Scrap Loss Project – Pattern Optimizing

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    Carl H

    I am chartering a project to reduce scrap rate due to patterning in our film cutting operation.  Basically, we produce supply rolls of film to “standard” widths and lengths the we “cut” the film to narrow widths/shorter lengths for individual customer orders.  Depending on how we cut the orders, there is often leftover film which is too narrow/short for futher use, which tends to become scrap.
    I am trying to estimate one “entitlement low scrap rate” based on theoretically how much film could be cut for the customer from each supply roll.  Its getting complicated with many combinations of widths/lengths being ordered by film type.
    Does anyone know of literature or software which may help with this “pattern optimizing” problem?  Or has anyone had a similar project and would be willing to share how they approched it.


    Erik L

    Based on certain assumptions that you will need to make you could look to some Monte Carlo simulation tools like Crystal Ball to recommend an optimal solution. 



    Hi Carl,
    This is a typical Linear Programming (LP) or Integer Programming Problem.
    Before starting to cut the new film of a fix size, if you are knowing your requirement(s), i.e. Sizes of smaller films that you require to cut out of it, then you can develop a LP/IP model (which can be generalized on over a period of time). The objective function of the Model whoud be to minimize the scrap loss (May be interms of area of Film lossed in scrap). In MS-Excel, there is a tool available as a part of Analysis ToolPack. “Solver” which solves similar models upto certail extent. (There are many advance tools available in the market to solve a LP/IP Problem). It would also help you understand and learn your problem better. If you go to Tools–Add-Ins, you will see “Solver Add-In” in the Menu, On selecting the checkbox, it will appear in the Tools Menu.
    If you search on these keywords – “Linear Programming” / “Integer Programming”, you will find a lot of literature.
    I was involved in a similar problem of fixing Glass cut sheets on a multi-storeyed building , a big size Glass sheet was bought from the market and few sizes were to be cut from this standard one. Objective function was to minimize scrap loss as well.
    Hope this helps.
    My Mail ids are: [email protected]  /  [email protected]
    Wish you All the best,Kalpan



    I think Erik is onto something.  You can probably gather data on the frequency of your different order sizes and use that to assign probabalities of those size orders to your model.  That way your simulation will provide a range of combinations over various runs, but you will end up with something that is more or less representative of your historical usage.
    Good luck

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