Page 257 - Training 2019

Graymills provides a variety of ink pumps for package printing.

The frequency with which inks are being changed becomes an important factor, Shields says,
because certain pump systems are easier to clean and change over. For example, he states
peristaltic pumps are much easier to clean and better suited for shorter runs, as opposed to
centrifugal or diaphragm pumps, which require a full washout to clean. “The cleanability of the
pump is a major factor to consider,” Shields says. “If you’re doing long runs, it’s not as big of an
issue, but if you’re doing 20-minute runs, it’s a huge issue. A five-minute clean job on a 10-hour
run is a lot different than a five-minute clean job on a 20-minute run.” These factors, Shields
explains, lead to certain segments of the packaging industry relying on different types of pumps.
He details that the tag and label segment primarily uses peristaltic pumps, because their easy-to-
clean nature makes them better suited for the short run printing common in narrow-web.
Meanwhile, wide-web gravure printers often utilize centrifugal pumps, primarily because they have
the lowest operating cost, making them a logical choice for long run environments.
Shields also explains that double diaphragm pumps are often used in mid- to wide-web presses,
largely because they’re compact, relatively inexpensive and the wash up processes on many wide-
web presses were designed for diaphragm pumps. One potential pitfall of diaphragm pumps,
Shields says, is they create a lot of high-pressure pulsation leading to “blade clutter,” in which the
doctor blade bends with the pulsation of the pump, leading to inconsistent wiping against the
anilox roll. “People tend to compensate by over pressuring their chambers,” he says. “They really
crank the pressure on their chambers down, so that means you’re not getting a nice gliding action
of the blade on the anilox. You’re actually grinding into the anilox.” Regardless of ink type or
printing process, Shields explains there are rules of thumb surrounding certain aspects of an ink
system. For ink tanks, he explains the run length and how much ink is being put down should
determine the size of the tank. For example, if a job calls for an opaque white background, Shields
states that converters can expect heavy ink usage, and therefore a larger tank should be used.
However, if a job requires a small patch of a spot colour, the required tank won’t be quite as large.
Additionally, he explains that a pump should not be run above 75% of its capacity, as running it at
its limit will increase wear.

Maintaining a Greener Ink
As awareness surrounding food-packaging increases, printers and suppliers need to ensure the
consumables they’re implementing are suited for these applications and meet their end customers’
requirements. Todd Dragoo, technical services director, offset/digital, INX International Ink Co.,
explains that using an ink designed for a commercial application in a packaging application can
become problematic due to odour. Dragoo states that INX International has developed a system
designed to function in a “dual use environment,” suitable for both commercial and packaging
applications, while meeting Nestlé and Swiss ordinance compliance. “I’m trying to encourage
printers to look at these greener ink options to remove potential odour or other material concerns

INK PUMP TRAINING MANUAL 8
Updated - 24 June 2019