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Manual of simul8

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  • 1. General Cable Flexibles Factory SimulationAn Introduction to SIMUL8Daniel W. McGregor & Matthew J. Cain Department of Management College of Business and Economics University of Canterbury New Zealand
  • 2. Introduction to SIMUL8 ContentsWhat is SIMUL8...................................................................................................................... 3 Starting SIMUL8.................................................................................................................. 4 1. Using Help ................................................................................................................... 4 2. Toolbox....................................................................................................................... 5 2.1. Work entry point .................................................................................................. 5 2.2. Storage area......................................................................................................... 5 2.3. Work Center ........................................................................................................ 5 2.4. Work Exit Point ................................................................................................... 5 2.5. Resources ............................................................................................................ 5 2.6. Work Items .......................................................................................................... 6 3. Controlling the machines .............................................................................................. 6 3.1. Distribution.......................................................................................................... 6 3.2. Required Resources.............................................................................................. 6 3.3. Efficiency ............................................................................................................ 6 3.4. Routing in ............................................................................................................ 6 3.5. Routing out .......................................................................................................... 6 3.6. Label actions ........................................................................................................ 6 3.7. Priority ................................................................................................................ 7 3.8. Contents .............................................................................................................. 7 3.9. Graphics .............................................................................................................. 7 4. Getting started.............................................................................................................. 7 5. Example 1.................................................................................................................... 8 6. Efficiencies.................................................................................................................. 9 7. Work Items .................................................................................................................. 9 8. Clock Properties..........................................................................................................10 9. Warm up period ..........................................................................................................10 10. Results collection period ..........................................................................................10 11. Graphics .................................................................................................................11 12. Example 2...............................................................................................................11 13. Results....................................................................................................................13 14. Trials ......................................................................................................................14 15. Routing in and out ...................................................................................................14 15.1. Routing In.......................................................................................................14 15.2. Routing out .....................................................................................................15 16. Batching .................................................................................................................16 17. Travel times............................................................................................................16 18. Sub windows...........................................................................................................17 19. Labels.....................................................................................................................17 20. High Volume ..........................................................................................................18 