It is interesting to reflect that many of the techniques commonly in use in product printing and decoration today are simply derivations of techniques invented, in some cases, centuries ago. Developments in three dimensional product printing have largely been adaptations of printing techniques and technologies designed for paper. In reality no new printing process has been developed since the 1970's.
Flexapex is the trade name for a new printing process developed by Apex Machine Company to address some common problem areas existant in the commonly available printing applications used in the marking and decorating of three dimensional products.
Most high speed printing systems used in product printing utilize a process known as dry offset printing in which multiple ink colors are imprinted from a raised printing plate onto a central transfer (offset) cylinder with a rubber blanket. The offset cylinder then transfers all of the image colors to the printing surface substrate in a single impression. The inks used in dry offset are typically paste type inks, either in conventional air dry or in UV (ultraviolet) dry types. The inks are milled through a series of ink rollers before being applied to the raised printing plate by form rollers. Dry offset print machines can run at very high speeds and will produce high quality fine images and artworks. Printing of high quality large solid color areas or high density is not possible as, due to the milling of the inks through the inking system, the ink film that is transferred to the print substrate is typically very thin - approx 1 micron.
Where higher density ink laydowns are required for clarity of marking, for dense solid colors, or where light colors must be printed onto dark substrates, processes such as rotary gravure (pad print) or screen print (silkscreen) are commonly used. Each of these processes can provide good density of ink laydown - typically between 3 and 6 microns thickness - but each also have their disadvantages.
In the case of pad printing (gravure) the inks are solvent based to allow quick drying by evaporation of the solvents between the imprinting of each color - the main ingredient of these inks are Volatile Organic Compounds (VOCs), organic chemical compounds that have high vapor pressures . The chief advantage of solvent inks is that they are comparatively inexpensive, can be transferred in quite high densities and they enable printing on many different substrates. Disadvantages include the vapour produced by the solvent and the need to dispose of used solvent. Also, in this process each color must be printed separately, thus requiring re-registration between each color. The engraved printing plates/cylinders are expensive to produce and the process itself can be challenging due to the effect of temperature changes on the ink/solvent mixture percentages required.
In the case of screen printing each color must be printed and dried separately, either with solvent inks, as above, or with UV dried inks. The screens with the images to be printed are quite expensive to produce and generally have a short life expectancy. Screen print provides excellent density of ink laydown but production speeds are typically slow by nature of the process, thus giving high per piece production costs.
The Flexapex solution
FlexApex is an offset printing process developed by Apex Machine Company which utilizes modified flexographic inking technologies and UV (ultraviolet) cured inks in combination with the dry offset printing process in multi-colors and at high speeds. Unlike any other offset process, Flexapex provides the capability of transferring large volumes of ink for the printing of dense artworks and solids, thus offering great potential for improved quality of solids and for the printing of light colored inks onto dark substrates. Flexapex can also be combined with conventional dry offset printing in the same machine thus offering the best of both worlds. The process uses solvent free UV cured liquid inks and it is increasingly replacing solvent based ink technologies such as pad printing and gravure as well as providing a low cost alternative to silkscreen printing for high volume products. Flexapex provides a low-cost high speed technology which is easy to operate, and which provides great repeatability and very high quality.
The development of printing technologies
Below is a condensed history of printing showing some significant dates and developments which impact on and affect the printing of three dimensional products in today's markets.
Techniques commonly in use today, with approximate date of origination, include:
2000 BC - Metal Foil Stamping - used by ancient Egyptians who hammered gold sheets out into foils for decoration of tombs, etc. Now usually referred to as Hot Foil Stamping and used extensively for decoration of cosmetic items and the like.
AD 200 - Woodblock / Woodcut printing - originating in China in antiquity as a method of printing on textiles and later paper. Involved a raised print image, carved into a wood block, which would be coated with ink and then applied to the surface to be printed. Many printing processes today still use the principle of a raised print surface - the main differences being the method of production and the materials used for the raised image block/plate.
1430 - Intaglio (Gravure) - is a family of printmaking techniques in which the image is incised into a surface, known as the matrix or plate. Normally, copper or zinc plates are used as a surface, and the incisions are created by etching or engraving. To print an intaglio plate, ink is applied to the surface and then rubbed with tarlatan cloth to remove most of the excess. The final smooth wipe is often done with newspaper or old public phone book pages, leaving ink only in the incisions. A damp piece of paper is placed on top and the plate and paper are run through a printing press that, through pressure, transfers the ink from the recesses of the plate to the paper. This method of printing is still used today in Gravure and Pad Printing processes with improved and automated doctoring (wiping) of the excess ink.
