How does a CSS machine work?

[datasaint]

I understand it uses optical recognition to read the addresses, but how does it sequence an entire walk? Do the letters get stored in some kind of holding bank which the machine can extract specific letters on command to place in sequence?

[Spedley]

I'm not sure of the sorting algorithm they use but it goes a little something like this ...

1. You empty the trays of letters in a long line which then slide flat-face forward into the machine.
2. The machine then reads the red barcode (which has previously been printed at a mail centre after OCR) and send the letter to one of several output slots (e.g. first delivery points at the left most slot and last delivery points at right most slot)
3. You then feed all these slots of mail back into the machine in order until it has completely sorted it (as per No. 1)

You may want to look up 'selection sort' as a sorting algorithm which is probably something similar.

[blue1873]

Dont know the why's and wherefore's of the CSS machines but i do know
that the mail has to be run through the machine three times whilst an
ILSM does the same job in only two runs, at our MC we have one ILSM
standing idle for a full shift while all our CSS machines are running,
seems like economic madness to me.

[SpacePhoenix]

Dont know the why's and wherefore's of the CSS machines but i do know
that the mail has to be run through the machine three times whilst an
ILSM does the same job in only two runs, at our MC we have one ILSM
standing idle for a full shift while all our CSS machines are running,
seems like economic madness to me.

Why don't they use the iLSM that stands idle to sequence mail for the largest DOs covered by your MC?

[glenfiddich]

Dont know the why's and wherefore's of the CSS machines but i do know
that the mail has to be run through the machine three times whilst an
ILSM does the same job in only two runs, at our MC we have one ILSM
standing idle for a full shift while all our CSS machines are running,
seems like economic madness to me.

Why don't they use the iLSM that stands idle to sequence mail for the largest DOs covered by your MC?

now now spacephoenix we'll have none of this common sense approach to working in royal mail

[Tman]

Why don't they use the iLSM that stands idle to sequence mail for the largest DOs covered by your MC?

Probably because the duty times, machine run times and maintenance periods are set up for the iLSM to be "idle" at those times.
Possibly because questions would be asked about how those very expensive CSS machines weren't being sufficiently utilised, and
would you really want to see those CSS operators out of a job?

[blue1873]

Why don't they use the iLSM that stands idle to sequence mail for the largest DOs covered by your MC?

Probably because the duty times, machine run times and maintenance periods are set up for the iLSM to be "idle" at those times.
Possibly because questions would be asked about how those very expensive CSS machines weren't being sufficiently utilised, and
would you really want to see those CSS operators out of a job?

Sorry Tman dont think it's got anything to do with your possible reasons, there is one machine
lying idle all the time with the exception of when there is a major breakdown.Management
had originally intended putting in SIX ILSM's despite telling everyone for years that mail volumes
were/ are in decline perhaps it was a good job they only went ahead and installed FIVE ILSM's,
saved themselves a few bob with that decision.Words like piss up and brewery come to mind

[Budfrog]

If you can weed out the BS and the info that is now well out of date this gives a reasonable insight:

A day in the life of a CSS operator (there may be minor variations from region to region in attendance times)


I work from 1130pm-0930am for 4 days a week as a Compact Sequence Sorter (CSS) operator in a Mail Preparation Unit (MPU) A MPU is the new name for my Delivery Office now it has CSS machines. Before I got this job I used to do delivery and collections in the DO.

There are three CSS machines in our MPU and by the time I arrive, the first Yorks of mail have arrived from the mail centre and there is mail waiting for Machine 1 which is the machine I will be operating. This first mail to be processed is known as Wave 1 and about 60% of the mail to be sequenced arrives in time for Wave 1. Any mail from the network and the rest of the available mail comes in during the night to be in time for Wave 2 which we start around 0600 when we run the whole process again.

The first thing I do when I arrive is tuck my ID into my shirt so that it wont get tangled in the moving machinery and then I start to segregate the trays into the correct Yorks for each batch that will run on this machine. A batch is all the mech letters for around 10-12 walks. This covers about 6000 delivery points. The volume of mail will vary on a daily basis but normally at night it is about 20 trays which is about 5500 letters. As well as sequencing mail for our office we also do batches for some of the other delivery offices nearby.