21. Resources ...............................................................................................................18 22. Groups....................................................................................................................19 23. Change-Over times..................................................................................................19 24. Inputting data parameters.........................................................................................19 25. Exporting data/Results to Excel................................................................................21 26. Visual Logic ...........................................................................................................21 27. Example of visual Logic .........................................................................................21 28. Example 3...............................................................................................................22CASE STUDY........................................................................................................................25References..............................................................................................................................28Authors...................................................................................................................................28Appendix A: Order of Operations.............................................................................................29 2
  • 3. Introduction to SIMUL8What is SIMUL8SIMUL8 is a computer package for Discrete Event Simulation. It allows you to create avisual model of the system under investigation by drawing objects directly on the screen.Typical objects may be queues or service points. The characteristics of the objects can bedefined in terms of, for example, capacity or speed.Once the system h been modelled a simulation can be undertaken. The flow of Work asItems around the system is shown by animation on the screen so that the appropriateness ofthe model can be assessed.When the structure of the model has been confirmed, then a number of trials can be runand the performance of the system described statistically. Statistics of interest may beaverage waiting times, utilisation of Work Centers or Resources, etc. Shalliker andRicketts [2002]. 3
  • 4. Introduction to SIMUL8Starting SIMUL8On starting SIMUL8, the screen below will open.This page will allow you to: - Open an existing simulation that came with SIMUL8 - Open one of your own recent simulations - Start a new simulation.1. Using HelpSIMUL8 has a very good onlinehelp section built into the program.To access this click on the helpmenu on the main screen thenindex or use the F1 key. This willopen an index to all the help Itemswithin SIMUL8. 4
  • 5. Introduction to SIMUL82. ToolboxEach of the sections below 2.1 to 2.6, are basic icons that are used within simulation. 2.1. Work entry point This is where Work Items (Job orders) arrive into the system. How they arrive canbe controlled by the arrival distribution and parameters associated. [See section oncontrolling machines to see how to control]. The Work Items can arrive singly or inbatches (multiple Work items together). 2.2. Storage area This is where Work is held in a queue while waiting to be processed. This gives abuffer for the Working machines to allow them to continue Working. [They are usuallyrequired before all the Work Centers so the Workflow is not blocked; SIMUL8 will showan error if the Work Center blocks the Workflow]. You can control the capacity of theStorage area, the shelf life of the Work Items (How long it lasts) in the queue and how thequeue sorts the Work Items it contains (First in, First out or Last in, First out, or priorityetc). 2.3. Work Center This is where the Work is performed on the Work Items by either machines orWorkers [See section 3]. You control the time and distribution that the Work takes at eachmachine, and can collect a certain number of Work Items from different areas within thesimulation and give probabilities or specific Routing out after processing [see Routing inand out]. Used mainly to change the state of the Work item. 2.4. Work Exit Point This is where the Work leaves the system. There can be multiple Exit points fordifferent produced Work Items, i.e., scrap and finished products or happy and unhappycustomers. Do not get confused between storage areas and finished goods, no Work can beperformed once Item reaches the Work Exit point. These can be used to capture Results forWork Items that cannot join the system if the queues are full. 2.5. Resources These are only necessary when processes at Work stations compete for Resources,such as when there is only one operator for several machines and can only operate one at atime. 5
