GC 440 - Week 8 Notes
GC 440 - Week 8 Notes GC440
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This 5 page Class Notes was uploaded by Allie S on Friday October 16, 2015. The Class Notes belongs to GC440 at Clemson University taught by Dr. Weisenmiller in Summer 2015. Since its upload, it has received 34 views. For similar materials see Commercial Printing in Graphic Communications at Clemson University.
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Date Created: 10/16/15
Offset Vs Digital Digital 0 Is best suited for runs of less than 1000 0 Lower initial costs best for short runs 0 Leverages the power of Variable Data VDP Offset Litho 0 Has a higher setup cost which is why you should do longer runs 0 High productivity 0 Price per piece diminishes with quantity Digital NOW produces about 15 of COMMERCIAL PRINT but is projected to grow to 20 0 most continue to see print as a valuable medium that allows them to push content to consumers vs relying on consumers to seek out the marketing content via electronic communicationquot Offset Litho Dominated the 20th century 0 Compared to Flexography 0 Costs more higher setup press costs 0 More complex longer more involved setup 0 Not as versatile in range of substrates 0 Uses a planographic image carrier Flexo is a simple process 0 Flexo uses a relief plate Press Tech Trends 0 Integrated computer workflow 0 Hybrid capabilities o Mixing processes digital flexo rotary screen etc 0 Increased inking capability 0 Auto ink dispensing and ink zoning 0 Larger form rollers Prevent ghosting and roller starvation Anilox fountain roller engraved Improved automation and controls 0 Cleaning loading temperature controls 0 Closedloop color control 0 UV technology These are process and quality control parameters to be controlled in the pressroom Define these terms determine what instrument should be used to measure them and assign tolerances to each factor Print QUALITY 1 Register 0 2 Fit 0 3 Backup 0 4 Density 0 Dot gain 0 Color 0 Print Contrast Gloss Consistent Lay of solids Ink Trap 0 Dot Structure 0 Slur Ink gloss Doubling Hickeys Scratches Coating smoothness clarity gloss 3 North American Printing Conditions GRACOL 1 SWOP 3 SWOP 5 GRACoL General Requirements for Applications in Commercial Offset Litho SWOP Specifications for Web Offset Publications 0 Printing falls into distinct categories 0 GRACoL for commercial offset 0 SWOP for publication printing lower quality IDEALLIANCE has provided the industry with these data sets Process Control 7 things to check when running a press 1 Is it straight to the lead edge of the press sheet 2 Is it printing in the same place lead to tail 3 Is it printing in the same place left to right 4 Is it printing in the right place lead to tail 5 Is it printing in the right place left to right 6 Is the impression set correctly 7 Are the ink and water balanced Difference between REGISTER and FIT Register is the positioning of the sheet relative to the image on the blanket o Helps to determine SAME PLACE Determined by cylinder marks on edge of sheet This is step 2 and 3 on list 0 Fit describes the juxtaposition of all image elements in the printing area without regard to the sheet margin determined and maintained as a result of registering the plate and sheet 0 colors lining up with each other in the right place on the sheet Determined by steps 4 and 5 on list REGISTER Register is the overall agreement in the position and alignment of printing details on a press sheetquot 0 Also The proper positioning of the sheet with respect to the image on the blanketquot 0 Once square the plate image can be moved by the operator on the flyquot both circumfrencially amp laterally using running register controlsquot Advantages of cylinder marks Before during and after ensures consistency After first cut first cut register corner guide corner the cylinder marks should be located in the back left corner Side to side Ensures that you re printing in the right place and same place You must know the press sheet size in order to place the cylinder marks accurately Three ways to add cylinder marks imposition software or page layout software manually mask a scribed piece of film Scratching the plate 2 problems with this could hurt the blanket a burr can slit the blanket or rollers BACK UP 0 When you are printing the back side make sure the images line up to each other fronttoback 0 Straight to lead edge is not necessarily as important as straight to each other when you are examining this aspect 0 Use a light table to check How do you assure the job will print straight and centeredquot when running through the press 0 Digital Stripping Imposition 0 Consider o Press format 0 Sheet format 0 NUp o Impo method 0 Mount plates 0 Cut paper 0 Feed press resister 0 Guide corner 0 Cylinder marks Causes of a Job Not Printing Square I Stripping an operator sensitive condition Digital Template II Plating punched crooked flats slipped off of the pins III Mounting another operator sensitive condition IV Cutting and Feeding paper paper not jogged well head stops angled feed and registration table not set up properly Standard Operating Procedures SOP s 0 Side guide 0 Centers sheet Headstops 0 Square sheet 0 Drive WheelsBelts o Align sheet stream 0 Tail Drive Wheels 0 BoxIn Sheetquot 0 DoubleSheet Detector DoubleSheet Detector Prevent waste machine damage 0 Three types 1 Mechanical 0 Operator must calibrate a physical sheet gap tolerance 2 Optical Senses opacity of sheet used on DI 3 Ultrasonic The sensor operates by beaming ultrasonic sound waves through the material from one side and measuring the intensity of the sound detected on the other side Press Vs Duplicator Text book reason Format Size 0 Others that are more specific a Accuracy of the controls b of rollers c Feed pile i Air blast at tail of sheet ii Stream feeding iii Registration accuracy d Complexity of the dampening system e Speed f Perfecting Both Sides Accuracy of controls 0 Pull guides 0 Side guidequot Impression 0 Head stops 0 More control over angling and moving plates
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