GC 444_Final GC 4440
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This 9 page Study Guide was uploaded by Allie S on Wednesday April 27, 2016. The Study Guide belongs to GC 4440 at Clemson University taught by Dr. O'Hara in Fall 2015. Since its upload, it has received 51 views. For similar materials see Current Trends and Deviations in Graphic Communications at Clemson University.
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Date Created: 04/27/16
Study Guide, 444/644 Final Exam The exam is primarily short answer, with some T/F and Multiple Choice. Some answers only require a word to answer, but most a couple of sentences. It is a long test; you need to move through it quickly. Answer the questions you know first, come back to the ones you’re not sure of. Take the time to read the question. If the directions say “Name and explain”, do both. Standards Differentiate between proprietary standards, defacto standards, specifications and formal standards o Proprietary: Tools and procedures developed by individual companies. Owned by the developer and all decisions lie with them. o Defacto: developed by individual companies, but have been adopted so widely that they become mandatory. Software applications like Adobe Suite, microsoft office References like pantone matching system Postscript Color sync PDF o Specifications: recommended practices developed by various industry segments. SWOP, FIRST, GRACoL, SNAP, etc.. Developed by committees o Formal Standards: Tools, procedures, and practices developed for the industry as a whole. IT8.7/1-4, ECI2002 CGATS 4, Densitometry, CGATS 5, Spectrophotometry ISO PDF-x, Ghent Workshop Developed by committee, formal development and adoption procedures. Formal standards include: Definitions Normative references Procedures annexes What are SNAP, GRACoL, SWOP, FIRST? o SWOP: specifications for web offset publications o FIRST: o GRACoL: General Requirements for Applications in Commercial Offset Lithography o SNAP: Specifications for the non heat set advertising production Discuss specifications as benchmarks o Specifications are an excellent benchmark o Can evaluate your process Not always required to meet specifications, just STANDARDS Standards are essentially rules Specifications are recommendations What are referenced printing conditions o Running the press to a pre-defined standard or specification Set standards - MUST meet o Many industry specifications are set up this way SWOP SNAP o Driven by advertisers to minimize variation between printers o SWOP, SNAP, previous GRACoL ran to standard densities Set densities for various paper grades Measure dot gain, build gray balance curves once the end point (SID) is met (gray balance is different for each press) Still a lot of variation, requires individual press characteristics Discuss how GRACoL 7 differs from traditional referenced printing conditions o To calibrate the press to a referenced printing condition Standardization aimpoints: Standardize paper color Standardize ink colors and 2/c overprints Standardize a neutral print density curve o G7 is a calibration Goal is to make all presses print the same Each press is calibrated to the G7 standard “appearance” Gray balance: 50 C 40 M 40 Y Uses colormetric data and density DIFFERS from the other who use dot gain curves to calibrate the presses Emphasis on MIDtones, not ENDpoints G7 Explain why a neutral print density curve is a more consistent reference point for the appearance of the print than a target dot gain. Explain how standardized paper color and ink color improves consistency across print platforms Explain why some printing processes focus on hue angle rather than the G7 LAB specs for CMYRGB solids when adopting the near-neutral density curve strategy Gravure Identify publication/packaging/product markets Discuss production considerations for each market Describe cylinder construction, quality checks Describe reclaiming cylinders o Dechrome the Cylinder o Cut away image layer with lathe Can cut away a few layers without re-electroplating o Degreasing o Polish, re-image and chrome Differentiate between engraving/etching methods, direct/indirect laser o Direct Transfer Create halftone dots Cell depth is the same, but the cells change sizes Photosensitive material applied directly to cylinder The film wrapped around the cylinder is exposed Unexposed material washes away to bare copper underneath Pros Increased productivity Gives higher resolution images o Indirect Laser Coat cylinder in resist Pros: Highest Resolution imaging system Use Laser to ablate cells Can create cells of varying shapes Can image line work with very little “jagged” edge Chemically etch, uniform depth o Engraving Chemical etching Electromechanical Engraving