  • 6. Introduction to SIMUL8 2.6. Work ItemsThese objects are temporary entities within the system. They are processed by the systemand are automatically generated at Work entry points and destroyed once they have left thesystem. It is better practice to have only one type of Work Item with multiple Labels ifmultiple Work Items are required. [See Labels] It is easy to change the appearance to any of the graphics of any of these, refer to the graphics section.3. Controlling the machinesThe machine Title is the title of the machine and ifthere is any Visual Logic code we can refer to themachine using this title. To get to the window,double click on any of the machines or storageareas. 3.1. DistributionControls how the machine operates and theprocessing time. The operation parameters that thedistribution requires will show when thedistribution is chosen. 3.2. Required ResourcesAre the requirements of personal to operate themachine. [See Resources] 3.3. EfficiencyThe percentage of the time the machine is able tooperate and can include more detailed breakdownor maintenance schedules. [See efficiency] 3.4. Routing inThis is where the Work Items come into the machine. When you link other machines orWork storage areas together, this automatically updates. You can collect a certain numberof Work Items from each storage area [see Routing in and out section] 3.5. Routing outIs where the Work Items go after the Work is finished [see Routing in and out section] 3.6. Label actionsIf a particular Work Item has an attached Label, we can dictate what are the processingspeeds are, where the unit goes after, before and during the processing. In addition, we canset or adjust any of the Labels at any stage during the processing at a given machine. [SeeLabels] 6
  • 7. Introduction to SIMUL8 3.7. PriorityIf two or more Work Centers, which are ready to start Work, are competing for Resources,the Work Center with the highest priority will receive the Resource first. Do not get thisconfused with the Routing In and Out Priority Rules, these are different. 3.8. ContentsAt the end of a run, or when the simulation is stopped during the course of a run, we cansee the contents of a Work Center or a storage area. This shows all the Work Items that arecurrently in there and the Labels attached to the Work Items. 3.9. GraphicsYou are able to change the appearance on the screen of the Work Center/storage/Exit/entryby adjusting the graphics. [See graphics section]4. Getting startedThe menu-bar at the top of the screen will include all the pictures below. Run the mousepointer over the toolbar to find out what each button means or below is a simpleexplanation.The speed bar allows you to adjust the speed at which the simulation is running.The Build Tools toolbar allows you to create simulation objects. Click each of them to beable to place them on the SIMUL8 Screen. See section 2 for details on the differentobjects.The route drawing mode enables you to connect two icons. Click on one and drag to theother you want to connect. The Show/Hide button toggles the display of route arrows.The clock shows you how far through the simulation the time is. Double click or rightclick the clock to get to the Properties of the timing.The first icon (left to right) shows a graph of the processing content of the selected WorkCenter or Storage Area over time. The second icon is linked to a spreadsheet whereSIMUL8 can read in or export out to, (Discussed later, [see inputting data parameters andexporting data]). The third is a link to the Results page, and fourthly the dollar sign is alink to the financia l data that can be collected. 7
  • 8. Introduction to SIMUL8 (L to R)Click on the Reset tool to reset the clock to the beginning of the simulation.Click on the Step tool allows you to advance the simulation time to the next event.Click on the Run tool to run and observe the animated simulationThe basic toolbar includes the open icon to load existing simulations. The save icon, tosave the simulation, Print, Undo and Zoom.5. Example 1A Simple example – we will build on this example later on.Step 1: add the Work entry point Double click the icon to be able to open theProperties dialog. This will allow you to change the name and the arrival distribution.Step 2: add two storage areas and link them from the Work entry point. Tolink use the Route Drawing button, and drag the connection in the directionthat is required.Step 3: add the Work Centers after the storage areas and name them in theProperties menu by either double clicking on the Work Center or right clickingor going to Properties.Step 4: add the new storage area before the packing Work area, and the Workarea. Make sure these are connected, as shown and connect them to the WorkExit Point.Step 5: add a Resource, i.e. one operator to Work the two process machines. Addthe icon on the page. Note that the default value for the Resource is 10. Doubleclick to get the Properties and change the number available to 1, and rename asHuman Resource. 8
