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Rotary Dies



Whether its solid or flexible, converters are benefitting from improved technology in their choice of cutting tool, with cost considerations in mind.



Published January 14, 2009
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Rotary Dies



Whether its solid or flexible, converters are benefitting from improved technology in their choice of cutting tool, with cost considerations in mind.



By Steve Katz



Pressure sensitive labels need to be cut into a variety of shapes and sizes. Rotary dies are the tools of the trade converters use to accomplish this task. These cylindrical tools, with their sharpened steel blades, must be precise, consistent and durable in order for converters to count on them to get the job done.

In narrow web label printing, particularly in the North American market, it seems the story on rotary dies is turning into the story about how flexible dies are increasingly becoming the popular choice. Die manufacturers generally report that the die usage in the European label market breaks down to 80 percent flexible and 20 percent solid tooling. Meanwhile, across the Atlantic, suppliers estimate the current split to be anywhere from around 75 percent solid and 25 percent flexible, to a 65/35 split, with flexible dies continuously gaining in popularity. Some say this is the trend, while there are those who believe otherwise, and feel that solid tooling is holding its own. What’s driving the trend in the rotary die market has a lot to do with what’s important to a typical label converter: turnaround times, performance, changeover times, ease of use, and perhaps above all else, cost.

Cost


As the global economic downturn continues, it’s no wonder that cost is playing such a significant role in what label printers are choosing to use in converting their products.


Flexible Dies from Electro Optic
“The flexible die market is an exciting market as it represents the most obvious opportunities for cost savings,” says Markus Marfurt, president, Electro Optic, Alpharetta, GA, USA. “Using flexible dies as opposed to solid tools is just good business. It comes down to cost, and when you add it all up, and include sharpening and shipping costs, it makes perfect sense. We feel an Electro Optic die performs as good or better than a solid tool.”

Marfurt believes that the main reason flexible die usage has lagged behind in the US while thriving in Europe was poor quality. “Since the late 1990s, flexible tooling has become so much more reliable. Mechanical sharpening of our dies was a real benchmark at Electro Optic, which has become an absolute niche for us. We found that hand sharpening just wasn’t reliable. Machine sharpened flexible dies made them highly reliable and acceptable in the American market. And if you look at the market’s landscape, all of the major European manufacturers are now pushing their products in North America,” he says.

One such European company that has made inroads with its US flexible die business is Germany based Kocher+Beck. The company manufactures its flexible dies in Lenexa, KS, USA, and makes magnetic cylinders in Suwanee, GA. Frank Hasselberg, executive VP for Kocher+Beck USA, says, “The US is going more and more to the flexible side of the market. It’s not like Europe – yet. One reason for this is that the US market didn’t have the quality of flexible dies that Europe has had. But now European tooling technology has come to the US, and the market is rapidly growing due to the quality of products being produced.”

It’s not just European based suppliers who are acknowledging the trend. Wade Fouts, VP of sales for Wilson Manufacturing, St. Louis, MO, USA, feels that economics is a driving force behind the growth of flexible die usage in the US market. “The penetration of flexible dies within the US has grown significantly over the past five years, and the key reason for this transition is cost reduction,” he says.

While cost seems to be the predominant reasoning behind the market going flexible, it’s important to note that an initial investment in a magnetic cylinder is the first step, and a costly one at that.

“A flexible die can indeed provide significant savings as long as you have the magnetic roll required for the repeat length you need to achieve. If you have to purchase the magnetic roll as well, then the savings are not there,” Fouts says.

Fouts also points out that cost savings can be found by looking into the nature of the production processes of flexible versus solid tools. “The production of solid dies is very labor intensive in comparison to flexible dies. Not only that, but steel is purchased by the pound, so there is an obvious savings there as well,” he says.

Steve Burleson, group director of marketing and strategy, Gerhardt International, says, “Flexible dies are growing exponentially within North America, especially in the digital printing segment, where it’s only flexible dies that can be used. In the US, we no longer manufacture solid dies. We’ll still make solid dies in Europe, when the thicker substrates call for them. But for our label business, it’s only flexible.”

Burleson points out that storage and shipping are other areas where money can be saved by going flexible. “Flexible dies take up considerably less storage space. Money is also saved in the costs of shipping the dies. You can overnight a flexible die for $20,” he says, adding that solid tools, which are heavier, cost significantly more to ship.

Burleson says that Gerhardt has decided to put its technology and resources behind its flexible die business, and notes the role the current economic slump has played in the company’s perspective. “The economy is actually helping us out, as more and more converters are looking for more ways to reduce costs,” he says.

