Linear programming production setup time

[Olainium]

Hello guys!

I am in a struggle with a solver problem. I am unable to figure out how to define the constrains needed in order to define the follow;

If product 1 comes before product 2, then setup = x
If product 1 comes before product 3, then setup = y
If product 1 comes before product 4, then setup = x

The problem comes from a production process where I wish to minimize the setup time by rearranging the production scheduling.
I usually use this forum when I have hit a wall in regards of excel - which, by looking at my profile doesn't happen very often.

I hope you can help me.

Best regards,
Olainium

[bebo021999]

How to define whether product "1" comes before product "2"? and how to say [ set up ="x" ]

Please attach a sample workbook (not a picture or pasted copy)
Click on GO ADVANCED and then scroll down to Manage Attachments to open the upload window.

[Olainium]

Hi bebo021999,

I just realized I posted this threat on the wrong forum - it should have gone into Excel Programming. I hope someone can transfer it.

To answer your question;

I have a total of 80 items each with different run-times but with very similar set-up times.
When I run product 2 after product one I have to clean for 4.5 hours, whereas if I run product 3 after product 1 I have to clean for 3.5 hours due to product family definitions.

I am currently unable to upload a sample. Will do so when I return home in a few weeks.

[Alf]

From your short description I would treat this problem as a "travelling salesman" problem as the the setup order seems to be the most important factor. So instead of distance between cities I would use the time between the different choice of jobbs.


Perhaps this link may be of help:

https://www.youtube.com/watch?v=-E3rSoClgMI

Alf