  • 9. Introduction to SIMUL8Step 6: make the process machines require the Resource, by clicking the Resources tab onthe Properties window of the Work Centers. Click add, then select Human Resource.Repeat this for the other process Work Center.Step 7: to show the titles for each of the storage areas, get the Properties window >graphics > title then tick the tick-box for showing the title.Step 8: to have Work Items already in storage at the start of the simulation, start with 5units in each of the storages before processing. Properties > Start-up> set to 5.Step 9: set the processing speeds and distributions for each of the machines. Work Distribution Mean Standard Deviation CenterArrival Exponential 10 minutes N/AProcess 1 Uniform min = 5 and max = 6 N/AProcess 2 Normal 6 minutes 0.1 minutesPacking Average 10 minutes N/A The example is attached on CD as file example.S86. EfficienciesEfficiency of a machine is the percentage of thetime the machine is able to operate. You are ableto adjust these parameters and the average repairtime, if known, to be able to adjust the operatingtime when the machine breaks down.If a more detailed efficiency or breakdownschedule is required, toggle the “Detailed” radio button. This allows you to change the timebetween the breakdowns and the time to fix the breakdowns. You are also able to specifymultiple different breakdowns by clicking on “more>>”.7. Work ItemsIndividual Work Itemsflow through the WorkCenters in a simulation.Each of these may haveLabels attached. Accessedfrom the main screenunder:Objects> Work Item types.You are able to add and remove the Labels attached to each of the Work Item types [seeLabels]. It is much easier to have one Work Item with multiple Labels than to havemultiple Work Items. 9
  • 10. Introduction to SIMUL8Changing the graphics for each of the Work Items [See graphics]8. Clock PropertiesAccessed from the main screen menus Clock> Clock Properties or double click the clockon the main screen. This allows you to adjustthe units of ‘time- measurement’, and howlong to run the simulation. Note that thedefault Time Unit is minutes, and henceprocessing times etc should be specified inminutes. Default settings start at 9 am and runfor 8 hours a day for 5 days. The Warm Upand Collection Period is discussed below inthe next section.9. Warm up periodThe warm up period is the time that thesimulation will run before starting to collectResults. This allows the queues and themachines to hopefully achieve a steady state(i.e., remove transient bias). If the simulationis set up with appropriate initial values, suchas initial loadings and Work in progress, awarm up period may not be required.10. Results collection periodThe Results collection period is how long thesimulation will run before automatically stoppingwhile collecting Results. The simulation will notstart to collect Results until the warm up period hasfinished as discussed above ; the collection periodshould be adjusted to suit the problem. Be carefulwhat units being used the simulation, i.e., if the timeunits are minutes you should run for (60 minutes * 8hours a day * 5 days a week) = 2400 minutes tosimulate the system running for a week. 10
  • 11. Introduction to SIMUL811. GraphicsUsed for changing thegraphics or appearance ofthe SIMUL8 icons.Double click on them toget the Properties window> graphics. This opens thewindow shown. Bychanging the defaultimage, this changes thegraphic for the machine.You are also able to makethe machine look differentfor each of the possible states the machine is in, by changing the animated images furtherdown on the window.After clicking on changing the image, it opensthe Image dialog box, which allows you to openany of the images stored in SIMUL8 andoutside sources. To add from an outside source,click on “Add from Library”, this will allowyou to insert graphics from any of the drives onthe computer.12. Example 2Including: efficiencies, clock, changinggraphics, Results warm up and collectionperiod.Step 1: add an efficiency rating to one of themachines. Process 1 machine. On theProperties window for the machine, clickefficiency> then make it 95% efficient andto repair to take 10 minutes.Step 2: clock Properties. Clock > ClockProperties or double click the clock on the mainscreen. Make the starting time for each day be 7am and the simulation to run for 5 hours a day.For 5 days a week 11
  • 12. Introduction to SIMUL8Step 3: changing the graphics for theResource. Resource Properties >Graphics > select >Then you are able to select adifferent graphic or add one fromelsewhere in your files or from thelibrary. If you click on “Add from thelibrary” you can select a Worker manor other graphics.Step 4: Results warm up and collection period. Change the warm up period to 30 minutes,so the Results are collected after this period. This should be sufficient time to allow thestate of the system to reach a steady state. Change the Results collection period to the restof the time in the week. (5 days * 5 hours a day * 60 minutes/hour – warm up time) =1470minutes. The example is attached on CD as file example.S8 12
  • 13. Introduction to SIMUL813. ResultsOnce the simulation has been run, you are able to getquick Results on the performance of a Work Center orstorage area, via Work Center Properties >Results Export Results: This tells the Results collection table to record information about this Work Center.Many other Results can be collected from each of the simulations. Results can be added tothe Results Summary by right-clicking on the Results in the Objects Results Dialog Box.The Results that have been set to Results Collection are found on the main screen: Results> Results Summary, shown below.Results > Results Comparison.This returns all the information that has been collected for each of the last 200 runs. If theinformation that you require is not here, you will have to click the export Results button for 13
