Rotary embossing: embossing gives labels that extra measure of appeal. Today's converters have a choice between metal and photo polymer embossing dies.
"One of the main purposes of a label or package is to gain the customer's attention through visual appeal, brand recognition, competitive shelf advantage and pick-up value," says Nicole Mercer, marketing manager for Universal Engravers Inc. (UEI Group) of Overland Park, KS, whose embossing tools are marketed by RotoMetrics. "One of the primary goals is visual: Does it grab your attention, does it stand out from the rest? Embossing adds another dimension because it is both visual and tactile. The more detail and depth, the more it stands out visually, and the tactile effect provides pick-up value because customers want to touch and feel. By adding embossing to a label or a package, one gains a tremendous competitive advantage in the buying decision, because embossing gets the customer to actually pick up the package."
Like cutting dies, traditional embossing dies are made of steel, except for those made by Trinity Graphic USA, which are photopolymer. Embossing dies come in pairs: a male and a female, which are mounted into a standard die station. In a web fed press with the printed image face-up, the male die goes in first, on the bottom, and the female mounts on top. As the substrate passes through the nip, the image is embossed.
Paper and paper-foil laminates are the most common substrates for embossing. Films generally are difficult, because they have a shape memory, and the embossed image will disappear as the film returns to its original state of flatness.
"One of the fascinating things about embossing is that if you take an embossed label and hold it at arm's length, the human eye can't tell that one part of it is five-thousandths of an inch closer at that distance," says David Polkinghorne, president of DMS Inc., Lake Zurich, IL. "What you actually see is light that bounces off the edges. As you move the label, it glimmers a little bit. Embossing is really about the reflectivity of the material that determines how it looks, rather than the height of the emboss."
There's not much in a standard emboss to create a shadow, Polkinghorne says. "It's about the bent corners refracting light at all different angles. If you're looking at it from a 45[degrees] angle, and the light is coming in at 45[degrees] from the opposite direction, the light catches the corners so that as you move, the highlights move. If you look at it without moving it you won't see much, but when you move the object you see the light hit those bent edges.
"The other effect is tactile," he adds. "You can feel the difference. We made dies for one customer that had a flagstone emboss, which was used on a matte material. You can't see it at all but when you touch it it feels interesting." Height difference between the base substrate and the embossed area, he says, is typically 10 thousandths of an inch. "It depends on the job you're doing. For wine labels, it's generally not very deep."
Rotary embossing is getting a lot of attention in the wine labeling business. Other markets have traditionally included direct mail, usually in the form of stickers, and hang tags for clothing at retail.
Papers used for wine labels must deliver the proper message of elegance to the customer, and quite often the estate papers, the classic laid papers, make printing difficult. Embossing can come to the rescue, with a raised texture.
"Classic laid paper is horrible to print on," says Polkinghorne. "You have to squeeze out to get into the peaks and valleys. But if you can print on semi-gloss, or even matte finish paper, then you can texture it with embossing dies after the printing. That way you get a better quality label on a less expensive material."
Embossing is also utilized in industrial applications as well. Parts that go into cell phones are embossed. DMS has a customer who embosses a dimple pattern into a substrate to make it easier to grip. "Another area is low-level security, as in bus passes, where the embossing knocks out the photocopier as a means of counterfeiting," Polkinghorne adds.
"Deeply sculptured embossing gives the narrow web converter an opportunity for an increased competitive advantage. We see the market growing," says Mercer of UEI Group. "It's another decorative effect that can add value in virtually every narrow web market.
"Embossing can show a lot of detail from realistic to subtle, depending on what you are producing. Sometimes you don't want as much detail, but at other times you may want to run a blind emboss, where it is not registering to printing, so that the embossing is carrying higher image detail."
Mercer says that delivery of embossing tools depends upon several factors, "such as the size of the image, the number of images per repeat, the size of the cylinder, the number of sets, and so forth. We're making two cylinders for each job, so there is more engraved cutting time compared to manufacturing a single hot foil stamp cylinder."
David Polkinghorne agrees that the market is good. "We're seeing a bit of an increase as far as the percentage of embossing dies," he says. "Compared with hot stamp dies, it's probably on the upsurge."
Die delivery time depends on the detail involved in creating the image, says David McLaughlin, technical support manager for American Die Technology, Suwanee, GA. "We can do low to moderate detail, high detail, but with high detail I want to evaluate the image to ensure that it will work and be an effective product for the customer. A lot of times we have to make subtle changes, with customer approval."
Steel embossing dies are made in a couple of different ways: CNC machining, EDM (electric discharge machining), and photoengraving. EDM is an electric etching process, and photoengraving involves transfer of the image to the cylinder photographically, followed by chemical etching. Both EDM and photoengraving allow for more intricacy in the embossed image.
Running speeds for embossing dies depend on several factors, such as the design detail, stock and depth of emboss. "We have found, however, that a machine can be run at about 90 percent of maximum running speed when embossing," says Mercer of UEI Group. "There is virtually no slowdown associated with it."
In England back in the last century, Robert Smithson and his father, Keith, noticed that over-impression of photopolymer letterpress plates into substrates would leave an indentation of the image. An idea was born. Their first attempt was on a label for Glenfiddich, the single-malt Scotch Whisky.
Today, Trinity Graphic USA, in Sarasota, FL, and its UK counterpart are making a good living producing photopolymer plates for embossing. Robert Smithson, who runs the US operation, is pleased by the response from the flexographic community. "Last year we got 365 new customers, one for each day of the year," he says. "We have customers in Australia, Japan, India, Hong Kong, all over the world."
"The advantages of using photopolymer plates are many," he says. "The durometer is obviously softer than steel. The plates tend not to break through the substrate as often as metal plates do. And they are very simple to mount inside the press."
The impression, in most cases, is comparable between photopolymer and steel. "The only disadvantage is that you can't get a 3D emboss--different levels on one particular label. With photopolymer it's normally just one height. Otherwise the quality is very similar."
An added bonus is that they can be produced quickly. Trinity Graphic has a one-day turnaround, "instead of two weeks like for some of the metal dies."
The plates are harder than photopolymer printing plates, he says. "When we harden them, we bombard them with two different wavelengths of UV light." The cost less than the metal ones, also. "You will save, the first time around with plates and die blanks, at least 60 percent. If you have a range of labels for the same product, it can turn out to be 90 percent less expensive. The blanks don't wear out, just the plates, and replacement is very inexpensive."
According to Smithson, the life span of a photopolymer plate is quite long. "You should be able to get a million impressions from a set of these plates. Some people get more. One of our customers gets two million."
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|Publication:||Label & Narrow Web|
|Date:||May 1, 2003|
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