Just before midnight I turn on the machine. The CSS runs an automatic machine health check which checks the systems and makes sure everything is working correctly. It also alerts us if some new sort plans have been loaded automatically by the mail centre.

While the machine is doing this I start to load the first five boxes of mail on to the feeder belt using the safe loading process I learnt on the training course. The three day training course assumes you have no previous experience of machine operations. They teach you the safe and efficient way to operate the machine and you have time to practice with test mail before you use live mail. We are also trained how to do the daily maintenance tasks known as Total Productive Maintenance (TPM). TPM involves cleaning and checking a number of vital machine components which is a really important part of our job because if it is not done correctly the machine will not perform at its expected level and customer’s mail may get damaged. Even after the training, it still takes around six weeks of actually doing the job before you are working efficiently and it becomes second nature.

Once I have loaded the first boxes onto the feeder, I make sure it is stacked evenly and then start the machine before loading the rest of the trays. The machine processes the mail at a rate of 40000 letters per hour but it takes three passes through the machine to sequence the mail and part of the time the machine won’t be running whilst I am re-feeding between passes, so the planned rate for sequencing is 9000 items per hour. Whilst the machine is running I go and print a set of tray labels for the batch on our label printing system. During the first pass I put the blue and yellow separator cards in with the mail. The computer screen tells me how many are needed but I put a few extra in just in case any are rejected. These cards stay in with the mail through all three passes and at the end of the third pass will mark the end of the sequenced delivery points for a walk and then the end of all mail for a walk. (Some mail cannot be sorted to delivery point order because some information is missing on the code mark but can still be sorted to a postcode which means it is still in the correct walk).

Every now and then the feeder jams due to a letter being unsealed or torn and I have to hit the emergency stop button on the machine and clear the jam. This normally only takes a few seconds but we are always looking for ways to reduce the jams as any slight stop in the process slows us down and we have distribution times to meet. Occasionally the stoppage is more serious and we have machine down time. If it is a small break down I have TPM allowance and training which means that I can change belts and fix the machine myself, if it is outside my area of responsibility I can call an engineer who is usually no more than an hour away. If the machine were to be out of service for the rest of the night we have to use the other machines to walk sort mail if we run short of time by just putting mail through one pass.; but this rarely happens.

When all the available mail for the batch is loaded I add the green cards which will pass through to the stackers to mark the end of the pass. If the batch I am running is quite large, I have to move some of the letters to prevent the stacker full system stopping the machine. There is a warning light above each stacker but as I have been doing the job for a while I know when this is going to happen and we normally twist the mail at the front of the stacker around and place it in front of the paddle to create more room. When the feeder runs out of mail and the green cards have been fed I can start re feeding for the next pass. Starting from stacker one I then clear each stacker box in order. When stacker 19 is cleared I take out the green cards and place them at the back of the mail again. I repeat the process for the third and final pass through the machine, and when the green cards finally feed into the stacker boxes that means the batch has finished and all the blue and yellow cards are in the right place to show where the walks end.

I then clear down the first 12 stackers and load the first five trays from the next batch and get the machine going again to save down time while I finish off the clear down. You have to keep concentrating on this job because if you get it wrong the whole batch is messed up and it has to be started again.

At any one time there is only one of us on a machine and we operate it for about 2 hours before another operator takes over. We always finish the batch we are working on before we have a break otherwise mistakes can be made. We then help unload Wave 2 mail and seg it or do some packet or flat sorting depending on what is needed if we are not due a meal break.

There is some paperwork to do, mainly filling in information on to the performance sheets to show when the machine started and stopped, any breakdowns or jams and how long they took to clear. We can then calculate how efficiently the machine is processing. We measure the performance using Overall Equipment Effectiveness (OEE) and we are encouraged by our manager to think about how we could make the process more efficient. It is really satisfying when you come up with an idea to save time, your idea is trialled and it works. We want to be one of the top teams of CSS operators so even little improvements make a difference.

At the end of the shift as part of TPM we have to visually check and clean the machine to keep it working well which takes between 15 and 30 minutes with a vacuum cleaner and some special brushes.

I hope you found my day interesting. I think you can see to do this job you need to be physically active, happy to work on your own and organised. We like our shift pattern as we work four 10hr nights on in a three week rota which means every three weeks we get a five day break which is really nice.