Inter-Ing INTERDISCIPLINARITY IN ENGINEERING SCIENTIFIC INTERNATIONAL CONFERENCE, TG. MUREŞ ROMÂNIA, November 2007.

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1 Inter-Ing 2007 INTERDISCIPLINARITY IN ENGINEERING SCIENTIFIC INTERNATIONAL CONFERENCE, TG. MUREŞ ROMÂNIA, November VBA-EXCEL APPLICATION FOR OPTIMIZED GLASS CUTTING Ioan MOCIAN, Universitatea Petru Maior din Tg. Mureş Horaţiu MOCIAN, Universitatea Petru Maior din Tg. Mureş Key words: optimization, cutting, waste, glass Abstract. This paper presents the results of the research work aiming to find an accessible way to optimize cutting rectangular glass parts. These results were turned into a practical application that makes use of the features that Microsoft Excel and Visual Basic for Applications provide. Besides the cutting algorithm itself, the application uses waste pieces left from previous cut activities in order to increase the efficiency of this operation. Introduction This application was designed for optimal cutting of a set of rectangular glass pieces, called parts, from another, larger piece called sheet. Everything takes place in Microsoft Excel, making full use of its abilities. The software is designed for Microsoft Office, beginning with the 2000 version. It was conceived to easily satisfy the pretentions of those who are working in the glass and aluminium woodworks industry. A good cutting of the parts is a large gain for a company, because the price of glass is very high and each square meter that is saved represents lower costs and higher margins. The application consists of several modules which are linked in a logical chain to fulfill its aim: an input and managing of parts module, a results visualisation module, and a printing module. These are the modules that the user interacts with, but other modules hidden from her are included. The most obvious example is the module that actually does the optimization. In general, the optimization activity follows these steps: The application is started, and the parts are input into the worksheet The optimization process is run Random optimizations are visualised All or some of the optimized sheets are printed The report is printed A new activity can begin Optimizing glass cutting is different from optimizing wood cutting because of the particularities of this material and of the cutting technology. Here are the differences: When cutting glass, the blade has no thickness; Waste pieces cand match parts of a new optimization; Glass parts don t have to respect an orientation of the patterns, as wood parts do; As a result, for glass cutting optimization software, we can create an archive that is able to retrieve ready-made parts. Next, the presentation of the application s modules will follow. Data Input module I-26-1

2 This module takes advantage of Excel s features, the user being able to input the parts both in the traditional way and by pasting them from other worksheets. This fact allows the data to be easily transfered from the client through the use of removable storage devices or . Also, a less qualified employee can prepare the part sets prior to beginning the optimization process. Figure 1 illustrates the UI of the module. Fig.1. Data input worksheet In the upper part of the screenshot, the identification elements of the optimization operation can be noticed: Name of the client, Set, Material, Length, Width and Thickness of the cutting sheet. The layout of the table containing the parts is easy to grasp and it contains 6 columns: No (Nr) - the number of the part in the set (used to identify it when viewing the results); Name (Denumire) - the name of the part, if required; X, Y - length and width of the part; Count (Buc) - the number of pieces from the part; Rotation (Rot) - The value of this field is 1 if the part can be rotated, or 0 if the part cannot be rotated (the pattern of the material must be respected). If the cell is left unfilled, 1 is considered by default Any number of parts cand be introduced in the table. It s not considered best practice to use the full capacity, becuase the time to compute the optimization increases. The recommended value of different parts to be input is between 20 and 30. Every user will be able to feel which is the right ammount of input parts for his computer. If you are experienced in using Excel, you can manage your own archive in another file, and use it to exchange working sets, using the copy-and-paste technique. A set can be chosen from the archive using the Open set (Deschide set) button. When this happens, the parts from the set will automatically be inserted in the table. If wanted, we can add or remove parts, or modify the existing ones. On the right-side of the form, several command buttons are placed. Their action is infered by their name. The Optimize (Croire) button starts the data processing module, i.e. the optimization algorithm. First, the parts archive is searched for any mathcing pieces (successful matches can be viewed in the raeport), and the the optimization process is performed. Result visualisation I-26-2

3 The final ail of any optimization is to produce blueprints of the different variants of cutting plans for the sheet, blueprints that will be used in the real cutting process. It is very important for this blueprints to include all the information required for the cutting. So, after the optimization has been done, we must have the possibility to view the results. The View (Vizualizare) button in the data input module opens another sheet called Blueprints ( Placi ), shown in figure 2, where we can view each cutting plan for the sheet. Fig. 2. Viewing optimization results Figure 2 yields all the information we need, as follows: This is the 6th out of 7 different variants. 1 sheet can be cut using this plan; The dimensions of the sheet are: 1000 x 800; Used material coefficient is 81.33%; The name of the client and of the set; Using the 4 navigation buttons and the combobox between them, we can view every cutting plan blueprint. We can go to the first blueprint, the last one, the previous or the next one. Also, we can jump to any variant using the combobox; The 4 buttons on the right-hand side of the sheet can be used to reach the input worksheet, the main board, the report or the printing dialog; From the legend, we find out that this variant uses 3 parts (1, 3, 5). Their dimensions and count is also shown. The report is the sheet which aggregates the results of the optimization. You can see its configuration in Figure 3. The report can be printed by pressing the Print (Tiparire) button. Usually, the report is placed together with the optimization blueprints in a (physical) file, which is handed to the client. The invoice can also be added to the file, when working with external customers. The other buttons are used for navigating to other sheets: Main board, Input data, Visualization, Archive. I-26-3

