A major factor in profitably running a flexographic press is keeping the amount of material waste to a minimum. An excellent means of reducing waste on a standard flexo press, especially when printing on expensive substrates, is to use a servo infeed and re-register system such as the easily attached Servo 3000 Digital Infeed + Re-register system made by Rotary Technologies.
An ideal system, such as the easily attached Servo 3000 add on will bring the print job in register in one length of the press, the absolute minimum of any press. With every stop and start of the press the Servo 3000 saves substrate and saves money. When printing on expensive substrate such as BOPP (bi-axially oriented polypropylene) films the Servo 3000 will keep the job in register despite the normal stretching and shrinking that takes place when printing on films. Using the Servo 3000 the job will require fewer stops for adjustments as well. The sum total material waste saved could come to as much as a quarter of all the material on a roll.
BOPP Films
BOPP films are designed for flexible packaging and labels. This polypropylene product is inert and therefore not affected by most common chemical agents. BOPP films are non-toxic and can be recycled. These features along with high tensile strength, clarity, and resistance to water passage make it popular. For the flexo printer a major factor is the printability of BOPP films. They can also be treated to make them more sealable and better barriers using acrylic and PVDC coatings. In short this is a great material for packaging and labels. However, it is also somewhat expensive.
A recent search of the internet for listed prices for BOPP film shows that 2.6 mil white BOPP TC is selling for 0.400 per MSI. A 6 ¼ inch roll, 7,800 feet long currently sells for $234 plus shipping and taxes. For the sake of the following calculations for printing we will only consider the material cost of $234 a roll.
Savings Example
The length of material in a twelve color press is 200 feet. Besides the initial start the press will be stopped twice to rewind and remove printed material. It will be stopped twice for adjustments. Assuming that labels are being made, two stops will be required in addition to remove waste matrix. This will come to 1 + 2 + 2+ 2 = 7 starts of the press.
We will assume that it takes two lengths of the press to get the web in register with each start. This will amount to 400 feet of waste material with each of seven press starts or 2,800 feet out of a 7,800 foot roll. That amounts to a material loss 35.9% or $84 on a $234 roll of BOPP.
In comparison the Servo 3000 addition to a standard flexo press will bring the press into register in one press length, or 200 feet in this example. First let us assume the same number of press starts, 7. The material waste will be 7 starts x 200 feet = 1,400 feet. This is 18% or $42 a roll of BOPP. Now let's consider that the servo infeed on the Servo 3000 very precisely follows the press with 0.0025" resolution at full press speed. This typically means fewer or no reasons to stop the press. That being the case we remove two press stops for adjustments from the equation and we have 1 + 2 + 2 = 5 press stops resulting in 200 feet of waste per stop. This comes out to 1000 feet of waste or 12.82% of the roll at a cost of $30.
This is the difference between using a standard press to run this job and using a Servo 3000 assisted press. Using the Servo 3000 reduces the waste of substrate per stop and reduces the number of times the operator needs to stop the press. In this example we see a savings of $84 - $30 = $54 on a $234 roll of BOPP substrate, just under a quarter of the cost of the roll.
Check Out the Rotary Technologies Savings Calculator
This example only looks at savings on substrate. Every time a press is stopped it is not making money despite the fact that overhead continues. To really see what adding a Servo 3000 will save, the printer needs to go to the Rotary Technologies web site and use the savings calculator. That will show the savings on both substrate and overhead with the use of the Servo 3000 Digital Infeed + Re-register system.
(About the Author: Jim Walker is a technical writer working for Rotary Technologies)
