CellSim.XLS A Factory Simulator on a Microsoft Excel Spreadsheet
by John O. McClain Links: [ Free Software | John McClain's Page | Errors
]
This is the old version, with one process per Machine. For the newer version, click here.
In the example below, U14 and U14b are identical machines feeding a storage area, Mid, with defective output going to another storage area, Scrap. A third machine, gg20, takes units from Mid and completes the process. The model is easily augmented. An element may be copied or changed by double-clicking on it. New elements are added by double-clicking on any empty cell.
Only one process is done at each machine. However, a wide variety of probability distributions can be used to describe processing time, time between failures and repair times.
Simulation results are stored on two worksheets, "Machines" and "Inventory" and displayed on two graphs. Of course, all of Excel's functions and graphs may be used to summarize and analyze the results. Explanations are given on a sheet named "Instructions", and simple help is available in the boxes on the "Model" worksheet.
This is a very simple factory simulator, intended for teaching purposes. You are welcome to use it in any manner, and change it as you see fit. This model comes without any guarantee whatsoever, and is distributed free of charge. It is based on ideas first developed at Cornell in the factory simulation program known as XCELL+, written by Richard Conway, William L. Maxwell and Steven L. Worona, with minor help from me. XCELL+ was the first simulation package with a graphical user interface, and appeared in the early 1980s when even the PC was a new idea.
For an Office 97 compatible version, Click Here
For an Office 95 compatible version, Click Here
If CellSim.xls
Doesn't Work:
Some users find that the buttons in CellSim.xls do not work. If this happens,
Excel has automatically disabled the macros that make it run. To fix this (or
to make sure it does not happen) follow these steps:
1. Start Microsoft Excel.
2. On the Tools menu, point to Macro, and then click Security.
3. Click the Security Level tab.
4. Click Medium. Then click OK.
5. Exit from Excel.
"Medium Security" will cause your computer to warn you when an Excel File contains macros, giving you the chance to disable them if you do not trust the person who supplied the file.
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