1454 - Printing press - The mechanical systems involved were first assembled in Germany by the goldsmith Johannes Gutenberg around 1440, based on existing screw-presses used to press cloth, grapes etc., and possibly to print woodcuts, which were printed in Europe before Gutenberg. Although both woodblock printing and movable type printing press technologies were already developed first in China, and Korea several hundred years earlier, Gutenberg was the first in Western Europe to develop a printing press.
1796 - Lithography - is a method for printing using a stone (Lithographic Limestone) or a metal plate with a completely smooth surface. Lithography uses oil or fat and gum arabic to divide the smooth surface into hydrophilic regions which accept the ink, and hydrophobic regions which reject it and thus become the background.
1843 - Rotary press - rotary drum printing was invented by Richard March Hoe, and then slightly improved by William Bullock. Today, there are three main types of rotary presses - offset, rotogravure, and flexo (short for flexography). While the three types all use cylinders to print, they vary in their method.
1873 - Flexography - is a form of printing process which utilizes a flexible relief plate. It is basically an updated version of letterpress that can be used for printing on almost any type of substrate including plastic, metallic films, cellophane, and paper. Today it is widely used for printing on the non-porous substrates required for various types of food packaging and in the label industry. It is well suited for printing large areas of solid color as it can transfer far more ink to the substrate than is possible with many other processes, using special ink transfer mechanism know as an anilox roller. It works best on extremely regular flat surface substrates.
1886 - Hot metal typesetting - Two different approaches to mechanising typesetting were independently developed in the late 19th century. One produced characters on individual type bodies, known as the Monotype system; the other, Linotype, created slugs, usually comprising a whole line of text.
1903 - Offset press - Offset printing is a commonly used printing technique where the inked image is transferred (or "offset") from a plate to a rubber blanket, then to the printing surface. For printing onto porous surfaces like paper this is most often used in combination with the lithographic process, which is based on the repulsion of oil and water. The offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a water-based film (called "fountain solution"), keeping the non-printing areas ink-free. Ira Washington Rubel invented the first offset printing press in 1903.
For printing onto non-porous surfaces a technique known as "dry offset" - a process combining the characteristics of letterpress and offset is commonly used. A special plate prints directly onto the blanket of an offset press, and the blanket then offsets the image onto the substrate. The process is called dry offset because the plate is not dampened as it would be in the offset lithography process.
1907 - Screen-printing - its first appearance in a recognizable form was in China during the Song Dynasty (960–1279 AD). Japan and other Asian countries adopted this method of printing and advanced the craft using it in conjunction with block printing and paints. It was introduced to Western Europe from Asia sometime in the late 1700s, but did not gain large acceptance or use in Europe until silk mesh was more available for trade from the east and a profitable outlet for the medium discovered. It was first patented in England by Samuel Simon in 1907. Screen printing is still used in many applications for product decoration where vibrant colors and high ink density are requirements. Disadvantages include high set up costs, low speeds and difficulty of producing multi-color designs.
1960's - Pad printing - a printing process that can transfer a 2-D image onto a 3-D object. This is accomplished using an indirect offset (gravure) printing process that involves an image being transferred from the printing plate (cliché) via a silicone pad onto a substrate (surface to be printed). Most often seen in a reciprocating format although rotary pad-print machines are made for high volume applications. Utilizes inks with a high solvent* (VOC) content which rapidly evaporates to achieve the drying effect. Now considered ecologically unfriendly. Main advantages are the ability to print onto non-regular shaped surfaces and to transfer quite high densities of ink to produce well defined solid colors. Multi-color printing can be challenging due to the need for drying and re-registration between each color imprint.
1976 - Inkjet printer - used in many forms for basic product marking and coding.
1993 - Digital press (an advanced inkjet based technology) - mostly used in flat sheet paper printing, these have the ability to print streamed information direct from a computer in full color. Some limited applications of this technology are available for product printing and decoration, but the production speeds and unit cost prices for production still tend to rule out this type of process for many applications.
2005 - FlexApex - an offset printing process developed by Apex Machine Company which utilizes modified flexographic inking technologies and UV (ultraviolet) cured inks in combination with the dry offset process in multi-color and at high speeds. Unlike any other offset process, Flexapex provides the capability of transferring large volumes of ink for the printing of dense artworks and solids, thus offering great potential for improved quality. The process uses solvent free UV cured inks and it is increasingly replacing solvent based ink technologies such as pad printing and gravure as well as providing a low cost alternative to silkscreen printing for high volume products.