Abstract

The purpose of this study was to determine if the Epic Delta dampening system removed and eliminated 98% of the plate-caused hickeys that occurred on press runs with a continuous plate-feed dampening system. This was accomplished by comparing the proportion of hickeys per 10,000 cartons that occurred with a continuous plate-feed dampening system, to the proportion of hickeys per 10,000 cartons that occurred with the Epic Delta dampening system. The data were obtained from carton quality audits of jobs run on a press with a continuous plate-feed dampener and carton quality audits of the same jobs run on the same press with a Delta dampener. A 55" six-color sheet-fed press with a coater/perfector was used. Each week jobs were randomly selected by the quality control auditor to be audited and visually inspected for defects such as poor register, picking and hickeys. The number of serious and major hickeys that occurred and the number of cartons inspected each week, were recorded from these audits over a twelve week period for both dampening systems. The printing jobs were grouped according to ink coverage and ink sequence into categories A, B, C, and D. The chi-square test of homogeneity was used to test if the Delta dampening system significantly reduced the proportion of hickeys that occurred with the continuous plate-feed dampening system. No hickeys were recorded for cartons in categories B and D so the data recorded in categories B and D were not analyzed. The calculated chi-square value for cartons in category A was 25.30. The chi-square table value for five degrees of freedom at the alpha level of .05 was 11 .07. The null hypothesis was rejected for category A. The Delta dampening system did significantly reduce the proportion of hickeys that had occurred on press runs with the continuous plate-feed dampening system. The data recorded for cartons in category C could not be analyzed using the chi-square test of homogeneity because no hickeys were recorded for the cartons run on the press with the Delta dampener. The t' test was used to determine whether there was a significant difference between the average proportion of hickeys per 10,000 cartons that occurred on press runs with the continuous plate-feed dampening system, and the average proportion of hickeys per 10,000 cartons that occurred on press runs with the Delta dampening system. The null hypothesis was rejected because the absolute value of the calculated f value of -1.94 was greater than the table value of 1.812. In category C the Delta dampening system did significantly reduce the proportion of hickeys that had occurred on press runs with the continuous plate-feed dampening system. The data from categories A and C were combined to calculate the average proportion of hickeys per 10,000 cartons that occurred on press runs with the two dampening systems,

Library of Congress Subject Headings

Offset printing--Quality control; Printing--Quality control.; Lithography--Quality control

Publication Date

2-1-1995

Document Type

Thesis

Department, Program, or Center

School of Print Media (CIAS)

Advisor

Frazier, Cliff

Advisor/Committee Member

Layne, Charles

Comments

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: Z252.5.O5F644 1995

Campus

RIT – Main Campus

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