We have just installed Aurora 2.2 and we are implementing the
manufacturing system but we have a problem with overlapping operations.
We fuse quartz and currently we create one works order to produce say 12
tonnes of Quartz and each piece that comes off (roughly 500kg) is given
an unique lot reference. The routing looks like this....
Op 10 Build Furnace
Op 20 Light Furnace
Op 30 Warm Up period complete
Op 40 Fuse
Op 50 Anneal
Op 60 Inspect
Op 10 Takes 2 days - one occurrence
Op 20 Is used to give us a date that the furnace is lit - one occurrence
Op 30 Warm up takes 8 days - one occurrence
Op 40 Fuse ingot. An ingot is produced every 2 days and weighs about 500
kg. From a run we expect to create about 24 ingots.
Op 50 Anneal an ingot - for each ingot fused (2 days per ingot)
Op 60 Inspect - for each ingot annealed.
Normally when running works orders through MPS it is assumed that each
operation follows in order. In our case operations 10 - 30 are done in
sequence and only once. However, we fuse an ingot every 2 days and as
soon as the first ingot is produced we want to start the annealing
operation and as soon as an ingot is annealed we want to inspect the
ingot and receive to stock. Operations 40 to 60 are repeated for each
ingot.
If this order ran in sequence then the works order would take 2 days + 8
days + (24 x 2 days) + (24 x 2 days) = 106 days. In actual fact it takes
considerably less because the annealing operation starts as soon as the
first ingot is receipted against operation 40. Therefore the actual time
taken is 2 days + 8 days + (24 x 2 days) + 2 days (last annealing
staggered operation) = 60 days.
Looking at the manual says that there are 2 ways of staggering the
operation. 1) Overlap delay, 2) transfer batch size. Overlap delay means
the second op will be available to start continuous process after a
stated number hours, transfer batch size means that the second operation
will be available to start when at least the 'batch size' has been
booked from the first operation.
What we are actually getting is that the overlap is being measured from
the end of the 1st operation and not the start.
On a simplified version of where a fusion takes 2 days and annealing
takes 2 days and we expect to get off 3 ingots @ 1200m I would expect
the order to take 6 days which it does and the annealing option should
start on 27/05/08 but does not.
Here it shows that the annealing operation starts 2 days before the end
instead of 2 days after the start.
Can anyone shed light on this please?
Apologies for the size of the email.
Alan Medows
IT Manager
Saint-Gobain Quartz Ltd (Registered Company No. 00089761)
Tel: +44 (0) 191 259 8412
Mob: + 44 (0) 791 739 6412
Fax: +44 (0) 191 263 8040
mailto:alan.medows@xxxxxxxxxxxxxxxx
http://www.quartz.saint-gobain.com
midrange.com
