"How does the process work...?"
In my MC the Part Time (evening) staff are usually on the culling, facing and sorting.
The mail is collected from firms, pillar boxes and Post Offices by drivers.
Brought into loading bays/platforms where it is unloaded then taken into the processing area by platform staff.
The mainly stamped letter mail from pillar boxes and Post Offices will to to the CFCs for facing and cancelling.
Stamps on packets and flats are cancelled by staff with hand stamps.
The meter mail (mail from firms that has been through a franking/meter machine) is tipped onto facing tables.
Staff on the facing tables seperate it into first and second class.
They also seperate out the flats (large envelopes) and packets.
The flats can be sorted on large flat sorting machines, or by hand.
The packets are mainly sorted into bags on drop bag frames (dbf's).
The letters are seperated into those which can be sorted on the letter sorting machines (lsm's),
and non-machinable which will be sorted manually.
The manual letters (and flats/packets) then go to primary sorting.
Some can be despatched directly from primary sorting to the Mail Centres or Delivery Offices from where
they will be delivered.
The rest will go to secondary sorting areas for different parts of the country (Scotland, Wales, N. Ireland,etc)
where they will be sorted to cities or mail centres covering different areas, where they will be sorted and
sent to local Delivery Offices.
The machinable mail is sorted on Optical Character Recognition machines which can read addresses and
postcodes and imprints the letter with a series of blue phosphor dots which can be read by the Letter
Sorting Machines (LSM's).
The coded mail is then loaded onto a LSM which sorts the mail into boxes for the local Delivery Office.
The sorted mail is tied up in bundles and thrown into bags for despatch to the Delivery Offices, or
Mail Centres covering that area.
There are now newer machines - IMPs and MTTs which I don't know much about as it's over 20 years
since I worked in the Mech Area, but I expect TMan or some of the mech guys on here might tell you
about those.
The bags are tied up and taken out in wheeled containers (Yorkies) to the despatching bays/platforms,
where they are loaded onto lorries to be taken to the Mail Centres/Delivery Offices from which the
mail; is to be delivered (But that's another story!).