1 : Introduction

    In this tutorial, you will learn how to manage the information related to a product’s variants. You will be able to:

• Use the variant mode and assign an operation to a particular variant
• Display the list of variants attached to the product and modify it
• Display and analyze the information related to the workstations concerning the variants

2 : Defining the product 

    The product we will study in this chapter is a CD. Lets suppose that Optimal Design has to sell a new product in both the USA and Europe. As these countries have different habits and legislations, the packaging of the product before its shipping will be slightly different. Let’s suppose that we have so many orders from the both countries that we are obliged to create a packaging line with several people working on workstations. This could lead to the list of operations mentioned below. For those who are interested in a detailed analysis of the operations and the way the precedence graph has been built up, an extended description is available here.

    The table below represents thus the list of operations with their corresponding manual operating time (since all the operations are executed manually).

ID	Name	Times	USA	EU
1	Take and place a White internal box on the table	300
2	Open the White internal box	200
3	Place the CD box on the table	300
4	Open the CD box	200
5	Insert the Folder into the CD box	450
6	Place the CD into the CD Box and close the CD Box	710
7	Place the CD Box into the White Box	300
8	Close the White Box cover	100
9	Place the Program License Agreement onto the Box	350
10	Place the poster onto the Box	350
11	Insert the Registration Form into the Quick Start Manual	510
12	Place the advertising folder onto the  Box	300
13	Place the Workshop Announcement folder onto the Box	300
14	Place the Full Manual onto the Box	300
15	Place the Quick Start Manual onto the Blank Box	300
16	Insert the White Box into the OD for USA Box and close the box	850
17	Take and place a Brown internal box on the table	100
18	Place the CD Pocket onto the Table	300
19	Open the CD Pocket	100
20	Place the CD into the CD Pocket and close the CD Pocket	700
21	Place the CD Pocket onto the Box	100
22	Insert the Brown Box into the OD Box For Europe	100

Product Description Table

    The file corresponding to this example has already been created by us. Its name is: “VariantsProjectStep1.tsv”, you can open it by using the submenu example of the file menu.

    Load the “VariantsProjectStep1.csv” file, you will see the precedence graph shown in the following figure.

Figure 2.1

3 : The variants in the "Operations" environment

    In the operation tab, click on the variant button, on the right of the buttons bar.()

    You will obtain the following figure :

Figure 3.1

Two major changes can directly be observed on this figure: A “variants navigator” displaying the current variant features has completed the buttons bar The precedence graph itself has changed and displays now the status of the current variant

    Let us first examine in more details the “variants navigator”. It contains:

• A field for the display of the current variant name (Default Variant 1 in the figure 3.2)
• A field for the display of the current variant percentage in the total production (100% in the figure 3.2)
• A minus (-) and plus (+) button to scan the variants

Figure 3.2 

    If we now look at the precedence graph we can see (Figure 3.3) that:

• its color has changed, corresponding to the color of the current variant
• there is a small box at the top left of each operation frame. That box can be checked or unchecked depending on the fact that the selected operation is present or not in this variant of the product.

Figure 3.3

    For the moment, our product has only one variant, corresponding to 100% of the production, but we want to have two variants:

• One for the USA, corresponding to 70% of the production
• And one for Europe, corresponding to the remaining 30% of the production 

    To do this, click on the name of the variant in the variant navigator. (See figure 3.2). The “Change Variants” window will pop up, as illustrated in the next figure.

Figure 3.4

    Let us first add a second variant in the list. To do this, click on the "Add One Variant" button. ()

    A second variant has appeared in the list. That variant is called "Default Variant 2". It has an other color than the first one, and is set to 0% of the production.

    We will now adjust the data represented in that list. Click on the first variant, you will see on the bottom of the window that the name of that variant, its percentage and its color are displayed and can be modified. Type “USA” instead of “Default Variant 1” in the “Name” field and “70”, instead of “100” in the “Percent” field. If you want to modify the color of this variant, you can click on the “Color” field representing it and select a new color in the color dialog box. Once you have done those modifications, click on the “Apply” button in order for them to become effective.

    Select now the second variant and type “Europe” instead of “Default Variant 2” in the “Name” field and “30” instead of “0” in the “Percent” field. Once you have chosen the color you like, click on the “Apply” button to make these changes effective. The “Change Variants” window should look like the following one.

 
Figure 3.5

    Now that the list of variants is correct, you can close this window by clicking on the “Close” button.

    You can switch from the variant "USA" to "Europe" by clicking on the plus and misnus button of the naviagator window. If you select the Europe variant, you will see that all the operations are red crossed as shown in the following picture. This is of course unwanted since it would mean that no operation has to be carried out for this variant.