  • 14. Introduction to SIMUL8the desired machine or area, as discussed at the top of the Results section orResults>Results Summary> Detail, then add the Results that you require.14. TrialsA trial is a series of runs of thesimulation. They are allperformed with the same valuesfor parameters but using differentrandom number streams.Trials > Random Sampling, tickthe ‘Auto-change box’. This putsdifferent random numbers ineach of the runs that you do.15. Routing in and outRefer to the Visual Logic [see section 21] that can be behind the Routing in and out. 15.1. Routing InThe Routing in and out tells SIMUL8 how Work Items should be brought into and sent outfrom each of the Work Centers. Shown below is the Routing in for the process 1 WorkCenter. By clicking in the window on name of the Item where the Work Item is comingfrom, it will be circled on main the SIMUL8 window. There are many available Routingrules, collect is discussed more later. 14
  • 15. Introduction to SIMUL8The following Routing rules are the most common:The priority Routing rule sends all Work Items to the first destination in the list, unlessthis is blocked, in which case the second is tried and so forth.Collect lets you collect a number of Work Items from a number of places, for example youmight want two shoes (one left and one right) to make a pair before boxing them.Passive Routing means that the object does not attempt to pull (for passive Routing in) orpush (for passive Routing out). Work Centers normally attempt to pull Work in and pushWork out when it is complete. [SIMUL8 help]For explanation of the others, use the SIMUL8 online Help [shortcut F1]. 15.2. Routing outRouting out indicates where to send the Work Items after the have finished at the WorkCenter.Circulate is default, the first Work Item will go to the first destination in the list, thesecond Work Item to the second,...., the Nth Work Item to the Nth destination on the list.Label Routing sends Items according to the value of a Label. Click the DETAIL button toselect which Label to use. Items with Label value 1 will route to the first in the list, thosewith 2 to the second route etc. Note that Items with Label value 0 will cause the WorkCenter to block.For explanation of the others, use online help for SIMUL8, [shortcut F1] 15
  • 16. Introduction to SIMUL8 Batching is discussed below More>>, as discussed later, explores the visual Logic underlying the Work Centers.16. BatchingUnder Routing In and Out, we can decide to handle anumber of Work Items as a batch. You need to tellSIMUL8 to group them together by collecting thebatch size for Routing into a Work Center [seeCollect]. Alternatively, by changing the batch size forRouting out of a Work Center, you are able to changethe value of the size to leave a Work Center. TheWork Center routes out a batch of Items that arereplicas of the Item being processed.17. Travel timesYou are able to change the time that it takes totravel between two Work Centers or storage areas.You are able to set all the travel times to zero,when they created. To do this,Tools>Preferences>Distance, then set the traveltimes to zero. 16
  • 17. Introduction to SIMUL818. Sub windowsSub windows help to tidy up the screen and group many WorkItems together. Drag a box around the objects you would like inthe sub-window, right click the mouse button, and choose the“Create Sub-Window” option. You are able to change theProperties of the sub window. E.g., to change the Title andgraphics by right clicking on the closed sub window and going tothe graphics dialog.To open the sub window double click on the icon, to close thewindow click the X in the top right corner.19. LabelsLabels are generally used for two purposes. Firstly to distinguish between different type ofWork Items, e.g. product types, and secondly to store attributes possessed by any WorkItem going through the simulation, e.g. a quantity or length. To create a new Label:Object> Labels> New.The value of a Label is set by a Work Center or Work Entry Point, by using the LabelActions option. Add the Labels you wish to modify and choose the action you wish toperform.The order of initiation of the Visual Logic that can be behind the Label actions, aredisplayed in the table in appendix A. It is important to note when label actions are initiatedif they are required before the processing at a particular Work Center. Multiple WorkCenters may be needed with zero processing times to change a Label before it is processedi.e., dummy Work Centers.After clicking Set to: click on value, to input what value you want to set the Label to. Inthis example, all the Work Items that pass through this Work Center will have a Label ofdistance attached to them, with a value of 500.Work Centers that have the high volume box ticked can make use of the Quantity Label. Ifyou have a Quantity Label, this is a very powerful and reserved Label. Every Work Item 17
