They are small and heavy and expensive, and they are changing the industry. They have been around for decades, but until a half dozen years ago they were rarely employed in narrow web machinery to print and convert labels. They are servo drives, and they are now a popular item on high end presses.
“Servo, or electronic, drives are now becoming the norm rather than the exception due to the recognized benefits that can be achieved,” says Federico d’Annunzio, managing director of GiDue, press manufacturer based in Turate, Italy. “We now see press manufacturers in Italy, the US, the UK, Denmark, Germany, the Czech Republic, and Spain all adopting this technology.”
“A lot of converters are looking at servo driven presses and asking a lot of questions,” says Ken Daming, director of product management at Mark Andy, Chesterfield, MO, USA. “There are two basic markets: Small and medium sized converters will continue to buy smaller, mechanically driven presses and be satisfied with the products that they produce on those machines. But the higher end presses all have servos, and they are now very well accepted. The higher end converters, who have their businesses tuned to high productivity, will buy that technology.”
“Customers are demanding servo drive technology now,” says Terry Trexler, product manager for Gallus Inc., Philadelphia, PA, USA. “They have become better educated customers. They have heard the lectures. They have heard the machine manufacturers say servo, servo, servo. And they have come to the conclusion that yes, it is a better system.” Gallus introduced one of the first narrow web servo drive presses, the RCS 330, in 1999.
“There are two sides to this,” says Jakob Landberg, director of sales at Nilpeter, Slagelse, Denmark. “At this stage, servos are still relative newcomers to the narrow web business, and the prices are relatively high. That means that if you look at servos they are mainly in the top and middle segments of the market.
“And there are two types of customer: one who isn’t concerned how the press runs as long as it delivers what he wants, and the other who likes to be in the forefront of development. Thank God for both of those.”
Servo drives have been driving machinery for many years, but in printing they have been in use only on wide web machinery until the late 1990s. But because the cost of servo drives has been coming down, they can be employed in narrow web presses — albeit the more expensive ones — to greater and lesser extents today.
Jim Flynn of Gallus changes the job on a print station while the servo press — the RCS 330 — is running.
The print cylinders on conventional mechanical presses are connected via gears and other linkages to a main shaft. In a servo drive press, the servo motor is affixed directly to the print (plate) cylinder and the electronic signal that drives the servo also drives the cylinder — directly and with no linkage or intervening parts of any kind.
“A mechanical press is only as good as the day it rolls off the assembly line. It continues to degrade from Day One. It is never as good a press after the first day you run it.” That’s the opinion of W. Spencer Spaulding, president of GraphixOne, Cincinnati, OH, USA. GraphixOne, a custom engineering and equipment rebuilding company, recently introduced the PROflex press for the narrow web market.
Joseph Drilling, president of MPS North America Sales & Service, Milford, OH, says that top managers at converting companies are hearing the buzz about servos and are sending their operations people to him to examine MPS presses, which are manufactured in the Netherlands by Multi-Print Systems. MPS, which makes only servo driven presses, was another early entrant in the market, producing its first machine in 1999.
So what’s the attraction? Why servo?
“When the technology first came into the narrow web marketplace, there was a bit of hesitation, because some pretty big claims were being made about what the technology would do,” says Jim Hulman, business development at Bosch Rexroth, Hoffman Estates, IL, USA. “This reaction is the same in any industry that implements servo drive technology. Once you get past that and trust it, you find out.” Bosch Rexroth is the global leader in the manufacture of servo drives with a market share greater than 50 percent.
“By getting rid of mechanical limitations you can take machines up to 700 feet per minute. You can start looking at combining processes: a printing section up front, diecutting, folding gluing, palletizing, on the other side, all connected by servo drives. You can cut, fold and palletize and never touch a human hand.”
Nilpeter’s FA-Line servo press
“This is a cliché, but it’s the right one: The race is won or lost in the pits,” says Trexler. “Where the servo drive really shines is in the pit. The makeready is fast, and there is little or no wasted substrate. The press gives the ability to pre-register, to start the press almost in perfect register. It comes with the ability to run the job once, and the next time you can recall all those job settings electronically and run it again immediately.”
Those advantages — swift makeready, less waste, quick and accurate registration — are few in number but high in importance in the press room. Together they can make a difference in the amount of work that a press produces in a given period of time.
“The most obvious benefits,” says d’Annunzio, “are superior register and tension control, which results in a reduction of waste. Because a servo drive is essentially a digital drive, the demands on both operators and management are significantly reduced since print parameters of each run can be stored in a digital file, which can then communicate with a company’s MIS system and further linked with a visual inspection option.”
