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Jun 1, 2007 12:00 AM
In roughly half of the plants I visit, I find presses packed incorrectly. Some of the most common excuses given are:
The list goes on and on.
Let's tackle an easy one first: I have yet to find the manual to be wrong on any press. Granted, some of the manuals on older presses are a bit hard to understand due to translation. If you do not have a manual for the press, then get one. Manuals are available from many sources.
Please keep in mind that a packing difference of 0.002 inch can adversely affect the print. Normally, you'll see mottle if the pressure is light. If the pressure is far too light, the result will be ink emulsification. In some cases, the emulsification will be severe. Mottle is not always a paper problem nor is emulsification always an ink problem; pressure loss can cause both issues.
Plate to blanket pressure is just as important to control on web presses as it is on sheetfed presses.
Ray Prince's “Tech Thoughts” run each month in New Products. Don't miss his podcasts at www.napl.org.
Raymond J. Prince is a leading expert in pressroom technical and operational issues. He recently joined NAPL (Paramus, NJ) as vice president and senior consultant, operations management. During his tenure at PIA/GATF, Prince conducted nearly 1,000 Technical Plant Assessments (TPAs), in-plant analyses of a printer's production facility and capabilities. As a lecturer and trainer, he led numerous industry seminars on all phases of pressroom operations. Contact him at (605) 941-1492 or e-mail RaymondJPrince@aol.com.