  • 18. Introduction to SIMUL8type, which goes through a high volume Work Center, must have the Quantity Labelattached to it. The total processing time for the Work Item will be that specified in the inthe Work Center Properties multiplied by the value of the Quantity Label.20. High VolumeThe High Volume option provided by SIMUL8 allows near identical objects to be handledas a batch rather than as a large number of indistinguishable Work Items. An example ofwhere this feature might be appropriate would be a mail bag containing 200 letters. Insome situations the processing time would be for the entire bag (e.g. transferring from thepost box to a van). Other times it is more appropriate to specify timing for each item (e.g.sorting into destinations). In this case the Work Center High Volume option should bechosen and the specified time will be multiplied by the Work Items Quantity label, a labelreserved specifically for this purpose.When Batching-out from a Work Center, the value of the Quantity label is split over thenewly created Work Items. Using the example mentioned above, if the mail bag passedthrough a Work Center with a batching out of 4, then 4 new Work Items would be created,each with Quantity 50.21. ResourcesA Resource is an Item that is potentiallyscarce. They are often used to modelstaff that are required to run WorkCenters, either to set up a process, or toreset a machine after processing a WorkItem.To add a new Resource, click on the iconin the toolbar, place it in the screen thendouble click to get the Properties. Thisdialog allows you to adjust the numberof Resources (usually people) availableand change the graphics.To enable the Work Centers use the Resources, open the Resources option on theProperties for the Work Center, and then ADD a Resource. This will show all theResources that are currently in the system; if the Resource is not there, you may have toadd it before continuing.You are able to pool Resources togetheras well as make the Resources dependenton shift times, and how many Resourcesper shift. Tick the check boxes on theResource form to pool or make theResources shift dependent.You are able to change the details of theResources in terms of when you requireand release them. Different Work Centers 18
  • 19. Introduction to SIMUL8are able to release Resources that have been required in previous ones. You are also able tochange the nature of how many Resources can be used by a Work Center, this may want tobe used to speed up a processing time if more than one Resources in available.The order of initiation of the Visual Logic that can be behind Resource allocation, aredisplayed in the table in appendix A.22. GroupsA group is a collection of simulation objects, i.e., Work Centers or storage areas. A greatfeature of these is being able to limit the number of Work Items which can be within thegroup. To place Items in a group select them, right click and select either “Add to Group”or “Create Group”.Objects>groups23. Change-Over timesSIMUL8 allows you to have a set up timewhen a new Work Item is loaded. This isgood in a manufacturing situation whenWork Item type (change of Label)changes and we have to have a setup timebefore the next Item. Machine Properties> Routing in > Change Over. By default,there is no change over time betweenWork Items.24. Inputting data parametersA very helpful tool within SIMUL8 is that it can read from and export to an Excelspreadsheet. 19
  • 20. Introduction to SIMUL8Any spreadsheet has to be saved as a *.csv file, so save the Excel sheet and change the filename from *.xls to *.csv. After saving the file, you have to create an object withinSIMUL8, i.e., pressing Ctrl+I to get the information store, and creating a new spreadsheet.This one is called “orders”. Within the open simulation Logic and the reset logic, makesure that you set :Once the file is saved, then you can refer to the spreadsheets within SIMUL8 and as singlecells, i.e., orders[1,2]. The sheet above shows a form that is called “orders” for a particulartype of Work Item and having an attached Label for Quantity.The window beside sets the Label Quantity value for eachof the Work Items to the second column of the above table.Var1 is a counter that is updated with Visual Logic [refer tovisual Logic section] after every iteration of setting theWork Items. Therefore, it sets the Quantity Label of thefirst Work Item to 200, then 300 for the second Work Item,and so on.Another example of using the spreadsheets is shown on thepicture below; it refers to another spreadsheet that is calledparameters. The rate of processing is 1/800 metres persecond, and the cell parameters[3,4] have the number 800in it. This is a very good consistency tool, so that if all theWork Centers within the system change processing speeds,we are able to alter the parameters just within thespreadsheet. 20
