Weyerhaeuser’s Flexo Printing Facilities Streamline Plate Mounting
November 2007
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Challenged with shorter lead times, smaller order quantity, and tighter registration, forest products giant, Weyerhaeuser, increased prepress production by 100 percent, cut downtime between runs, reduced prepress waste, and improved safety with new digital Vision Plate Mounter/Proofer system from Leader Engineering
by Jim McMahon
Flexographic printing had long been considered a low-quality printing system, but a mainstay for the printing of packaging containers, such as corrugated boxes and flexible packaging like food bags, shopping bags, and self-adhesive labels. Technical developments over the past few decades in the flexo printing process have improved print quality, such as by enhancing the ability to reproduce highlight tonal values, working around the very high dot gain associated with flexo printing, and by making accessible 4+ color applications. But, the systems for the mounting and calibration of flexographic plates onto printing cylinders had not evolved technologically, that is, substantially enough to provide for quick and highly accurate mounting of the flexible printing plates.
Plate mounting bottleneck
The quality of a flexo printing job depends, to a large degree, on the care in which prepress preparations are carried out. This includes mounting the flexible plate on the printing cylinder, checking color registration, and proofing. The mounting of the printing plates onto printing cylinders requires a high degree of alignment accuracy. The image on the printing plate must be perfectly square and in register with the printing cylinder in order to print clearly. The arrangement of the printing plates in the exact predetermined relationship with one another requires that their position be accurately determined prior to mounting.
After the plates are mounted onto the cylinders, the printing press operator must stop the press to examine the print results for acceptability. If out of registration, many times, the operator must remove the plates from the cylinders and start over from the beginning. This activity is very time consuming resulting in substantial press downtime.
A common method to mount and align the printing plates on the printing cylinder involves the drawing of a line around the printing cylinder. This line is then aligned by eye with a longitudinal line along the length of the photopolymer or other printing plate. The plate is then wrapped around the cylinder. This method is somewhat accurate but can be extremely time consuming for the operator, leading to delays between print runs.
Other plate mounting and calibration systems have been devised for flexo printing using manual or semi-manual systems, such as employing rods for rolling the plate onto the cylinder, light projection to position the plates, plate vacuum suction devices, and registration pins and holes to align the plates on the cylinder. Each of these methods have proved error prone in registration.
by Jim McMahon
Flexographic printing had long been considered a low-quality printing system, but a mainstay for the printing of packaging containers, such as corrugated boxes and flexible packaging like food bags, shopping bags, and self-adhesive labels. Technical developments over the past few decades in the flexo printing process have improved print quality, such as by enhancing the ability to reproduce highlight tonal values, working around the very high dot gain associated with flexo printing, and by making accessible 4+ color applications. But, the systems for the mounting and calibration of flexographic plates onto printing cylinders had not evolved technologically, that is, substantially enough to provide for quick and highly accurate mounting of the flexible printing plates.
Plate mounting bottleneck
The quality of a flexo printing job depends, to a large degree, on the care in which prepress preparations are carried out. This includes mounting the flexible plate on the printing cylinder, checking color registration, and proofing. The mounting of the printing plates onto printing cylinders requires a high degree of alignment accuracy. The image on the printing plate must be perfectly square and in register with the printing cylinder in order to print clearly. The arrangement of the printing plates in the exact predetermined relationship with one another requires that their position be accurately determined prior to mounting.
After the plates are mounted onto the cylinders, the printing press operator must stop the press to examine the print results for acceptability. If out of registration, many times, the operator must remove the plates from the cylinders and start over from the beginning. This activity is very time consuming resulting in substantial press downtime.
A common method to mount and align the printing plates on the printing cylinder involves the drawing of a line around the printing cylinder. This line is then aligned by eye with a longitudinal line along the length of the photopolymer or other printing plate. The plate is then wrapped around the cylinder. This method is somewhat accurate but can be extremely time consuming for the operator, leading to delays between print runs.
Other plate mounting and calibration systems have been devised for flexo printing using manual or semi-manual systems, such as employing rods for rolling the plate onto the cylinder, light projection to position the plates, plate vacuum suction devices, and registration pins and holes to align the plates on the cylinder. Each of these methods have proved error prone in registration.
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