Metal embossing dies from DMS
By Jack Kenny
To understand how a label works, it is necessary to possess a reasonably functional pair of eyes. In the supermarket, wine shop or pharmacy, you browse the labels with your eyes. A package will appeal to you because (a) you saw on the label what it contains, and (b) you are pleased by the graphics. If that label possesses a third dimension, you will see that also, and then you will reach out your hand and touch it. For some products, that clever graphic element will make the sale.
The third dimension on a label is produced by embossing. The process is quite common in other products: We see and touch embossed paper napkins just about every day, for instance. But brand owners know that raised images, textures or type on a label – combined with design, color, and other key elements – elevate the product in the mind of the consumer. The addition of detail and depth make the product stand out visually, and the tactile effect makes the consumer want to reach out and touch.
“Embossing offers a label effect that provides depth and richness to the design which in turn provides inherent value to the product,” says Andy Schmitz of RotoMetrics, a manufacturer of rotary tooling, including embossing dies. “In addition, embossing provides tremendous pick-up value because of its unique effects which translate into both visual and tactile features.”
Like cutting dies, traditional embossing dies are made of steel (and sometimes brass) except for those made by Trinity Graphic USA, which are photopolymer. All embossing dies come in pairs: a male and a female, which are mounted into a standard die station.
“The basic theory of embossing is simple,” says Schmitz. “The key elements are precision, timing and pressure. Embossing tools are precision engraved using extremely tight tolerances. All embossing tools have a specific clearance relative to the thickness of the material so the clearance must be identified. Embossing usually requires a two-tool set that includes a female and male cylinder that work in unison and must be perfectly timed with one another. The top tool, known as the female, rides above the surface of the web; the male tool, or bottom tool, runs below. The two tools timed together create an impression in the substrate. We also have the ability to add embossed texture with a single tool. In this scenario, the embossed texture is engraved in the surface of a single tool. A special rubber coated anvil is used under the substrate to support the embossing/texturing process. We can create texture or replicate a texture from a sample or we offer a library of stock texture patterns to choose from.”
Magnetic embossing dies are available to narrow web converters as an alternative to solid tooling, which comes at a higher price. “Magnetic embossing die plates create similar embossing effects as the solid emboss tools, but they work differently,” Schmitz notes. “There are pros and cons to both traditional embossing solid tools and magnetic emboss die plates. Solid tools are manufactured at a specific repeat size, while magnetic die plates offer variable repeat sizes. Solid tools provide a deeper, complex 3D sculptured emboss effect, but are considerably more expensive then the single-level magnetic emboss die plates and take the longer to manufacture. The magnetic emboss die plates are also easier to store and less expensive to ship.”
The most common substrates for embossing are paper and paper-foil laminates. Though there are a few films that can be embossed, most film substrates have a shape memory, so the embossed image will disappear as the film returns to its original state of flatness.
Schmitz of RotoMetrics says a simple test will indicate if a substrate is suitable for embossing: “Simply hand-fold down a corner of the substrate you wish to emboss. If the substrate holds the fold at 180° to 90°, it’s suitable for embossing. If the substrate holds the fold at 90° or less, it is unsuitable.”
The visual appeal of an embossed label is the result of a rather minor elevation in the substrate surface. At arm’s length, the human eye cannot tell that one part of the label is five one-thousandths of an inch closer than the rest. The eye is registering the light that bounces off of the edges of the embossed area; what we see as a raised image is caused in large part by the reflectivity of the material rather than the height of the embossed area.
Then there is the tactile appeal. Running one’s fingers across an embossed image on a wine label or perfume label doesn’t make a genie pop out of the container, but it does transmit the ineffable sense that what’s in the bottle is special.
An embossing plate for use in Manroland’s new InlineImpress embossing unit. Instead of embossing the image into the substrate, the plate interacts with a coating to create the embossed effect on the surface of the material.
The wine market, of course, has had a love affair with embossing for many years. Other traditional markets are direct mail, usually in the form of stickers, and hang tags for clothing at retail. Cosmetic labels, as well as cartons, are making use of embossing to distinguish products in a highly competitive industry.
Most wine labels are paper, and they must deliver the winemaker’s message – be it elegance, fun or attitude – to the prospective customer. But papers are a challenge. From a microscopic perspective, paper will have the appearance of a mountainous landscape. Classic laid papers can pose a challenge to the printer because inks must be made to penetrate all the valleys. Embossing, however, can overcome this challenge. If the printer uses semi-gloss or even a matte finished paper, a texture can be introduced via embossing during postprint converting inline. The result would be a good looking label on a less expensive material.
Embossing has many uses in industrial applications. Some mobile phone parts are embossed; dimple patterns can make gripping easier; and emboss marks on tickets can make them more difficult to counterfeit.