The PROflex from GraphixOne
“And re-registration: Occasionally someone will want to run a web through a press twice, and the servo driven press allows that through a combination of the servos and other electronics — the control system.”
The speed and ease of registration leads directly to the substrate waste factor. “The press is brought into register much more quickly with a servo press and therefore the waste is lower on startup, usually one press length. A typical mechanical press could take three to four press lengths,” Daming adds.
“We hear various figures on reduced waste,” says Spaulding. “It varies from operator to operator and from press to press. But overall, the setup is faster. You are in register just so much more quickly, producing sellable product much faster than before.”
According to d’Annunzio, the steadily increasing width of narrow web presses, coupled with the rising print speeds sought by today’s operator, call out for servo performance. “Today it is common to see narrow web presses printing and converting a web width of 500 to 600 millimeters (20" to 24") at speeds up to 180 meters per minute (600 fpm). These press speeds would be a problem with gear driven presses.”
He sees still more advantages: “In addition to increased register and tension control, servo technology enables the converter to more accurately repeat a given job, manage color density and minimize setup times and waste. Further, the use of servo drives eliminates the age-old problem of gear marking caused by incomplete meshing of cylinder and roller gears. This allows many converters to process a wide range of substrate callipers without the need to make time consuming changes to press drives.
“Additionally, an increasing number of presses we supply incorporate combination printing and converting. The marriage of flexography with screen, gravure and lithography provides our customers with a greatly increased converting capability. Here servo technology is a natural fit. All of these factors drive the move to digital printing and converting that is specified by shorter runs, quicker changeovers, greatly reduced lead times and an overall improvement in supply chain management.”
“One of the nice things about servos is that they don’t know or care which way they are running,” says Spaulding. “You can reverse a print unit without large gear boxes to change the direction of the line shaft. The noise factor is another thing: Servos are extremely quiet.”
A huge forward leap that servo technology gives to the narrow web printer comes in the form of electronic intelligence. If servo drives are big muscles, they are connected via a neural network of wires to a computerized brain and controlled from there.
“Electronics have changed the skills you need in-house,” says Landberg of Nilpeter. “You have to have good electronics people.
“Our presses are equipped with a control system that you can connect to your company’s network and collect job data. You can save all job data, all processes, for re-running any job. We have done that on mechanical presses, but the adjustability on a servo press is much greater.
“If you run a job,” Landberg continues, “and you want to run it again, you put all of your press parameters — tension, speed, substrate — into the memory, and recall them when you want them. The advantage, of course, is that you get your printing cylinder in the right position before you lower it down onto the cylinder. There’s a lot less waste.”
“The job memory allows for the creation of job setup recipes,” says Drilling. “You can include your web tension, print repeat settings, web velocity for the ideal pitch line matched to plate roll speed for a frictionless printing position on a wide range of substrates.”
Does this particular capability of the servo press — digital memory allowing for fast makeready — make the servo press more appealing to printers of short run work?
“Yes,” says Trexler. “It has more appeal to the producers of short and medium run jobs over the longer runs. The more jobs you can run, the more the technology is in your court. Over the last 10 years the order sizes have become smaller, the labels are more diversified, and servo now gives you the ability to print those 900 labels a week and afford to do so. Servo drive technology is lowering the short run figure, the number of labels it takes to make money on a short run job.”
“With a servo press, if you have very long runs of the same job, your savings in material and time is less than if you have many jobs per day,” notes Jakob Landberg.
The press manufacturers and their customers are also pleased with another feature that the servo press technology offers: the ability to troubleshoot the press remotely, to go inside it by the use of a modem.
“We can connect globally,” Landberg adds, “from our facilities in Denmark and the US we can go into all the servo presses that we have installed around the world. We can adjust the parameters, we can fix electronic errors if we find them. We can upload software.”
“The cost of a servo drive is coming down and down,” says Daming. “It has not reached the point where the line shaft and gear boxes will be abandoned, but in less than 10 years servo motors will become more commonplace in the whole range of presses. And I don’t think that people are afraid of the technology. The small companies and the mid-range converters will embrace the technology if it demonstrates performance improvement.”
“These are the cutting edge customers, the ones who are getting the servo presses,” says Trexler of Gallus. “And we have a lot of new customers, new business we have never had before. They are all asking about servos.”
“There is no doubt in my mind that the future will see continued and expanded use of electronic drive technology,” says d’Annunzio. “The market will demand this.”