Technology Behind the Digital Magic A Crash Course on Industrial Printing John Sweeterman General Manager Digital Division INX International Ink Co
Deliver a Unique Experience for Everyone
Why make the change to digital? Consumers are demanding a unique experience with the products they buy. Brands are delivering something specific to the demographics they serve. Digital printing is transforming the ability to respond rapidly to changing design and brand strategy. A demand for specialized capabilities featuring short to mid run jobs with consecutive numbering, bar coding, as well as variable data is quickly on the rise.
Traditional vs. Digital Printing
Traditional (Analog) Printing A traditional printing system is referred to as Analog printing Uses a plate, cylinder, or screen as a template from which a large volume of prints are made
Digital (Non impact) Printing The use of inkjet or electrophotography (laser) printers to decorate substrates (material in which you are printing on) directly from digital data With inkjet printing, computer controlled electronic impulses are created that result in the generation of droplets that are directed in rapid succession onto the substrate to form the image
The Workflow Image/File Digital Image/File Manipulation Traditional Raster Image Processor (RIP) Films Inkjet Printer Drying Finishing Final Print Collation & Storage Customer Screens Make Ready Screenprinting Drying Finishing Final Print Collation & Storage Clean-up Customer
Pre Press Proofs are typically required by customers prior to the start of production in order to see what their final product will look like With digital printing, the same equipment can be used to print proofs as well as run the final job Provides confidence at no additional cost
Understanding Inkjet Printheads
Continuous Inkjet (CIJ) Continuous Inkjet (CIJ) Drop on demand (DOD) or impulse inkjet
Continuous Inkjet (CIJ) Continuous flow of ink from a pressurized reservoir Acoustic or ultrasonic pressure waves break the stream of ink into individual droplets The droplets are then charged by passing through an electric field The strength of the charge on the drop determines how far the droplet deflects and where it lands on the substrate The deflected droplets build up the image and the noncharged droplets are collected and recirculated
Continuous Inkjet (CIJ) Advantages High velocity (50 m/s) of the droplets Allows for long distance between print head and substrate Nozzles do not clog as often since it is continuously wetted with ink Allows for the use of solvents that can go into nonporous substrates leading to good adhesion and fast drying Speed is advantageous Capable of running at speeds of over 1,000 feet per minute Application: Commercial
Drop on Demand Inkjet (DOD) A drop of ink is only generated when a drop is needed The print head (consisting ink nozzles) releases the ink in droplets that are created in response to specific electronic impulses corresponding to the image being printed No excessive droplets released that need to be deflected Simpler system since no electrostatic charge needs to be generated No deflection/recovery needed With this system, the stationary print head is about 1/8 or less from the substrate
Drop On Demand Technologies Piezoelectric Inkjet Utilize a ceramic material that performs the reverse piezoelectric effect It deforms when a voltage is applied
Piezo DOD Type of technology used by most commercial and industrial inkjet printers Can use wider variety of inks than thermal or continuous Molten ink ejected onto substrate and solidifies as it cools on the surface of the substrate Application: Packaging, Commercial & Large Format Signage
How it works: Piezo DOD
Binary vs. Grayscale Printing
So what s the difference? Binary The first printheads utilized this technology They either printed a drop or they didn t Grayscale Newer printhead technologies utilize this Feature variable drop sizes Yields results that are perceived as higher quality
Grayscale Printing Fire drops made of smaller sub drops Typically between 3 6 picolitres Varying the drop size tricks the human eye to see a smoother image gives a higher apparent resolution Printing with multiple drop sizes means you can get a higher productivity along with higher quality out of a small number of nozzles
Binary and Grayscale Comparison
Comparison of Ink Jet Methods Piezo (DOD) Continuous Drop Speed Higher Highest Resolution High Low Inks Water, solvent, oil, UV, Hot melt Water, Solvent, UV Head Cost Higher (throw away) Highest Substrates Paper & Nonporous substrates Paper & Nonporous substrates
Scanning vs. Single Pass
Scanning Term used in inkjet industry for multi pass printing Means that the printer performs many passes over the substrate The printhead scans back and forth Ensures full coverage of the image Allows printing dots on a finer grid Downfalls: Relatively slow due to multiple passes Time is lost at each end of the scan for turnaround Can degrade small print features like small text and fine lines
Single Pass Printheads are fixed in one place and print directly on the moving substrate Printheads aligned and assembled into a print bar to mount into the machine Primary benefit: Higher speed = increased productivity
Printer Resolution and Print Quality
Printer Resolution DPI Dots Per Inch Ameasure of the native resolution of the printhead Example: 360 DPI printhead Has nozzels that are 1/360 th of an inch apart Ability to print a dot on a grid spaced at approximately 70 microns 1/360 = 0.0028 = 70 microns
DPI Further Explained
Inkjet Inks
Inkjet Inks Basics Can be liquid, solid, or dry powders Made of: Colorant (dyes or pigments) Binder Additives Liquid inks can be: Solvent based Water based Oil based UV curable Other components: Surfactants control surface tension of ink droplet formation Binders improve elasticity of ink Dispersants aid the dispersion of colorant in carrier fluid
Requirements for Inkjet Inks Inks cannot dry in nozzles Must maintain fluid state (including shut down) Inks must dry within time frame required by specific application & printer Ink should have resistant properties required for end use application Ink should provide acceptable print quality on wide range of substrates
Other considerations for Inkjet Inks Primers A primer is sometimes used for some materials which allow inks to set up on the primed material. An OPV can also offer a gloss or matte effect Performance There are may Ink types which have varying resistant properties to fade, rub, gloss.
UV vs. WB Inks Drying UV inks are energy curable inks and water based inks are dried by heat/air. Performance If using pigment inks, UV & WB inks have about the same fade resistance. UV inks are generally considered more durable to rub resistance.
Ink Delivery Systems for Inkjet
Functions of the Delivery System Filter the ink Minimizes chance of particles clogging the nozzles De gas the ink Removes air bubbles Heat the ink Insures it is the proper operating temperature Continuously circulate the ink through the printhead
The Market for Inkjet Packaging represents a very large and stable opportunity for the digital printing market Digital technology is becoming more affordable with faster speeds, and higher resolution. Most Importantly.. Our consumers are unique..and you can now deliver a unique experience though the types of packaging you offer.
Primary Packaging
Tag and Label Markets Packaging Point of purchase displays
Display & Packaging Unlimited Possibilities
A unique fingerprint for every product
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