A study to examine tone reproduction affected by squgeegee hardness in the screen printing process.

• Main Authors: John, Shy, 施位翰
• Other Authors: S. T. Lee
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/65627494790690510532

碩士 === 文化大學 === 造紙印刷研究所 === 83 === Screen Squeegee is a simple but quite important printing tool. Young M. (1988) indicate there are 8 variances at least could affect or control tone reproduction, hardness is one of those. For line art, It''s not apparent that ink deposit influence on solid ink density. But for halftone dot, Total tine density affects by IFT(ink film thickness) and DDP (dot area percentage) , so that It varies more than line art. For keeping density constanting, to approach quality control goal. This research studies how screen Squeegee Hardness influence on screen printing tone reproduction qualities, tone items including TTD (total tine density), tone reproduction curve, DG( dot gain) and PC(print contrast).Dependent variable is Squeegee Hardness, indepedent variable is TTD of 11 tone grades of gray scale on print layout printed by screen press. We draw 31 sheets randomly from qualtied printed sheets preselected with SPC(statistical process contral) to provide for raw data measurement. 1 Squeegee hardness has significant influence on TTD, DG and PC. 2 Squeegee hardness is negative relation with TTD and DG, but is positive relation with PC. 3 Under different Squeegee Hardness, plate-press curve show S-shape. It exists quite difference from U-shape of ideal plate-press curves. Research finds that hardness above 67.43o, curves vary regularly, under 67.43o change irregularly. Squeegee Hardness between 67.43o and 82.7o, plate-press curves downward with hardness increase, but It shows a constant tendency. 4 Squeegee Hardness between 67.43o and 82.7o, It''s TTD, DG and PC are is variating constantly. It is suitable for Screen Printing . Although hardness 93. 27o is best for tone quality but not for other Printing requirement. 5 Finding that inter-active among Squeegee 8 variances, DG Maximum point moves from 50% dot area to 60% area with hardness increase and then fixes at 60% dot area. 6 Best regression model is : y=b0+b1x1+b2x2+b3x3+b4x4