Primary/Dominant method of engraving cylinders Direct to cylinder, digital input Depth and size are variable, but fixed ratio As cylinder turns, diamond cutting tool enters the cylinder and removes copper to create cell Tool moves back and forth on the rotating cylinder The depth of cutting tool AND speed of cylinder determines cell sizes Can get 30, 45, 60 degree cells Spin faster and get elongated cells Distance between cells is always fixed To avoid moire K = 45 - 215 CPI C = 30 - 165 CPI M = 60 - 160 CPI Y= 30 - 120 CPI Engraving head can produce 6,000 - 7,000 cells/second Array of up to 14 engraving heads to produce 84,000 cells/second o Laser Engraving Uses Zinc engraving medium Can engrave up to 70,000 cells/second Two lasers on a single mounting for up to 140,000 cells/sec Not widely adopted Electromechanical is most popular Pros: Improved Ink release Less ink consumption Greater Resolution Greater repeatability Greater Contone Describe cell shapes, cell configurations, screening, moiré and ink transfer Discuss imaging issues, ink/print issues, ink transfer, ESA, registration (tilt and fit). Gravure in competition with other processes Doctor blade profiles, blade materials, doctor blade settings the “fit” and “tilt” of web registration. Expanded/Alternative Gamut Expanded Gamut vs. Modified Process o Expanded Gamut Definition… Involves adding additional colors like Orange, Green, and Violet in order to expand the range of colors a printer is able to print Combines CMYK with OGV o Modified Process N-color supplements or substitutes process colors with SPOT COLORS Reducing colors adds flexibility Change out the CMYK for Spot/Brand colors as needed Reduces print stations Production issues for each o Expanded Gamut Issues Screening Issues: 7 colors are more likely to Moire Need to find best angles for each color Orange/Cyan can’t mix -- put on SAME screen angle Green/Magenta can’t -- put on SAME screen angle Violet Moires at 0, sometimes put at 45 M/G - 75 Y - 0 O/C - 15 V/K - 45 Slight variations cause COLOR shifts Viscosity Density impression Registration Issues Slight shift causes color shifts Because colors are “double uped” any shift will change the whole color ECG Requires TIGHT registration HAVE to Design for 7 colors Gradients, drop shadows -- create depth Enhance chroma Avoid Vignettes and traps between spot colors o Modified Process Spot Color Inventory is high Need to have specific spot colors stored at all times Takes up space Spot Colors are less stable in their color composition Follow a formula, but not always exact Reducing colors adds flexibility Production advantages of ECG (makeready, inventory, ganging jobs, etc) o Expanded Color Gamut More productive Reduce Makeready One set-up for multiple jobs, longer runs Saves on Materials Only 7 inks - less to store One set of plates*** Able to gang jobs Multiple jobs on one because all use same colors Able to hit more colors and be more consistent Color Stability Press variation effects color’s stability less Because the adjacent color components are closer in hue angle Hue closer = less variation Easy to standardize Same anilox Same inks Same set ups o Modified Process Reducing colors adds flexibility There is little variation on brand colors Because you substitute brand spot colors for CMYK Reduce number of print stations Up to 10 colors Statistical Process Control Differentiate between process control and process capability, in control vs. in spec o Process Control o Process Capability Collect data Create Histogram Plot of frequency dist. approximates the output dist. of a process Evaluate Shape Want bell shape, but can be neg (right) or pos (left) skew Calc Mean and Std. Deviation Compare the process to the specifications Determine the % of in-spec and out-of-spec o In Control Natural variation of the process If the sampled averages fall within the natural process, they are IN CONTROL o In Spec Are we meeting all the limitations imposed on us? histogram/standard deviation tell you whether you are IN SPEC or not Histograms and run charts—what they are and how to evaluate them (is a process in control or in spec) Printed Electronics. Describe major types of functional devices (market areas) suitable to printed electronics Explain why ink uniformity, ink film thickness, edge acuity, and surface smoothness are critical to printed electronics performance Describe the sintering process; how it differs from simply curing the ink, and the differences for flake, micro and nanosilver inks What is meant by “the internet of things” Presentations at Research Forum Study the abstracts and your notes from student presentations. There will be several questions from your presentations
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