Non Accumulating Conveyor Blocking Itself

[HermiasH]

Good day

I am busy trying to figure out the reason for the following: (Model attached)

• There is a closed-loop non accumulating conveyor belt with different colour entities arriving at Negexp 0:27.6. 
• When the colour reaches its matching station it is offloaded only if there is capacity. If there is no capacity the part simply loops around and tries again.
• The conveyor has a capacity of 8

With the initial simulation the following occurs:

As the one part tries to access the conveyor it causes a grid-lock.(Conveyor Blocking itself)

If the simulation is run with Accumulating active the following occurs: (Basically the conveyor blocks itself)

If for example I add a "Loading Line" then the same gridlock occurs:

Any suggestions of how to get around these issues?

Regards,

H

[KarolaMock]

Hello

non accumulating: the conveyor stops when one part on it stops. So the blocking situation happens when during the entrance of a MU another MU at the end of the conveyor will enter the conveyor at the begin again. Because the entrance is not free this MU will be stopped and also the complete conveyor. You should allow a new MU to enter the conveyor only when it can completly enter the conveyor before a MU reaches the end of the conveyor.

capacity: all MU-parts were counted for check of capacity. When 8 parts are on the conveyor the part at the end cannot enter the conveyor at the begin because then there were 9 MU-parts on it.

Regards

Karola

[HermiasH]

Hi Karola

Thank you for the reply.

I understand what is causing the blockage; I'm just not sure how to get around it exactly.

For example. See below the following case:

1. Non accumulating conveyor (capacity = 5)
2. source creates 5 entities only
3. once the entities reach the end of the line they cannot continue in a continuous loop  (Like a baggage conveyor at the airport) They are blocked because the Line's capacity has been reached and cannot accept new MUs, even from itself

Any ideas of how to get around this?

Regards,

H

[cmcdonald · Accepted solution]

Hi Hermias

There is an easy fix to get past this problem. Draw a small extra part of the conveyor and connect this between the end and beginning part of your big conveyor:

 

In your source create a front exit control:

This will ensure that no two parts would want to occupy the same space and your conveyor wont get blocked.

Regards

Chrisni