Conveyors, and more conveyors

Hello,

I am trying to model an assembly line, where the operators make changes to the items while they are moving on a conveyor. Is this possible to simulate in Flexsim?

the only thing I can think of is using a processor, instead of a person.

Hi Davie,

There are several ways of solving depending on the problem. Is the product moving along when it is being worked on? Is it always on the same position when the work starts? Is it really necessary that the operator walks to the product?

I don't know if you have worked with tasksequence already?

Steven

Hey Steven,
Sorry about the delays response, but I've been on holidays and the projects has really gotten under way.

To answer your question, the product moves along a conveyor, and operators pick the items off the conveyor and place them into a tote.
The operator does not necessarily have to move as the totes and conveyor's are within reach.

Thanks,

So If I understand correctly the operator is in a fixed position and picks the product from a conveyor and places it in a tote. I assume that he doesn't has to pick each product that passes?

My suggestion would be that you take 3 conveyors. Make the 2nd one as short as the product and connect if to both the next conveyor and the queue/tote. Then create the right send to port rule and on the use transport select the "Conditional Transport" rule. With that rule you can either select an task executer or not. I use the short piece of conveyor to prevent the operator from walking to the beginning of the conveyor every time. This can also be solved in the tasksequence but this way it is bit easier.

I attached a simple demo model. Let me know if this is what you are looking for.

Regards,

Steven

This works almost perfectly, but i noticed that the operator only picks every second item. So I tried playing around with the condition [port ==1] and the transport [centerobject(current,1)]. If i set the source to create 3 objects [duniform(1,3)], is there a way to get the operator to pick a certain color and place it in queue?

And taking this one step further, if there are multiple operators picking multiple objects, and each object has to be placed in a particular queue. How would I be able to do this?

What I did in the first model I posted was that I connected the short piece of conveyor that is in the middle between the other 2, with the next conveyor and the queue. Then on the sendtoport I used the round robin option which means that he sends 1,2,1,2,1,2,1,2 etc..

Then on the "Request Transport From" option I used the "Conditional Transport" rule. With that rule you can determine if a transporter (operator, forklift etc) is used or not, based on the port(destination) that is selected in the sendto port.

Now to come back on your last question, what you have to do is to connect extra queues, change the sendtoport option so that it selects a certain port(destination) based on the product (for instance with itemtype) and then change the "Request Transport From" so that it uses a transporter if it goes to any of the queues.

If you want to use more than 1 operator, simply connect a dispatcher with operators to the short piece of conveyor. I attached the same model again with the changes. On the exit trigger of the source I create 4 different products by giving them an unique itemtype and color.

Steven

You are nothing short of genius my good sir.

For the condition statement I noticed that you had [port>1] and for the previous example you sent you have [port ==1]. Is there a way to set a range? For example if I wanted items 2, 3, and 4 to be taken off the conveyor, while items 1, 5, 6, 7 would just pass through.

I also noticed that the item stops on the conveyor until it is picked by the operator. Is it possible to specify a wait time? So that, if by 2 seconds if the operator has not picked up the item it moves to the next conveyor. (My idea behind this is that there will be other operators on the line to pick up any missed items)

Thank you for your kind words!

Concerning the condition. In the first model the statement was not [port ==1] but [port == 2] . So this statement is valid if there are only 2 ports, but if there are more ports and you want to have anything beside port 1 you can use [port>1]

But at the same time it is not that condition that is important because in that statement you just look at the resulting port that comes out of the sendto statement. So as long as the next conveyor is connected to output port 1 of the small piece of conveyor, the statement [port>1] is correct.

If a piece is taken off or not is not determined by the operator but by the small piece of conveyor, because that conveyor determines where the piece is send to and if it is not send to the next conveyor, it is taken off by the operator. So if you want different sets logic to apply you have to look at the send to port. You could for instance use the case statement, or have a large table and look in that table what the destination is or you can have small table and reuse that everytime with using an fmod statement.

Your last question is definitely possible but not by simply clicking or selecting. The problem is that when the product reaches the end of the conveyor, then and there is decided where the next product is sent to. If that is a destination where an operator is needed than a task for that operator is created and dispatched. So if you then decide after 2 seconds that the product has to leave anyway without the operator you have to destroy that task again. Or the other way around you check the status of the operators before you create a task and after 2 seconds you check again.

But anyway both solutions require some programming and too much of my time to create it. Maybe somebody else on the forum has a small model lying around that does what you ask, otherwise contact your Flexsim distributor and ask him for a consult quote.


Regards,

Steven

Thanks for all your help!