- May 01, 2009, By David Argent Contributing Editor
A standardized process can be defined as one that represents a single way of doing an activity in which all employees do the activity the same way all of the time, across multiple production lines. Exceptions to the standard way of doing things cause loss of efficiency, increased waste, and lower quality of output.
Exceptional improvements have been made to each printing process. The traditional crafts dependent on lots of tinkering are now technology-driven systems. There are still areas of opportunity for more standardization. An example in flexo printing would be the need for anilox standardization in some pressrooms.
Proliferation of anilox rolls means ink must be blended for many individual processes, often overwhelming the ink department's ability to function effectively. This becomes more complex when several presses are involved. In this case, I have found an audit of the inkroom will surface several repeating problems:
- Color standards are not linked to specific press metering — there simply are too many different anilox rollers.
- As shown in the table, ink density is a direct function of anilox volume.
- There is no reliable proofer correlation to the press. Ink toning at the press becomes the norm.
- Press returns do not match when used for repeat jobs, even on the same press, and therefore require toning.
- Jobs are not portable from press to press and location to location.
- Ink estimation is off, and too much or too little is made for the press run.
Most flexo pressrooms collect data that, if examined, will highlight these problems and point to the root cause, so a program to rationalize anilox rollers could be tracked with numeric goals. To make improvements, there would be three stakeholders working closely in the project, namely the anilox supplier, ink supplier, and the converter. The overall outcome would have three basic anilox criteria:
- The same volumes (bcm) for each line screen (l/s) within the inventory. For example, all 360 l/s would be 5 bcm and all 800 l/s would be 2.0 bcm.
- The same volume and line screen on all rolls for each press.
- Use of roll tags to identify line screen and bcm volume of each anilox roll.
Starting with one press, a stepwise procedure1 for arriving at the fewest standard anilox rolls would involve review of current anilox inventory and product mix. A banded roll test would be run to optimize and standardize process aniloxes. Many times, the number of anilox roll specifications can be cut in half. The findings from the first press would then be applied to the other presses in the pressroom and to other locations producing the same kind of work.
At this point, it is possible to correlate lab proofing to the press, and the chart shows some very impressive data2 for a bladed, easy-to-use flexo hand proofer. Very close correlation was achieved to the press over a broad range of colors, which can ensure that the ink delivered to the press is correct for shade and strength.
Having established the fewest anilox rollers with optimum volumes and screen counts, inspection and maintenance are essential. This ensures the rolls have not lost significant volume due to wear or plugging. This advice applies to both press and proofer anilox rollers.
The combination of anilox roll rationalization combined with proofer correlation sounds like a mandatory but simple program. What would you find in your operation?
1David Watson, Harper Corp., FFTA Forum 2004.
2Bill Paulson, Harper Corp.; Kurt Knudson, Water Ink Technologies, FFTA Forum 2008.
Process improvement expert David Argent has 30+ years of experience in process analysis with particular emphasis on ink and coating design and performance. Contact him at 314-409-4304; firstname.lastname@example.org.
|PMS Color||Press Sample Density||Lab Proofer Sample Density||Press Anilox Volume (bcm)||Lab Proofer Anilox Volume (bcm)|