Figure 3.6

4 : Assigning operations to variants

    We will now define the operations that are executed for a particular variant. In order to explain it more easily, you will first change the display mode of the operations, to show their numbers. To do this, select the “Operation/View Preferences/View Numbers” option in the main menu.

    You see now the same precedence graph with a number identifying each operation instead of its name. Operations 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22 have to be uncrossed because they belong to this variant.

    To uncross them, you have two possibilities:

• Click on the small checkbox above each of the previously mentioned operations. This will uncross each operation, one by one
• Keep the “Shift” key pressed and select all the previously mentioned operations. While still keeping the “Shift” key pressed, uncheck one of the small boxes above one of the selected operations. This will uncheck all the selected operations simultaneously

    For the "Europe" variant you should obtain the following precedence graph.

Figure 4.1

    Use the variant navigator buttons, to see the graph corresponding to the USA variant.

    You can view now that there are two small boxes above each operation. The first box on the left represents always the current variant and the second box represents the next variant (as in our case there is only two variants, the second one is the Europe variant).

    You see that for this variant, all the operations are currently selected. Actually, the operations 17, 18, 19, 20, 21, 22 do not belong to this variant. You will thus have to check the left boxes attached to these operations.

    When this will be done, you will get the graph represented in the following figure for the USA variant.

Figure 4.2

    All the data concerning the variants of the product are now correctly defined. In order to avoid to lose those data, you can use the option “File/Save As” from the file menu to save the file.

    Switch back to the name representation of the precedence graph by selecting the “Operation/View Preferences/View Names” option in the main menu.

    In the next section, we will see what influence has the introduction of variants into the “Workstations” environment.

5 : The variants in the "Workstation" environment

    You can download the file corresponding to this step in the "Example" submenu of the File menu by choosing the "VariantsProjectStep2.tsv" file.

    In this section, we will see the impact of the presence of variants in the “Workstation” environment. 

    Enter in the “Workstation” environment by clicking on the “Workstation” tab. There is no workstation defined for the moment. We will create 5 workstations for this product. To do this, press the "Add One Workstation" button ()five successive times, you will then see 5 empty workstations. Go to the line menu and choose the "Edit Cycle Time And Max Peak Time", the following dialog box will appear :

Figure 5.1

Set the cycle time to 1600 and the max peak time to 1800. Click on the "Apply" button on the first top part of the window.

    Click now on the first workstation and select the first operation. Click on the "Assign Button to Workstation" button () in order to add the first operation to the first workstation.

    Select now operation 2, and click on the same button in order to add operation 2 to the first workstation. Repeat this for operations 3, 4, 5 and 17.

    If you are not in the variants mode, click on the "Variant" button () to activate it and select first the “USA” variant. If you look in the “Workstation Details” zone (the left area in the workstation tab), you will see that there are two columns showing the operating time of the workstation (Figure 5.2). The first column (the main one) in blue shows the global average operation time (on all the variants) of the workstation. The second column on the right side of the main one, is colored with the chosen variant color and represents the total operation time needed by the workstation to carry out all the operations of this particular variant. In this example, it is higher than the average. You can also see that the operations required by this variant are the following: 1, 2, 3, 4 and 5. If you select now the “Europe” variant (5.3), you will see that only operation 17 is required by the variant and that the total operation time of this variant is lower than the average.

Figure 5.2

Figure 5.3

    You can apply the same method for workstation 3 and add operations 10, 11, 12 and 13 to it. For workstation 4, you have to add operations 14, 15 and 16. And finally, for workstation 5, add operations 18, 19, 20, 21 and 22.

    You can, of course look at the details of each of these workstations and see their duration variant by variant.

    The same simplified display of the workstation operation time is also available on the global display of the line as illustrated in Figure 5.4 for the “USA” variant, and in Figure 5.5 for the “Europe” variant.

 Another interesting information you can obtain from the display of Figure 5.4 and Figure 5.5 is:

• The maximum operation time required by the slowest variant for each workstation, represented by the red horizontal line;
• The minimum operation time required by the fastest variant for each workstation, represented by the green horizontal line.

Figure 5.4

Figure 5.5

6 : How do I optimize the line ?

    Switch to the workstation tab and click on the "Optimize" button. ()

    The optimize dialog box will appear. As you are using variants the slider "MP /Balance percentage" will be enabled. If you slide the thumb to 100 %, the algorithm will try to fit every variant inside the max peak time, if you slide the thumb to 0%, the algorithm will try to optimize the line on average. You can also choose a value between these two extremes. Depending on your licence, you will have to use or not a distant server for computation. If your are using a distant server, you will have to follow these instructions.When the optimization is finished, you will get the automatically balanced line in a new project window.

7 : What's next ?

• You can learn how to use model based variants here
• You can read a page about the general use of the software here
• You can learn about the different operation parameters in this help section
• You can learn about the different workstation parameters in this help section