How to solve this scheduling problem using flexsim?

Hi All :

i'm trying to sovle a scheduling problem ,but i don't have any idea. There are six machines , their Takt Time is: 80 seconds, 40 seconds, 40 seconds, 40 seconds, 40 seconds,40 seconds . A operator carries products from raw materials to processing on the machine. Every time the carrying amount is 20 . At the beginning each machine already have a certain number of products : 10 20 20 20 20 20 .

so, how to determine the transport interval of the operator , to make the WIP lowest meanwhile the machine won't goes down .

I would really appreciate any input! Thank you very much.

Why did no one give me a reply? Did I didn't describe the problem clearly?

Hi, I think you should describe more exactly what you are looking for.
What I understand is, that at the beginning of your model first machine has 10 products and all others have 20. Because your first machine needs 80s for 20 products process will be finished at the very same moment as all other machines.


So what do you want to know?
The question you asked could result in different beginnings:
1. Put queues infront of the machines. So the Operator can do transport while machines are running.
2. Set different starting times for machines, so only one machine will wait.

hi Sebastian :

Thanks for your reply. Sorry for my poor English ,i'll try to describe more clearly .

As you see , there are 6 queues before the 6 machines. At the beginning of the model , the first queue have 10 products(item) and the other queues have 20. The first machine need 80s to process one product (item) and the other 5 machines need 40s to process one product(item) . So they all need 800s to finish the process.

The operator is only responsible for transport product(item) from raw material to these 6 queues. And each time , the operator must transport 20 products(item).

Now i want to know how often the operator transport products. eg: Every 100s the operator transport products to these queues , the machines will never stop . But as the model running , the products in these queues will be more and more . If every 600s the operator transport products to these queues , the products in these queues will be very litter ,but maybe some machine will stop (wait for item) which is not allowed in this model .

So how to determine the time interval to make the products in these queues as litter as possible meanwhile the machine will never stop(wait for item) ?

I'm not sure i describe clearly ,if not ,let me know .

Thank you very mush !

Hi Jay,
so what I understand is, that your Operator is able to carry 20 products and you only want to know, how often (possibly also when) he has to do the Transport.


What you can do is to look for the filling in your Queues and influence this.


My idea would be to build a source and a (Source-) Queue which supply the 6 Queues and only measure how often this Sourcequeue released items.
Then you can calculate the average or show absolute expression as tracked variable.