How is the production capacity calculated ?

How  is  the  production  
capacity calculated ?
 (Written by : N.R. Jayaraman)

What  will  be  the  ideal  production  capacity of  a machine printing  40 ups  per  sheet ? How  is  it  determined ? 

Before we proceed further, be aware that  the norms can be fixed only :-
The   following  factors  will   determine   the  production  capacity.
The  data  shown  under are  only illustrative  for  educative   purpose  to  show the methodology  and figures  not actual  as every unit  will  have their  working pattern. Therefore the working  pattern of  the  press  will have  to  be taken  into  account  before calculating  the actual  figures. Let  us  presume  the  following:-
A)  The  following  factors  will  be  considered  as  non  productive hours :
(1) Make  ready  before  actual  production  that  includes  Fixing plates, loading  of  paper, color  setting, registration  etc  say  about one hour (60 minutes) max. If  the  job  is  of  regular  run  which  is continued  for  few days  without  changing  the  plates  or colors, then  initial  setting  time  which  includes  ink charging, loading of   paper and  other settings etc is 30 minutes
(2)  Machine  to  stop  before  Lunch,  say 10 minutes .
(3)  Restart  time  after lunch say 10 minutes
(4)  Machine  to  stop before  next shift  working  say 15 minutes .
All  these  factors   thus  takes  away on an  average  one  hour  per shift  for regularly  run  work  from  the  shift  hours.
B)  Even  though  the  rated speed  of  the  machine  is  given  as 10,000 sheets  per hour by  the manufacturers  they  are  only theoretical  figures  and  it  will  not  be  possible  to  instantly  start printing 10,000 sheets  per hour the moment  you switch  on  the  feeder.   Every  time  the  machine stops  and  restarts  for some reason  or  the other, the  speed  of  the  machine  comes  down  before picking  up  the  full  speed  on  restart  and  therefore  the  average  speed  will  be  75 %  of  the  rated  capacity  only. accounting  to  an  average  of  7500  sheets  per  hour  on  an  average . 

During  the  process  of  printing   due  to  several    technical   problem s  connected  to  ink,  paper ,  dust, and  colour  adjustments  one  can  expect  the machine  to  stop  at  least  once every  hour especially  on  presses  where  blanket  cleaning  at certain  intervals  will  be  inevitable.  Every time when  this happens  minimum  8- 10 minutes  loss  will  be  there  before  restarting the  machine. 
Therefore  we  will  be  left  with  the  following  no  of  hours  for production : 
(C)  Again  for  unforeseen  activities  like  blanket  change, plate change,  packing  adjustment, machine  break  down  repairs, week end cleanings, week beginning make ready time  etc  another 10 % down  time  allowance  is  added .
Therefore  considering  the  above  we  will  be  left  with  the following no of  hours  for  production:
Therefore  in  4½  hours  the  machine  can  surely  produce  the following  quantity  of  production:
Taking  the  above  figure  as  targeted  production  the  annual capacity  can  be  assumed  as  below: