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A
Anonymous
April 13, 2010
Question

Cutting stock optimization

  • April 13, 2010
  • 2 replies
  • 5080 views
Hello everybody,

I would need an example of how to make a cutting stock optimization in Mathcad... should be only 1D (length cut optimization). Could somebody give me a hint?
Thank you in advance!

2 replies

A
Anonymous
April 20, 2010
... hmm, the topic seems to be not very popular, or maybe too complex...
P
ptc-13682881-Visitor
1-Visitor
April 20, 2010
On 4/20/2010 7:52:42 AM, Desiv5 wrote:
>... hmm, the topic seems to be
>not very popular, or maybe too
>complex...
_______________________________

To me, cutting stock is cutting the plank,
just cut it to length ... in series.
I know a man who lost his job at the bank,
he was making money for them "cutting stock".
Now he makes their money at home, night shift, no Mathcad.

jmG



N
Ninetrees3-Newcomer
3-Newcomer
April 21, 2010
It is a minimizing problem in linear programming. If x[j are the # of sheets for pattern j, you want to minimize the sum(x[j) where sum(a[i,j * x[j) = b[i, subject to the constraint that x[j >= 0.

I imagine that your LP class is showing you how to set up the matrices so that you can solve A*x=b. This would give you a non-integer solution, though, so you must apply some thought to the solution to arrive at the actual minimum, and then convince yourself that it actually /is/ the minimum. I think that you will find the Wiki "Cutting stock problem" a useful place to begin.

Rich
http://www.downeastengineering.com/
P
ptc-13682881-Visitor
1-Visitor
April 21, 2010
Thanks Rich for the Wiki.

The best for "cutting stock" are the cabinet makers. They all do like I did at the time I had this hobby, they build it first in mind, no paper, no pencils. Not enough cut off to make an omelette. But it also depends the length of the planks. The best length is 7 ft, only very few 8 ft. In that Wiki paper mill example, experienced operators wouldn't waste anything ... no program, no computer. What their computer would do is simply recall the client # and plug in the cutting process if this last one is automated.

What kind of industry is that "cutting stock" about ?


Jean
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