New embossing technologies continue to evolve. RotoMetrics and the UEI Group Companies (manufactures of the rotary foil stamping and embossing product line sold exclusively by RotoMetrics) can now manufacture complex 3D sculptured embossing tools with added detailed texturing, engraved together in a one tool set, says Schmitz. “In the past, applying embossing and detailed texturing would have been done in two separate die stations, requiring two different die sets,” he observes. “Combining these two decorating processes together simplifies manufacturing, reduces cost and improves efficiency while providing sophistication and inherent value in the label.”
Embossing with photopolymer
Twenty-four years ago, Robert and Keith Smithson came up with the idea that they could use photopolymer letterpress plates to emboss images in papers and foils. They found this out by observing the images that over-impression of plates made in substrates. Their pioneer project was for Glenfiddich, the Scotch whisky. Since then photopolymer embossing has remained a strong part of Trinity Graphics’ business, both in the USA and in the UK.
“Because of this technology, embossing has grown dramatically,” says Robert Smithson, whose company sends embossing plates to converters in such places as South America, Russia and South Africa. “I’m sure that probably 50 percent of wine labels are embossed using photopolymer plates now.” Trinity Graphic USA sends out an averate of 20 sets of embossing plates each day, and some of the largest wine producers in the country are among its customers.
Unlike plates used in flexography, which are more flexible, letterpress plates have a harder durometer. Manufacturing them, however, is not as simple as just choosing a plate material, according to Smithson. “Two different light sources are required for exposure, to create the shoulders on the male and female plates,” he says. “A lot of it is understanding the different embossing qualities of the label materials. Some papers are better for embossing than others.”
When a thicker substrate is required, the plates have to be designed with more space between the male and female. Lately, Smithson notes, his production has moved beyond the label converters to carton producers who are embossing on 16- to 18-pt. board. These folded cartons, he adds, are mainly for products in the pharmaceutical and cosmetics industry.
“Another change is that a lot more people are switching to cold foil and embossing. That’s been growing,” says Smithson.
Photopolymer embossing plates are less expensive than metal embossing dies. Smithson says that the lifespan of a set of plates, while shorter than that of steel, is quite long. “We have had them running 24 hours a day, seven days a week for millions of impressions. Let’s say they start to deteriorate; a new set will be inexpensive to replace.”
Setup, operation and changeover of the photopolymer plates is simple, according to Smithson. The converter buys a pair of die blanks and puts double-sided mounting tape on each. At the end of a run the plate is demounted and a new set installed.
The male plate is mounted on one cylinder, which is then placed first into the die station. The female plate is then placed atop the male plate and the images matched. Then the cylinder for the female plate is set in place atop the male cylinder, and the plate secured to it. The web is then jogged between the embossing cylinders and placed into registration.
Smithson says that the process, from the printer’s perspective, is easy. “I probably have had to visit only 10 companies to demonstrate how to do this.” Trinity Graphic has produced an eight-page PDF demonstrating the process with pictures and words.
Speed, he adds, is not an issue: “We ran 1,000 feet per minute for one company 10 years ago.”
The only limitation that photopolymer embossing has is its inability to create 3D images – those with more than one depth of emboss. “We have achieved it, however, with two sets of embossing tools in two die stations.
Industry pursues Braille
In 2005, a law became effective in the European Union requiring newly approved medicinal products to include Braille in its carton packaging. All existing medicinal products had until October 2010 to comply. No such law exists in the USA or Canada, but industry forces have combined to establish a Braille standard for both countries. In 2009, the International Association of Diecutting and Diemaking (IADD), in cooperation with the Braille Authority of North America (BANA), established the IADD Can-Am Braille standard. BANA’s mission is to ensure literacy for tactile readers through standardization of Braille and/or tactile graphics with the purpose to promote and to facilitate the use, teaching, and production of Braille. This mission involves embossing.
The use of Braille has declined in the US. In 1960, half of legally blind, school-age children were able to read Braille. By 2007, that number had dropped to 10 percent of blind school kids who use Braille as their primary reading method.
A report by the Foil & Specialty Effects Association (FSEA) details the Braille standard, and goes into detail about the embossing technologies that are required to produce functional Braille on packaging. The report can be viewed at www.fsea.com/ifmagazine/article.asp?ID=111.
According to FSEA, the new standard includes details on the balancing of strong deep Braille embossing while avoiding breaks in the carton surface that can make the cartons aesthetically unacceptable. It also discusses material selection and the wide range of carton boards in the marketplace. The standard also points out that it is not possible to prevent minimal variation in embossing heights on the same folding carton or in the same production batch.
The fabrication section discusses the methods available for embossing the Braille and the recommendation of encompassing the embossing within the cutting tool or applying the Braille in-line in the folding/gluing process. It also outlines the correct positioning of the Braille embossing and the amount of text that can be incorporated on a specific carton.