  • 21. Introduction to SIMUL825. Exporting data/Results to ExcelResults>Results exportExporting data allows you to send data from all of the runs or trails to Excel to facilitateanalysis. The data that is sent to the spreadsheet is whatever Results are currently beingcollected. [See the Results section]. Make sure that you have the file name of a sheet thatyou are using, with the correct sheer name [default sheet 1]. The Excel spreadsheet mayneed to be open for the export to occur.26. Visual LogicVisual Logic is good for coding complex interactions that cannot be achieved usingstandard drag-and-drop modelling. It is an alternative approach to controlling a model bywriting code as a programming language. The ‘SIMUL8 wizard helps users to write thecommands correctly by building code using drop down menus and lists. Once you becomemore familiar, you may choose simply to write the code manually.All the Visual Logic commands, with explanations, examples and where they can beapplied in a simulation, can be found in the Help menu under Visual Logic. Visual Logiccode is executed when triggered by an event, e.g. a Work Item being loaded into a WorkCenter. It can receive and send signals to all the Work Centers and Resources in thesystem. It can be good for updating counters at given times within the simulation and morecomplicating Routing rules. All the decisions can use information about any of theSIMUL8 Work Items, including counting the contents of a Work Center and current states.The order of initiation of the Visual Logic is displayed in the table in appendix A.27. Example of visual LogicThis example shows that if a storage area has0 initial Work Items, then we set the initialWork Items to the value of row 1, column 1 inthe parameters spreadsheet. If the storage areadoes not have zero initial Work Items, thenwe set all the Items within the storage area tohave a Label of Quantity = 1000. 21
  • 22. Introduction to SIMUL828. Example 3This continuation of the last examples and includes steps for: Sub windows, scheduledbreakdowns, Labels.Step 1. Create a sub windowHighlight the things that you want within the sub window, right click the mouse> createsub window. [See section 17]. Create three sub windows on the example. One for each ofthe Work Centers, with their own storage area within the sub window. The picture on themain screen of the sub window will change. You are able to change the picture and makesure the title is displayed under the properties of the sub window.Step 2. Put a scheduled stoppage for maintenance on the packing machine. Click on detailon open more of the Properties window.Step 3. Add a LabelTo create a new Label: Object> Labels> New. Then create a new Label called distance.Then go into the Properties for the Work Arrivals > Label actions > Add, then add the 22
  • 23. Introduction to SIMUL8‘new’ Label called distance. When back at the actions window, check the radio button forset to: then change the value to a Normal distribution with mean of 50 and std dev of 10.Adding the Label allows information about each of the Work items to be passed throughthe system. If you stop the simulation and check the Work items that are within the queuefor packing at a given time, each of the Work items will have an attached distance withthem. The below figure is of the simulation finished, with two work items in the storagearea before the packing process, with their attached label. The finished simulation is shown on the next page. The example is attached on CD as file example.S8 23
  • 24. Introduction to SIMUL8This is a very brief introduction to the basics of SIMUL8. There are many extracomplicating features behind the world of simulation and this manual only scraps thesurface. One thing that has to be noted that all the actions within this document do not getinto depth with the Visual Logic, this is a very powerful feature and all of the commandswithin SIMUL8 as a whole can be controlled within Visual Logic.For more details and examples, refer to the Online Help within SIMUL8 and the followingsection on the Case Study of General Cable. 24
  • 25. Introduction to SIMUL8CASE STUDY Simulation of the Flexibles Factory at General Cable New Zealand LimitedAbstract of the Problem SituationGeneral Cable NZ Ltd has been investigating changing the layout, machinery and productflow within their Flexibles Factory. However, they are unsure of the flow-on effects ofimplementing these changes. The basis of this project was the construction of a detailedsimulation model using SIMUL8 modelling software, to assist the managers in theirevaluation of alternatives. We illustrate the simulation that was constructed to represent theexpected future state of the Factory and which will allow the managers to make decisionsthat are more informed.The follow examples are interesting techniques that the Authors found while doing theProject for General Cable. This case was in terms of a manufacturing environment andsome terms and practices are specific to manufacturing but the ideas can be appliedelsewhere. 1. Sub windowsA good practice that we found that was that the simulation window does not itself have toshow all the detail in your simulation. With a complex simulation, you may want tosummarise your simulation at different levels and only display the upper levels ofinformation. You can achieve this by creating sub-windows.We had many underlying Work Centres that together represent one actual machine.Therefore, on the simulation window we used a Sub-window to show the machine that waswithin the factory, while the actual Work Centers were contained within it. 2. Resources to stop machinesIf the machine warrants only running for limited periods of time, then it was good practiceto control this by making the Work Centre require a resource. This allows you to controlthe resource and turn these on and off when required. If the Work centre can only run whenit has the resource then it will not run. We controlled this using visual logic code, and 25
