By Mark Porter
Over the years I have talked to hundreds of Finishers and Binderies about estimating and they all have some method of calculating the time and materials for the various processes found in our industry. Diecutting, Folding/Gluing, Saddle Stitching - they all have theories and logic on the calculations of these processes. But Cutting seems to mystify the majority of companies in the Post Press Industry.
It is an important calculation as you as an industry do a great deal of cutting. You cut sheets that are supplied by the printer larger then you want deal with. For example the printer supplies the sheet 25x38 2up but the first thing you do is cut the sheet to 19x25 1 up. You have to cut board and liner if you perform mounting (Laminating to companies on the West Coast). You cut products in the middle of production runs and if you are a casebinding operations you can cut endleaves and cloth for hard cover books. The materials you cut range in size, thickness, weight and coating. These different factors require more then a $3/M or 4000 sheets per hour type calculations that most post press companies apply.
What calculations can take into account all these factors. I have always looked at cutting as it is done out in the plant. First the operatior takes a lift of paper. The size of that lift will start to determine many of the cutting calculations. The typical lift of paper is 3 to 5 inches for the sake of this example lets assume a 3 inch lift. Next I need the thickness of the sheet I am lifting. This thickness would be based on the sheet of paper I am working with. I must also be aware that if I am cutting a mounted sheet (laminate for our West Coast readers) I would combine the thickness of the paper and the board and maybe the liner if there is any.
For the example lets keep it simple and say we are cutting a 60lb 25x38 Gloss Coated Book which has a caliper of .003. This means that with a 3 inch lift I can get 1000 sheets per lift. But I may want to consider the weight of that lift. A 1000 sheets of 35x38 60lb Gloss Coated paper is 120lbs. Can your cutter operator handle that. If not we may want to consider a maximium weight that can be lifted say 60lbs.
Therefore to date we know we have
5,000 supplied sheets / 1000 sheets/lift * 120lbs (lift wt)/60lbs (max wt) = 10 lifts
We are getting 2 out of the supplied sheet - we may determine that we need 5 cuts (1 each side and 1 to split the sheet ) so we have 50 cuts total. You may want to consider a helper if you have more then say 6 out.
If you have a programmable cutter you may want a certain makeready to setup the program lets say 5 minutes setup + 2 minutes programming per cut. (15 mins)
Plus you will need time for each lift of paper lets say 1 minute to grap, jog and place in cutter (10 min) and time for each cut lets say 30 secs (25 min).
Our calcuation is
Makeready 5 minutes + 5 cuts * 2min = 15min
Lifts are 10 lifts * 1 minute = 10min
Cuts 10 lifts * 5 cuts = 50cuts * .5min = 25mins
Total Time 50mins
Hourly Rate @ $60/Hr =$49.99
If we quoted a 100lb Coated Book Gloss (.005) our calculations would have changed to
5000 shts / (3in lift / .005 = 600 sheets per lift) * each lift would be 120lbs / 60lb limit = 2 is 17 lifts * 5 cuts per lift is 85 cuts so our cost for the 100lb stock is
Makeready 5 minutes + 5 cuts * 2min = 15min
Lifts are 17 lifts * 1 minute =17min
Cuts 17 lifts * 5 cuts = 85cuts * .5min = 42.5mins
Total Time 74.5mins
Hourly Rate @ $60/Hr =$74.49
By placing information like paper calipers, maximum handling weights, pile heights based on sheet sizes, cutter programming times, times per lift and times per cut in a program you can get an accurate cutting time every quote instead of questimates that may end up costing you money.
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