Magnets


While die suppliers talk enthusiastically about long-term cost savings from making the switch to flexible dies, it’s important to point out that the significant, initial investment in a magnetic cylinder is the necessary first step in the process.

Frank Hasselberg of Kocker+Beck notes that this investment is a big leap for converters. “The magnetic cylinder itself typically costs twice as much as a solid tool. To make it cost-effective, converters have a number of jobs with the same repeat length of the cylinder. Typically, when a customer buys a new press, they’ll order 12" and 16" cylinders to cover their most common repeat size.”

While some die manufacturers make their own cylinders, there are also companies that specialize solely in magnetic cylinder production. These companies make for a good resource in terms of providing information on the growing flexible die market, new technology, as well as why magnetic cylinders are a good fit for the label industry.


A Modular Magnetic cylinder from TD Wright
David McEachern, president of TD Wright, a magnetic cylinder manufacturer based in St. Paul, MN, USA, says, “We’re seeing more and more interest from people working with flexible dies. I think a reason the market’s growth has been so steady is because the dies have become higher quality, as well as it being so cost effective.”

McEachern emphasizes the importance of using a reliable magnetic cylinder for label diecutting. “Label cylinders have to be very durable, especially in strong repeats. As the repeat gets smaller, a greater proportion of the magnet is used. This prevents the dies from slipping.”

The company offers 100 percent rare earth magnets, but McEachern says it’s not quite necessary in label converting as the forces needed are smaller when compared with cylinders used for other types of converting. He also sees label converters often engaging in a certain unnecessary practice, when they’re not confident in their die and cylinder.

“The label guys, for some reason, are putting tape on the dies when attaching them to the cylinder. We don’t know why. With our 100 percent rare earth cylinders, we guarantee no slippage. If a converter is using tape, then that’s not good enough,” he says. “The magnet is supposed to do all the work. What we’ll do is raise the power of the magnet on the lead and the tail. If you use a powerful enough magnet, it just simplifies everything.”

TD Wright features a patented design called Modular Magnetic, that McEachern describes as having something similar to a checkerboard pattern. “Conventional cylinders are made with the magnets in rows, and this leads to ‘creep.’ Sooner or later you’ll be out of register.”

Mike Wilks, director of marketing and sales, Bunting Magnetics, Newton, KS, USA, says that when it comes to cylinders, “There are a lot of things that people don’t see. The strength of the neodymium (a rare earth metal) costs a lot more money. It’s five times stronger than ceramic. We can use rare earth on the edges to keep the die tight and use ceramic in between,” he says, while also cautioning that if the magnets are too strong, it can kink the die.

He says Bunting’s X-treme Cylinders are products that have been popular among the company’s label converting customers. “It’s a cylinder we take extra care in grinding to increase the total run out.”
Bunting Magnetics’ recent activities illustrate how the flexible die market is growing. “We make magnetic cylinders, have launched our own line of flexible dies and have opened a new 11,000 square foot facility dedicated solely to our line of dies. It’s taking over our customer base,” Wilks says, and predicts that “over the next three to five years, flexible is going to overtake solid dies. It makes all the financial sense in the world.”

Wilks says Bunting uses a CNC (computer numerical control) mill designed solely for sharpening its flexible dies. “This ensures the accuracy of our dies. We manufacture only 100 percent machine sharpened dies.”

Wilks says that Bunting’s X-treme line of products are particularly popular with label converters. “With tolerances that mirror those of the tight tolerance X-treme cylinder, X-treme dies only need to be machined on one side,” Wilks says. “No back grinding is needed to hit tolerances. The result is a better die edge produced more efficiently with the accuracy you can only get from an X-treme die.”

 
CNC solid die manufacturing at RotoMetrics
 

Solid as a rock


“The rotary die market is alive and well,” says Steve Lee, VP of RotoMetrics, a global manufacturer of both flexible and solid dies with headquarters in Eureka, MO, USA. Lee says that in many cases flexible dies are the best tool for the job, but for those who claim solid tools will become a thing of the past in the label business, well, Lee feels that that just isn’t so.

 
“The flexible die market has grown significantly, but our customers understand that choosing the best tool ­– flexible or solid – for each unique application helps them achieve maximum profitability,” Lee says, adding that he doesn’t think the prognostications that flexible is going to overtake solid dies will ever come to fruition.

“In the beginning, when flexible dies first entered the US market, some people said a transformation was going to take place. The people saying this were the ones who don’t manufacture solid dies. There are many applications where solid tools are preferred and the most economical choice. The same holds true for flexible dies as well,” Lee says.

