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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 :-
  • For  those  presses  where  the same  design  is  printed  in  millions  throughout  the  year.
  • The  press  which  is  engaged   in  the  printing   the  same  design  on  long  term  contract  through  the  year.
  • Even  if  there  is  change  in  the  design  it  will  be  effected  only  after  several  days  of  working  with  the  same  set  of  plates/ blocks.
  • Those   engaged  in the  printing  of  Bank  notes,  Currencies,  Detergent  wrappers,  fast  selling  several  Consumer  product  labels  and  wrappers   in several  thousands ,  Raffle  tickets etc.
  • The basic requirement  for  fixing  the  norms  are  that the plant  should  have regular  long  run  print  order   and  not  those  printing  short  run  copies   and  irregular  print  orders. 
  • The  norms  can  also  be  not  fixed  for  those  which  are printing  multi  colour  work  with design change every day.   
The   following  factors  will   determine   the  production  capacity.
  • Rated  speed  of  the  machine  as  suggested  by  the    manufacturer
  • Working  hours  per  Shift – 8 hours  or more
  • Whether  over  lapping  shift  is  in  force
  • No  of  shifts  per  day
  • No  of  working  days  per  week  
  • No  of  days  the  unit  work  per  year
  • No  of  declared  holidays  per  annum
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:-
  • Machine speed as suggested by the manufacturer  : 10000 sheets per hour
  • Working hours per Shift  :  8 hour per shift
  • Whether  over lapping  working  is  in  force : No
  • No  of  shifts  per  day : Two
  • No  of  workmen  per  machine ( This  will be  necessary  to  distribute  the  work  for  faster  moment  of  work )
  • No  of  working  days  per  week : Six  with  weekly  Off  on Sundays
  • No  of  declared  holidays  per  annum  excluding  holidays : 14
  • No  of  days  the  unit  work  per year :
  • Declared : 14
  • Sundays : 52
  • Absenteeism  caused  non  working 15 days  per annum 365 – (14+52) -15 = 284
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.
  • In  view  of  the  above  the   non  productive  hours   per  shift  becomes   approximately 1 hour in  8 hour shift.  Therefore  we  will  have  7  hours  left  for  production  activity.
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  with  minimum  8  times  stoppage  and  restart  of the  machine  per  shift  the loss  of   productive  hours  will further  be  accounted   to  one  to  1½  hour  on  an  average. 
Therefore  we  will  be  left  with  the  following  no  of  hours  for production : 
  • 7 (See ‘A’ above)  minus  further  1½  hour  on  an average (‘B’ above)  leaving 5 hours and 30 minutes  for production activity.
(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:
  • 7 hours (See ‘A’ above) minus  further 1½  hour  on  an average (‘B’ above) minus 10 % ( 45 to 50 minutes)  which  will   work  out   as  4½  hours  for  actual  production .
Therefore  in  4½  hours  the  machine  can  surely  produce  the following  quantity  of  production:
  • 7500 sheets  per hour X 4½   hours = 33750 sheets  or 33750 ÷ 500 sheets  = 67.5 reams  in  ideal  condition . The  67.5  reams  with  40  up  images  will  be   equivalent  to  1.35 million (67.5 Reams  X 500 sheets X 40 Ups = 1350000  ups   or 1.35 million)  per  shift.
Taking  the  above  figure  as  targeted  production  the  annual capacity  can  be  assumed  as  below:
  • 33750  sheets  per  day  per  shift  X  2  shifts  X 40 ups  x 284 days  of  working = 766 millions  rounded  to  750  million  on  the   lower  scale  and  to  800  million  on  an  upper  scale.

    About The Author


    Retired Govt of India Official. My hobby is to write articles that range from Printing technologies to Spiritual.

    Terabyte Vault

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