MRP Arguement

[MacWheel99@xxxxxxx]

We 405 CD users have been having an arguement about MRP Reschedule dates that 
perhaps someone else can weigh in on one side or another to help us out.

It is my contention that MRP reschedule dates only blow through the whole BOM 
when there is no firm planned order with a contrary story.

Co-workers are arguing that we can rely on MRP reschedule dates irrespective 
of any dates maintained in Factory orders.

Let's suppose we have a Customer Order due end of October and zero Factory 
Orders released   MRP500+600 regen will blow through BOM & correctly date 
plan that we should assemble the end item (100 wire harness) within a few 
days before the promised ship date, and a few days before that we should 
complete the various sub assemblies (many wires), and some days before that 
we should complete the individual wire leads, and the raw materials should be 
in house perhaps 10 days before end item promised to customer.

If customer order gets changed, so now it is due beginning of October & we do 
MRP500+600 regen, and no orders have actually been released other than the 
original customer order, the reschedule dates will be recomputed on all the 
BOM requirements, recommended shop orders & purchase orders, with the same 
lead time logic, so that if we follow the MRP advised dates then we will get 
the part shipped to customer on promised date with no material shortages & no 
expediting needed.

However, if before the due date on the customer order was pulled up, someone 
had released a shop order due when MRP says it was due, we are now in the 
situation of Customer order beginning of October, shop order that satisfies 
the quantity of the customer order due end of October, with reccommended 
reschedule date beginning of October.

All the sub-components & raw materials needed for that end item have their 
MRP reccommended dates driven not by the customer order, whose quantity is 
satisfied by the shop order that will be a month late, but by the shop order, 
so the sub-assemblies (many wires), individual wire leads, and raw materials 
will all have MRP saying they are due as if the part is not needed until the 
end of October.

So long as the shop order for the part says it is not due until the end of 
October, this situation will not change, because human firm orders trump MRP 
soft dates.

Now if someone does shop order maintenance to make the due date of the shop 
order for the end item in agreement with the pulled up customer order due 
date, then the MRP reschedule date reccommendations will drop down a level & 
tell any orders needed to fulfill that item to be ready in sync with the due 
date that was put in the shop order. 

If there are no released orders, MRP will blow through BOM correctly 
calculating everything we need, to once again be on the correct schedule to 
meet our promise to our customer.
  
If an order has been released on any sub-component with a due date that was 
valid before the customer order due date was pulled up, MRP reschedule date 
reccommends that it also be pulled up, but MRP date projections stop at that 
point & do not suggest that any orders to get the materials that sub-assembly 
shop order needs be pulled up, because BPCS is assuming that we know what we 
are doing & are deliberately firm planning dates other than MRP 
reccommendations.

Am I correct about all this, or are my co-workers correct that in this 
respect I have got it wrong?

Al Macintyre  ©¿©
MIS Manager Green Screen Programmer & Computer Janitor of BPCS 405 CD Rel-02 
running on AS/400 V4R3 http://www.cen-elec.com Central Industries of 
Indiana--->Quality manufacturer of wire harnesses and electrical 
sub-assemblies
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