“There will always be a need for engraved tooling,” says Bob Potratz, sales manager, Action Rotary Die, Addison, IL, USA. While also acknowledging the headway and momentum of the flexible die segment of the market, Potratz says the company is still moving forward with its engraved tooling business.

“A big portion of our market is with fabricators. We’ve been able to offset the loss of business from people switching to flexible dies. We saw the need to reinvent ourselves,” he says.

Potratz points out that Action Rotary specializes in through-hardened tool steels, which he says is ideal for cutting difficult materials. “Solid tooling is needed to cut more complex, difficult substrates. There are certain materials that cannot be cut with flexible tools. There are limitations,” he says, noting reflective and abrasive materials are examples of heavy duty, demanding diecuts that flexible dies can’t cut effectively.

“It’s all about price these days, and that’s the reason magnetic dies have become so popular. Flexible has taken a big share of the market, but there will always be limitations,” he says.

“Our customers can have their tool steel dies cryogenically treated (deep frozen), which leads to extended die life,” Potratz says.

Depending on the complexity and diameter of a die, Action Rotary delivers its tool steel dies to customers within a week, and Potratz acknowledges the steeper price tag of these dies. “There are a lot of benefits to using tool steel, but it is often a longer process and more expensive to produce. But, it’s worth the wait.”

Action Rotary Die also offers induction hardened steels to its customers. Potratz says that dies manufactured with these steels offer superior turnaround times. “The diversity of steels allows us to be responsive to the many challenges that a converter has,” he says.

To sum up Action Rotary Die’s thinking in the changing die market, Potratz says: “Die manufacturers live in a world of perfection. Our core strength is our tool steel, and it’s a winning formula.”

Mo Azim, vice president, Atlas Die LLC, Wood Dale, IL, USA, also feels strongly about his company’s solid die business. “I don’t think solid tooling is going away, especially with some of the deeper engravings and the thicker, dense materials. Solid tools have also come along way, now that they’re being heat treated.”

Azim acknowledges the allure of the potential advantages flexible dies offer in terms of lead times, but at the same time says the company’s solid tool products can also be sent out pretty quickly, saying, “We can turn out our solid tooling in a day or so.”

Seeing the importance of making both solid and flexible tools, Atlas has been active in recent months with acquisitions, accomplishing the goal of having all its bases covered when it comes to die options. “One recent acquisition of ours is a New Mexico based company called Xynatech, who’s solely producing flexible dies, for now. We also acquired the assets of BTS. They were solid tooling manufacturers and recognized that flexible is here stay. They were struggling not being able to offer both,” Azim says.

Wilson’s Wade Fouts says, “Solid tooling demands will forever be present. Not all materials can be converted with flexible dies. Levels of hardness and durability achievable with solid dies are not attainable with flexible dies when converting abrasive materials, therefore, some materials are not good candidates. With that said, it’s very difficult for a solid tool to compete with a flexible die when converting standard substrates, especially when smaller label quantities are involved.”

Sharpening


Once upon a time, all dies, both flexible and solid, were hand sharpened. Some feel that hand sharpening is an antiquated, counterproductive technique.

Markus Marfurt of Electro Optic believes that the advent of machine sharpened dies has been instrumental in flexible’s increase in popularity. “Machine sharpening is the technology that made flexible dies as highly reliable as they are today. This in turn made them an acceptable option for the American market. Machine sharpening offers much better control and is more precise. It allows for the ability to ensure exact angles.”


A up-close look at the blade of machine sharpened Wilson die
Fouts is also a machine sharpening proponent. “Machine sharpening is premium over hand sharpening. Consider the facts: Machine sharpening produces a precise, constant, dead-sharp blade along every inch of a die, unlike hand sharpened dies, where sharpness varies throughout, depending on the human sharpener, the intricacy of the pattern and the number of times the die has been sharpened previously. Each and every time a die is sharpened, the included angle of the blade grows and as a result the label yield is reduced.

“For example, if a new die produced 1 million revolutions and you have it resharpened, the next run will last an estimated 800,000 revolutions, then another resharp – 600,000 revolutions, and so on. Machine sharpened dies last longer right from the box and the revolution count will not decrease after resharpening. The machine sharpened die will produce a much greater yield over its life span when compared with hand sharpening. We machine sharpen our solid and flexible dies with the same technology. The only die makers that don’t favor the machine sharpening process are the companies that don’t have the ability to produce them,” Fouts says.

Steve Lee says RotoMetrics’ dies are mostly machine sharpened. “Overall, a machine sharpened die is a more accurate tool,” he says, but explains why there’s still the need for the craftsmanship of a hand sharpener. “There are thousands of dies in use today that, initially, were hand sharpened. Once a die has been sharpened by hand, it is not cost-effective to switch to machine sharpening.”