4 This report can have multiple uses: Fig. 3. Optimization report Verifying the validity of the input data; Finding out the total number of cut plan variants, and the number of sheets that can be cut for each variant; Finding out the total number of parts, the total cutting length and the optimization efficiency The cutting plan variants can be printed fron the Placi worksheet, by clicking the Print (Tiparire) button. A form similar to the one in Figure 4 will pop up. Fig. 4. Print dialog We can opt for printing the current blueprint, a set of selected blueprints, or all of them. There aren t any preparations that need to be made before the actual printing and any Microsoft Office - compatible printer can be used. After the printing is done, the user is redirected to the visualization worksheet ( Placi ). From here, they can begin a new optimization process, or switch to the main board. Archive The archive was introduced as it was requested by customers that wanted to reuse the glass waste that was piling up and made it very hard to find any reusable pieces. As a result, the parts archive was conceived. The customer cand add any waste part that he or she considers reusable to the archive where it is coded and stored. I-26-4

5 How do you use the archive? Fist, the waste parts are picked up and their dimensions are measured. Then, each part is given an unique identifier code. Next, their location in the archive is coded for quick access. In figure 5, the Archive sheet is shown, listing some parts which were taken from waste. Fig. 5. Archive You can notice that a location can store multiple parts, but in a particular order, in order to be easy to find. The locations can be racks, fragments of a rack, or any other place where you can hold a piece of glass. It is the customer s job to keep this archive update. As soon as an input part is found in the archive, the part is removed from the archive, or its quantity is decremented. If the customer wants to use parts from the archive that have the dimension close to, but no exactly the same, to a particular input part, a maximum allowed deviation can be set (both smaller and greater than the original). This is set in the box illustrated in figure 6. Acording to the values in figure 6, parts which have their dimensions 2 mm smaller or greater than an input part wii lbe taken into account when looking for matches in the archive. Manual editing of blueprints Fig. 6. Maximum allowed deviation box This feature was introduce on customers request, in order for them to be able to intervene in a blueprint with the aim to rearrange the initial cuttin plan. This necesity comes into play especially for the last blueprints, when a manual arrangement of the parts yields a better result. This operation is made by the user after she presses the Modify (Modifica) button, which can be found in the grey area on the blueprints sheet. The parts can be copied, moved, rotated, or deleted. The modified blueprint cannot be saved, it can only be printed. Using Back (Revenire) retrieves the initial configuration of the sheet. How to manually edit a blue print? Modify (Modifica) button is pressed; Now we can select any part, and then we can rotate or move it to any position using the mouse; After all the desired moves have been made, the new layout can be printed. You should notice the fact that we can move a part from one blueprint into another. Usually, parts from the last variant are moved in the one before it. To accomplish this, the next steps are followed: We are viewing the blueprint we want to move the parts from; Click Modify (Modifica); I-26-5

6 Select one or more parts (by pressing CTRL during the selection) Copy the parts by choosing from Excel s menu; Click Back (Revenire) to activate the other buttons; Select the blueprint we want to move the parts to; Press the Modify (Modifica) button to allow manual editing of the selected blueprint; Make a cell active in the free area below the legend; Paste the parts in the current blueprint; Place them as desired, then print the blueprint; In figure 7 a selected part is shown (by clicking on its side). When a part is selected, 8 small dots appear on its sides (for each corner and midpoint) and another, green, allows the part to be rotated. When the mouse is close to anyone edge of the part, the icon will change into a crosshair, indicating that the part can be moved. If the mouse is close to the green dot, the icon takes a new shape which suggests a rotation. It allows the part to be rotated at any angle, but usually it is made at 90 o. The Back (Revenire) button reverts the blueprint back to normal, disallowing the user to make any other changes to the blueprint. Conclusions Fig. 7. Selecting a part This article aims to showcase the possibilities of the VBA language, which is found in many software products, including Microsoft s Word, Excel and Access, AutoCAD or IntelliCAD. Other useful applications of this kind will be presented in the future. We wanted to show that highly sofisticated engineering applications cand be created in Excel, which is not only for accountants, but also for engineers looking for practical usefulness. This application uses an evironment familiar to many computer users, Microsoft Excel, thus making it easy to use, and at the same time taking advantage of its posiibilities for input, archiving and manipulation of data. I-26-6