  • 26. Introduction to SIMUL8when the job orders ran out, we set the resource for the FWD machine to zero, as shown inthe screenshot above. 3. Using LabelsLabels are attributes possessed by any Work Item going through the simulation. Forexample a certain Work Item can have a Quantity or product type associated with it. TheLabels that we required were; Due date – defined in the month spreadsheet and sets the due date so each of the jobsget prioritised on the coilers and the extruders. Quantity – sets the value for the job on how many metres of the product type the job is.This is a reserved Label, so using High Volume gives the total time for processing. Product type – is what type of product the job is, so the specifics to the processing timecan be set. Routed WD’s – this is used as a Label only for the setups. If the Work Center requires asetup, then the route Label is one value and goes to the setup Work Center, else the routeLabel is the default value and goes straight to processing. 4. Routes for setupsSome machinery required resources during setups but not for the remainder of theprocessing time. Because of this the Work Items must follow a different path when theLabel product type changes. This is done using the changeover option in routing in. Thiscalls the distribution “ChangeOver” [see below VL code] when the Label changes, whichin turn changes the Label Route WDs from 1 to 2. Items are routed-out by Label whichcauses the first item of each type to pass through the “setup FWD X” Work Center, whileall other items travel directly to the “FWD X” Work Center. 5. GroupsAn important feature that SIMUL8 can make use of is grouping items together. This can bea good idea if you need to limit the number of Work Items that can be simultaneouslyprocessed by a set of Work Centers. 6. Dummy Work centres 26
  • 27. Introduction to SIMUL8Dummy Work centres that have a zero processing time can be very useful. When dealingwith Label actions and requiring these to be modified before being passed to W orkCenters, then creating a Dummy Work Center can do this. There are some limitations toSIMUL8, in dealing with certain instances, and sometimes many dummy Work Centerswith different routing rules can overcome some of these. For example, the below diagram,shows many routes into the sort Work Center, that just sorts the Work items and routesthem out by a given Label. 27
  • 28. Introduction to SIMUL8ReferencesGiffin, J. (2003). MSCI 311 Simulation Course Handout. Department of Management :University of Canterbury,.Haige, J.W. and Paige, K.N. (2001). Learning SIMUL8: The Complete Guide. Plain Vu: Bellingham, WA.Shalliker, J. and Ricketts C. (2002) An Introduction to SIMUL8, Release nine. School of Mathematics and Statistics, University of Plymouth.SIMUL8 Help (2003) Retrieved October 2004. Release 10.0 softwareSIMUL8: Manual and User Guide. Visual Thinking International: Mississauga, Ontario Canada.___________________________________________________________AuthorsDaniel W. McGregor Matthew J. CainDepartment of Management, Department of Management,University of Canterbury, University of Canterbury,Private Bag 4800, Private Bag 4800,Christchurch 8020, Christchurch 8020,NEW ZEALAND NEW ZEALANDEmail: Email:dmc89@student.canterbury.ac.nz mjc181@student.canterbury.ac.nz 28
  • 29. Introduction to SIMUL8Appendix A: Order of Operations.This table shows the order of events that occur during processing at a Work Center(from Haige and Paige, 2001). It is important to be aware of this sequence when relyingon changes to label values to control the model. Make sure that any necessary changesare completed before the dependant decisions are made. Direct Work Center Sequence Distribution Pre-Sample Recommended Uses Sections Routing-in before(if Examine conditions in the model. Work Center is idle, this Select and examine a specific section will be called Work Item. Set Routing-in after each event in the conditions s uch as batching-in or 1 simulation) collecting rules Examine each of the Labels and current model conditions to determine processing time. Update After loading Work other model conditions when a new Work Item is moved into the 2 Work Center. Examine Labels and current model Change Over conditions to determine processing 3 time Examine Labels and current model Process Time conditions to determine processing 4 time Determine Routing-out discipline, Work Complete set Labels and batch sizes. Update 5 result statistics Batch Size Examine Labels and current model 6 conditions to determine batch size. Set Label to a distribution Adjust parameters of the vale ( repeated for each Item distribution based on conditions in 7 in batch) the model Label Actions ( repeated 8 for each Item in batch) Set Label values Before Exit ( repeated after each event while Execute code to check for and/or 9 Work Center is blocked) handle downstream blockages On Exit (after all Update inventory calculations. Set Routing out decisions individual Label values across a 10 have been made) batch. 29
  • 30. Introduction to SIMUL8 Department of ManagementCollege of Business and Economics University of Canterbury Christchurch New Zealand http://www.canterbury.ac.nz 30

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