How to correct scrap quantities when by mistake the quantity is reported wrong at the first time.

[Former Member]

Let us consider a sample route containing Step1 to Step 10.

When an SFC: SFC_1 with 250 PCS has an NC of type Scrap reported first time manually at Step6, then the left over quantity on SFC_1 is 240 PCS.

The completed Quantity on SFC_1 from Step6 until Step10 will be 240 PCS and assume that the SFC is currently in process at Step9

At Step9, if the operator recognizes if the Scrap Quantity at Step6 is 20 PCS instead of 10 PCS (by mistake user didn’t report the other 10 PCS), then what are the various possible ways to correct the Scrap Quantity in order to have the right Yield and NC Log data at the subsequent operations.

If we choose to perform a SFC Step status on SFC_1 for 10 quantity from Step9 to Step6, then you can have 10 PCS available at Step6 and a NC of type scrap can be registered so that the NC log looks accurate.

But with this the Yield by Operation which is based on the completed quantity at an operation goes wrong, because the Step6 has 230 PCS completed, whereas, the intermediate operations Step7, Step8 has 240 PCS completed.

So how can we correct the Scrap Quantity (From Low to High) without affecting the Yield By Operation calculations ?

Thanks,

Henri

[sergiy_katerinich · Accepted solution]

Hi Henri,

After returning the SFC to Step 6 by means of SFC Step Status, this will be the second pass through the step which does not change the original numbers of the first pass of Yield by Operation. It should appear in Re-test columns rather than changing First Pass value of the report.

Regards,

Sergiy

[Former Member · Accepted solution]

Thanks for the quick response Sergiy.

Still one issue :

If the system considers processing those SFCs for the second time on those steps (Step6, Step7, Step8 in our example) as Retest due to SFC Step from Step9 to Step6, then the First Time Wrong calculations results in a high value, because all these quantities processed first time will be automatically considered as First Time Wrong, even though they are First Time Pass actually.

Thanks,

Henri

[sergiy_katerinich · Accepted solution]

Hi Henri,

I guess that Yield report does not have such notions like "wrong pass" or "correct pass" but rather compares passes with non-conformances. Those once look like your personal interpretation of numbers just because you do know the scenario. If there were a number of different patterns of processing SFCs through the operation, you would not have any feasible way to figure out what went "wrong".

The principal issue is that you take SFC Step Status as a normal production activity whereas it is not - on the contrary, the fact that you have to use this activity means that you have had some problems in production. And those problems are causing some increase in Retest numbers. Normally, in production this activity is prohibited, but could be used by administrators only as the last resort.

Regards,

Sergiy