when Palletise and Collation reports are produced. Initially the entries for each picture (filename and location as shown) will be blank, but once you have selected a picture for a given face, details of this will be retained when you subsequently enter the selection screen, whether in the same session or subsequently. 

Actioning any of the 3 file selection buttons will activate the standard file Windows selection dialogue you would use with any other application. You can browse your machine to find suitable images. However the starting point for this search is always a folder prodimages which is located directly below the installation folder you use for PALLETMANAGER (default c:\pmnt). It is suggested that this is a logical location in which to store product images to use with PALLETMANAGER. Such images may be produced by a wide range of different packages / tools.

The initial search option is for .JPG files but you can naturally change this (base of the selection box) to search for .BMP files.

Adjacent to each of the 3 large selection buttons are details of the dimensions of the primary face being referenced. This is provided to assist you in distinguishing faces. You can of course view the Collation report to clarify things prior to selecting the graphics images to be superimposed.

You can select images to superimpose on any or all of the 3 faces. Having selected an image you can also request that the image is rotated through 90 degrees before being placed on the face. All images are normally superimposed on the selected face using the 'natural' orientation of the graphic - and will reduced in size or enlarged as necessary (keeping the aspect ratio constant) to cover the surface. It is suggested that you firstly view the Palletise and Collation reports using the default orientation before (if necessary) rotating one or more of the images.

At the bottom of the screen are 3 buttons:

No images required - this returns you to standard view / printing display screen. No images will be used when drawing, but details of graphics files selected (if any) whilst on this screen will be available when you re-enter the screen.

Clear above entries - this blanks out any entries made on this screen and then leaves you to make new entries or select either of the other two entries (i.e. No images required / Use Selected Images). 

Use Selected Images - this takes the details entered - between 0 and 3 files selected - and moves you on to the standard view / printing display screen.

6.9 Graphics Image Requirements.

The above file selection procedure allows you to select either .JPG or .BMP images to be superimposed on the Palletise and Collation reports in Collation mode.

Images may be in 8 bit or 24 bit BMP format or 24 bit JPG format - a 24bit image is preferable. The most suitable size (pixels) for any such images will depend on many factors - the screen and printer resolution, the size of primary as drawn on the report page etc. You should also realise that the image will appear in perspective and thus any detail will necessarily be 'lost in translation'. This is a feature of the resolution possible on screen / printer and not of our software.

As a starting point the image provided should ideally have a height / width of around 200 - 500 pixels. If the image is of a product face then obviously this will / should have a length / width ratio which equals that of the appropriate product dimensions. As discussed earlier it is suggested that such images be stored in the folder prodimages which will be found directly below the folder in which PALLETMANAGER is installed.

Whatever image size is provided, this will be adjusted (up or down - keeping the length / width ratio constant) to fit the area available. Thus if the dimensions of a face of the product are (say) 200mm * 100mm, then the image provided should have a pixel ratio of 2:1 - otherwise part of the face will have white borders. If the images used are taken from the product (e.g. scanned or photographed) then the pixel ratio should naturally match the ratio of the product dimensions.

However, as discussed above, the translation of a rectangular image to be superimposed on a perspective view will inevitably cause some loss of image quality. It is suggested that you / your IT function experiment with various sizes of image. Given the differences that will always exist between on-screen and printer resolution the effect of size changes on both screen and printer operation should be tested. An example of how product images display as part of a palletisation report is shown below:

In this example the front face of the product was 145mm high by 108mm wide. An image file for this face of 510 pixels high by 381 pixels was used (the same ratio). The PALLETMANAGER Collation Report includes a larger view of the collated products and the quite large pixel count of this image produces a very good image reproduction at this larger size. 

Further important technical notes:

1. The image sizes suggested above will on most devices produce a reasonably good image on both printer and on screen. Those using the Webbase function database should also test the output quality of images on the Webbase .JPG files.

2. Whilst images added to reports WILL be saved in the Webbase, they cannot be stored in the STORE database. Reports produced using superimposed images which are then saved to the STORE database will be reproduced in future (reprinted etc) without the superimposed graphics. However the same facility to superimpose images is available from STORE Screen 9.

3. Given the much reduced file sizes associated with .JPG files as compared with .BMP you may well prefer to use the .JPG file format. 

4. Whilst images will display to screen without any noticeable delay there will be a slightly increased print time when printing reports containing images to a printer or a PDF printer system.