Optimizing Cutting List for Least Waste - With a twist!

[alamedapipe]

I have a more complex problem than the standard cutting stock problem here. Wondering if you guys can help me out. I have a list of around 180 pieces of pipe ranging in length from 35ft to about 44.7ft. I need to cut and weld pieces together to make 52ft lengths.... Heres the catch; can't use any piece shorter than 3 meters. I need to end up with 49 finished parts total. Can anyone here help me to solve this problem with excel? I have a stock list of sizes in excel.

Thanks in advance! This would be a HUGE help!

Chris

[pjwhitfield]

In your example the biggest 43 lengths are too long to use in their entirity ie the length needed is less than 9feet. The code below therefore runs from the biggest lengths down from this and cuts the required length from these at each stage. Im fairly sure that with some additional work and sorting etc then you could get some more lengths calculated however this one creates 129.

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[alamedapipe]

Is there a way to get that code into excel with cell manipulation or formulas? I'm not familiar with the scripting...

Thanks!
Chris

[shg]

See the workbook at https://app.box.com/s/7bsmo5e6izk346v5p5vv

[alamedapipe]

Wow thanks, that workbook is very useful. How could I get it to minimize the waste on cut pieces thats shorter than x feet?? I ran a few tests with the spreadsheet and it gives a way to make each finished part properly; but does not seem to be doing it with the least scrap possible...
Thanks again, super helpful sheet we will be using this a lot!
Chris

[shg]

but does not seem to be doing it with the least scrap possible...

For example, ...?

[alamedapipe]

We did this problem out by hand just picking/choosing like a puzzle (took 2 hrs or so) and came up with 28ft or so of scrap. The shortest length is 3m which = ~9.9ft roughly. The solver spreadsheet came up with much more total cut waste like 36ft. <20 ft lengths are pretty much unusable for future jobs and the material is expensive. Is this algorithm solving for least amount of scrap? Maybe we did something wrong on our hand calculation
Thanks in advance,
Chris

[shg]

From the original problem statement shown in the workbook,

We only want one mid weld if possible on each pipe and we would prefer it to be at least 3.3 feet from the end of the pipe.

... the code is designed for fabrication with a single weld only.

It would have to be modified to allow fabrication from three or more pieces.

Why are you using a mix of meters and feet? The workbook assumes all lengths are in common units.