Steve Burleson of Gerhardt feels that by being machine sharpened, flexible dies provide inherent advantages. He says, “Flexible dies have advantages in industries that require tight tolerances like pharmaceuticals and food. Flexible die sharpening is a machine automated process; they can’t be sharpened by hand. The human element is removed. Anytime you can automate a process you’re able to reduce costs and increase tolerances,” he says.

Burleson notices the converting trend of using increasingly thinner materials. “Converters are thinking ‘the thinner the better,’ so dies have to be extremely precise, and the technology continues to evolve. In order to reduce manufacturing costs, you’ve got to be at the forefront of technology, not just with the dies being used, but all parts of the production process.”

Mo Azim of Atlas points out that both hand and machine sharpening have their own distinct advantages. He says, “Machine sharpened dies have the advantage of being more consistent. But hand sharpening can provide steeper angles where machine sharpening can’t hold up.”

While many suppliers are believers in machine sharpening, especially those in the flexible segment, Action Rotary’s Bob Potratz isn’t one of them.

“The craftsmanship of a hand sharpener is still the way to go. We’re looking into machine sharpening and we see the struggle. There are impurities in steel – inconsistencies and weak spots – that machines are unable to pick up on,” he says, adding, “I know there will always be a need for hand sharpening. In today’s competitive marketplace, you always have to be on the lookout for adding value to your product. Our company will only offer machine sharpened dies once it has been perfected,” Potratz says.

Storage and care


While the end result may be the same, there are some glaring differences in practice when it comes to flexible versus solid tools. By nature, a solid tool is a heavy piece of steel and in contrast, flexible dies are extremely lightweight. The weight of flexible tooling is found in the magnetic cylinder. So, proponents of flexible tools point to their ease of use when comparing flexible to solid. But their point is only so obvious when the size of the cylinder doesn’t change from job to job.

“Flexible dies are so much easier to change on press than solid tooling,” Bunting’s Wilks points out. “If the next job requires the same repeat as the previous, it’s just a matter of changing the die. The cylinder stays in place.”

Flexible die proponents are quick to point out the way the dies are stored is an advantage over solid tools.

Mike Wilks says, “Most dies are wrapped in a corrosion resistant paper. Converters will save the paper for re-wraping the dies, and the paper will keep the die from rusting. Most dies will not corrode, even if they’re not wrapped up. We coat ours in nickel, which insures that they won’t deteriorate. Simply put, it’s easier to store flexible than solid dies, and I think it’s one of the reasons Europeans have made the transition that much sooner,” he says, pointing out that European manufacturers are generally more space-conscious than those in North America.

Frank Hasselberg emphasizes the importance of keeping the dies in pristine condition, free of the substances they come into contact with. “Converters need to make sure there is no debris on the surface of the cylinder or the die itself. It’s important to clean the die of glue or adhesive, and then stored,” he says.

Action Rotary’s Bob Potratz also talks about what converters can do to preserve the life of a solid die, in particular. “There’s a direct correlation between how much you get out of the die and how the die is handled. How a die is cared for goes a long way in determining how long it will last. This includes how a die is installed in the press and the amount of pressure that is being exerted on the die,” he says, and also points out that storing dies in a humid environment can be a factor, as it can lead to rusting. “Optimally, a die should be kept in a controlled environment.”

When it comes to the care and storage of dies, RotoMetrics has an educational program in place for its customers. “Our representatives visit customers at their facilities and provide in-house seminars on a routine basis,” Steve Lee says.

Life and times


When a label converter’s customer places an order, they are usually looking to have that order filled as soon as possible. So, when it comes to supplies – labelstocks, adhesives, inks, and in this case, dies – lead times are important, and a pretty good selling point. Die makers are reporting faster lead times as another advantage flexible dies provide.

Many flexible die manufacturers report the capability of shipping a flexible die overnight the very same day its ordered. Solid tooling manufacturers can’t lay claim to having that ability. When it comes to “print-on-demand,” flexible has a leg up.

How long a die will last before it needs to be replaced or resharpened certainly is something converters think about, and suppliers are willing to chime in on the topic. While some say that, in general, a flexible die needs to be replaced at about the same time that a solid die would need sharpening, the answer is not so cut and dry.

Steve Lee of RotoMetrics feels it’s not possible to sum up a die’s life expectancy. As far as how long a die will last, he says, “It really depends on what you’re cutting. It depends on the types of inks, coatings and substrates being used. A die’s life is dependent on the specific situation.” 


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