Cutting list to minimize waste

[TomMasselin]

Is it possible to generate a cutting list to cut bars of steel of certain lengths and certain numbers of bars.

Eg:

15 x length 1533 (piece 1)
123 x length 1234 (piece 2)
54 x length 562 (piece 3)
65 x length 386 (piece 4)
35 x length 1853 (piece 5)
...

Then it calculates the number of bars of stock length 6000 or 12000,... needed and the cutting combinations.
I was looking for an existing solution but couldn't find any.

Thanks in advance,

Tom

[MrShorty]

It seems there have been several cutting stock type questions recently. Here are a couple of tutorials that come up when I search for "cutting stock excel":

One example using Solver: http://blog.excelmasterseries.com/20...aste-with.html
Another from the programmers of Solver: http://blog.excelmasterseries.com/20...aste-with.html

Give those a try and let us know where you get stuck.

[Alf]

I setup a model based on the Excel solver as well as the freebie "OpenSolver".

Think I managed to find all possible cut / length combinations that adds up to a standard length of 6000. Checking the theoretical need of stock rods by multiplying the part
lengths with the number of parts divided by stock rod lengths I got 49.18 as the theoretical number of rods needed so solvers solution of 50 rods seems OK.

The constraint setting "$D$116:$H$116>=$D$118:$H$118" can in this case be changed to "$D$116:$H$116=$D$118:$H$118" and solver will still find a solution.

As I defined excess production as waste changing the constraint setting will not change the total waste. It still will be 4930 and 50 stock rods are still needed but in this
case there is no excess production of stock.

To avoid seeing all 100 rows with cuts I've setup an autofilter on row 14 (B14:K14) and filtered for values greater than 0 in column J. Doing a rerun of solver remove autofilter
first.

OpenSover can be found here: https://opensolver.org/

Excel solver has a bit of a problem with the model, after 10 - 15 seconds it finds a solution but can't decide if this is the best solution so it keeps on testing until
it reaches the max time setting (20 seconds) for this setup. Click "Stop" and the "OK".

The OpenSolver has no problem deciding that the found solution is "OK". It stops after 4 - 5 seconds. Both solutions are identical based on number of rods and total wastage.

The problem with a model like this is that if you change the stock length or parts lengths you will have to rebuild your model. Both a tedious and a time consuming job.
So how many rows with cuts do you need to set up an accurate model? Perhaps finding the theoretical number of rods needed and compare it to the solver prediction. If the difference
difference is acceptable fine, and if not add some more cuts and see if this makes a smaller difference?

Using a stock rod of 12000 would probably require several hundred rows of cuts but how many do one really need? The model I build had 100 rows with different cut but I only
needed 8 cut rows for solver and 5 for OpenSolver but if production pattern was changed the models would need different rows to meet that demand and minimize wastage as well.


Alf

[TomMasselin]

Alf,

The list I've shown was just an example of a list. for every project the list is different. Now I'm using a spreadsheet with only length and stock length and it would be handy if I could ad the number of pieces of every piece. You can check the attachement.

[wncjf0106]

I am Korean.
This is the file I received here before. I'll share it with you.
The data language seems to be Russia.