Optimizing Cutting List For Least Waste

[sergiu_ciuhnenco]

Hi Guys !!!
I have a global question for excell Gurus , somebody have any IDEEA how is possible to optimize the lenght of rebar for a least waste ?
In my country the standard lenght is 12 meters
For Example I have : 3 position Ø 16 lenght 4 m , 3 position Ø 16 lenght 5 m , 3 position Ø 16 lenght 3 m
the best way it will be to cut from 12 meters 5+4+3
But somebody at building site can cut onother way , which will be uneconomic.
I attach a workbook.
is impossible every time create from bombinations 12 meters lenght but is important to get less waste

[Richard Buttrey]

Hi,

I see Marvin offered a solution in this forum 4 years ago - see here

http://www.excelforum.com/excel-prog...ast-waste.html

I suggest you visit post #4 in that thread.

[Alf]

Looking at your problem one realize that rods longer than 9700 will create “waste” less than 2000 (the smallest size demanded) i.e. so there is no possible combination to minimize wastage.

The problem is then to find all combinations of lengths 9700 and less to minimize wastage.

The good: Solver can find a solution to this kind of problem

The bad: The Excel solver is not powerful enough to do this job but the “OpenSolver” written by the University of Auckland can do this. You download if for free and it integrates nicely with Excel (Google OpenSolver for Excel).

You also need to make a “cutting matrix” for Solver to work with. I have set up one “manually” for rods Ø 16.

The thickness of the cut is not taken in account in my set up. One should probably adjust for that since length of rod is specified down to 1 mm.

Looking at the result “Produced” versus “Demand” (row 215, 217) the production matches the demand up to the Y column. Production (Y215) is 21 but demand (Y217) is 12. Since production of rods 3400 is made on row 21 where 21 rods of 8550 is made as well as 21 rods of 3400 you instead make only 12 rods of 3400 leaving you with 9 “rods” with a length of 3450 that my be used later on.

Similar adjustments will have to be made in columns Z to AD.

Alf

[sergiu_ciuhnenco]

Hi again !!!
I found onother ways to solve the problem ,an Autocad lisp here's a link http://http://www.theswamp.org/index.php?topic=48889.0
Bu
It called "the 1D Cutting Stock Problem"
but now I need help with onother problem . the result it show in text file ,I want to make from it a table in excel
I attach a excel file in wich a begin to do it, you will undesstand the way , but I want if somebody will help to make a universal macro , it will be nice if each diameter will be in separate sheet , for example In first sheet I will paste the text file , enter the macro and each diameter table will be in it's sheet.
Phanks in advance !

[jwebb2020]

May I please have Admin permit me to download the attachments to post #3 and #4?

[Alf]

May I please have Admin permit me to download the attachments to post #3 and #4?

As this is an open forum you don't need the Admins permit to download files, text or images posted.

Alf