Special operations

[Former Member]

Hi,

Can special operations be used part of the normal routings? I found that it works but the documentation says that special operations can only be used in special routings.

What is the truth?

We have one operation that is mandatory in part of the product routings and for some of the products it is done occasionally only. I was thinking use special operation for that.

Br,

Pete

[Former Member]

This does not sound as if it working as designed.

I would sugges that you make sure that no hook activities are involved. There is a small chance that the hook activity is having the trouble, not the start itself.

If that is not the case, then look it looks like a bug.

[Former Member]

Hi

No we do not have any activity hooks at that operation.

Br,

Jennsen

Edited by: Hannes Jennsen on May 25, 2011 8:49 AM

[Former Member]

I can't think of a reason why changing the operation type from Normal to Special would prevent start at a step. That looks like a bug.

I would suggest you try this on a new router and on newly created SFC. Perhaps the change after the SFC release causes the problem. We copy some router step values to the SFC on release, but the special flag is not one of them. Perhaps there is some other field that is causing the problem.

[Former Member]

Hi

We created a new special operation SAOI and created new routings with that.

LPR-SPI-SMA-SAOI-SPI-SMA-SAOI-DONE

Now we get occasional errors product not in que to SAOI, product in que to SAOI.

What can cause this?

How to check if the special operation handles as normal in the routing?

I've received 10-15 errors out of ~70 panels. I passed them manually with SFC step status. It will be interesting to see if the same happens on 2nd side assembly (wheter it's SFC related or just plain random).

Br,

Jennsen

[Former Member]

Hi

When we tried to do AOI at 2nd side assembly all products gave the que error. I changed the operation back to normal from special and then we were able to continue production.

Is this working as designed?

Br,

Jennsen

[Former Member]

This is intentional and has been unchanged in the product since the 1.0 release. When a special operation is used on a normal routing, it is treated just like a normal operation. It is only special if it is the first step on a special operation routing.

There are processes in place to handle this when being pulled into a special routing, but nothing exists to handle this kind of movement within a normal routing.

[Former Member]

Hi,

Thank you for the answer that was not very clear from the documentation only.

One question still. Why I cannot just change some existing operation from normal to Special?

I tried that but it ended up to strange error messages

SFC WAOI_001 is not in queue at the operation AOI; it is in queue at AOI (Message 13911)

That happened after I changed the normal operation AOI to special. SFC is started after the change.

Br,

Pete

[Former Member]

Pete

You can include a special operation in a production routing, but I don't think that's what you want to do.

If the operation is only executed sometimes, why not change the "queuing decision" in the routing step to the "Next Operator" (default is "Completing Operator") ? That way the operator that starts it at the optional step will then effectively choose to do the step or not.

[Former Member]

For couple of reasons:

1. that will mess up the WIP figures totally. SFCs will be on both queues and that mean double qty on WIP-

2. We have that operation twice on each routing (AOI after SMA) so that will make a lot of branches

Production flow can be:

SMA-AOI-SMA-AOI-DONE

SMA-SMA-AOI-AOI-DONE

SMA-SMA-AOI-DONE

SMA-AOI-SMA-DONE

SMA-SMA-DONE

and after AOI there is either the next step (good ones) or REP (rework for the failed ones)

That mean we need to setup multiple branches for each routing. I do not like the idea of messing WIP figures.

That is another thing why SAP ME calculates the WIP by the queued SFCS instead on individual SFCs in production floor?

That I have asked but answer from SAP was that it works as it is designed (I think that design is stupid).

B,

Pete

[Former Member]

What then is your proposal to use AOI as a Special Operation?

Is it OK that the SFC is in queue for the next operation, but that may change as it may go to AOI instead?

If so, then AOI should be a special operation on its own simple, special Routing: AOI -> Return to Original. You can include dispositioning here for failures too by router scripts or NC code dispositioning.

Your Production Routing is always SMA-SMA-DONE

With AOI as a special operation, it can pull the SFC from wherever it is in SMA and then return it to its original position in the produciton routing.

[Former Member]

This is okay but in some products we need to have this AOI always by customer request. So it has to be in routing.

I am not sure if it works to have special operation in production routing? I got it working when I made totally new operation. By changing the in use AOI operation to special it did not work. That made me wonder if this is the way to go?

Br,

Pete

[Former Member]

I have a produciton routing

OP1-PMR-OP2

which works OK for me. But there is no value in PMR being special here, The advantage of using a speical operation is that you can pull SFCs from the production routing, then return them.

[Former Member]

I know. The thing is that this operation AOI is machine interfaced with SAP ME. The machine cannot change the operation AOI to e.g. SAOI (special AOI) on the fly. So we want to use the same operation as normal operation and in some cases as a special. And if you have the possibility on the machine to change it from normal to special and we forget to change it to normal when the AOI is on products routing that will not be recorded as done step.

Br,

Pete

[Former Member]

One thing. Seems like special operation turns to normal operation if in production routing?

I added SAOI (special operation) to normal production routing. SFCs in that routing cannot be started to SAOI if they are not in the queue for SAOI. In other routing where SAOI is not present SFCs can be started with SAOI as a special operation.

Is that meant to work like this?

This is exactly what we are looking for that is why I am asking.

Br,

Pete