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November 25, 2013
My prepress supplier said he could enhance our color gamut with GCR , what is this?
G.C.R. is an acronym for Gray Component Replacement and when applied by an experienced prepress provider can
greatly increase the gamut of color and hue that a printer can achieve. This
removes most of the gray type areas from each color and adds it to the black
plate, which will help maintain the definition of the original image and at the
same time gives the operator much wider latitude to achieve strong vibrant
colors. This in effect removes neutrals that were once three colors and
puts them all onto the black printer, which will help maintain hues and
color throughout the run.
October 29, 2013
What are the benefits of helical and spur gears?
majority of gears you generally see are spur gears. They are easy to identify
as the teeth of the spur gear project radially and are parallel to the axis of
the gear, with the teeth being exactly perpendicular to its flat faces.
They are simple to make and are actually more efficient if compared to a
helical gear of the same size. The efficiency of the helical gear is less
because helical gear trains have sliding contacts between the teeth that in
turn produces axial thrust of the gear shaft and generates more heat, which
causes it to lose some of its efficiency. The teeth of helical gears are not
parallel to the axis of the gear, and are set at an angle. Since the surface
that the teeth are made is cylindrical the teeth create a helix shape. Because
the teeth of helical gears engage a little at a time they create much less
noise and can be used to transfer power between non parallel shafts. Helical
gears can handle more load than spur gears because a helical tooth is larger
due to its diagonal position. When you need a simple design, where speeds are
lower and noise does not matter, then spur gears are ideal. If you want a
quieter machine, with higher speeds and accept a more complex design then
helical is the better choice.
October 18, 2013
What can we do to reduce pollution from our Flexo facility?
Preventing pollution in and
around any manufacturing facility is a legal requirement, so trying to prevent
it occurring in the first place should be your first goal. You should emphasize
the importance to your operators and managers alike that keeping all work areas
clean by minimizing spillages and making sure they are cleaned up immediately
is a simple but effective way of reducing a great deal of pollution in the
immediate area of the press room.
Always calculate as accurately as possible the amount of
materials you will need to produce a job as leftovers often end up not getting
used, all of which must be disposed of at some point. There are many less toxic
solutions available and if you are not sure, ask your supplier.
When using any
materials, try to use the oldest first so that they do not become obsolete again,
resulting in the need to dispose of them. For product that has specific
disposal requirements, always consult your supplier or local Environmental
department. Always store materials and solutions and provide adequate
containment to ensure that any leakage or other waste cannot get into the
Washable rags are a simple way of reducing waste paper having to
be disposed of and, where possible, using
water or UV inks will dramatically reduce your solvent emissions. For any waste
that you do generate at least take the time to segregate them to make them
easier to recycle.
line: prevention is far better than treating or disposing of hazardous waste so
try to determine if you can use an alternative, less hazardous, product or at
least limit the use of more hazardous items that you have no option to use
because of their unique features. Even if it is customer specified, if you can
find a safer, less hazardous, product they may be willing to allow this to be
used. The most critical factor is to involve everyone in your company, your
suppliers and as just mentioned even your customers if you are to reduce your potential
September 12, 2013
We seem to be hearing more about LED UV cured inks being the future for many markets. Do you agree with this and what are its pros and cons verses conventional UV inks?
There is no doubt that LED UV curing systems offer some
tremendous advantages with their ability to switch on and off and hence no need
to warm up or cool down, giving the printer tremendous productivity advantages.
This in turn leads to much longer lamp life, (Potentially 10 x longer than
typical mercury lamps), and considerable less maintenance needs, as they do not
need shutters or fans. LED cured inks do
have to be specially formulated and just like the conversion from water to UV
will take time for the variety and volume to become available on a global
Another major advantage of LED technology is its much lower energy
requirements so much so that it is at least 50% less than conventional UV. Environmentally, LED also leads the way not
just with less power consumption, but it also does not use mercury and being cool
does not generate any plasma. From a safety perspective the lamps are always
cool to the touch and do not create a short wave, meaning less risk to
the eyes and skin of the operator. As with all new technologies it does
presently cost significantly more to purchase but based on its many benefits
its payback could be in less than 12 months for most printers.
April 19, 2013
We have recently installed a Flexo press but my prepress department is telling me I cannot use our existing gravure separations to make Flexo plates from. Why not?
This is a common dilemma for many companies and designers
alike wanting to move into the flexographic field. There is no doubt that Flexo has come a long
way and is capable of producing some very high quality print but it does have
certain limitations that have to be taken into account at the design and color
Unlike gravure Flexo does have some dot gain that can create
problems in creating soft gradients, vignettes and it does have a limit to the
size of dot it can hold. This means that an allowance has to be built into the
screening of artwork separations for a Flexo plate to be able to hold it up and
to allow for the dot gain that is inevitable even with the best press and
Registration is another challenge, and inevitably means more trapping
is needed than for the same gravure printed image. All this said, Flexo’s
ability to print on any substrate, its speed of interchangeability of plates
and variety of ink systems, all at an acceptable price even with short runs, is
what I am sure led you to add Flexo to your
April 3, 2013
How essential is daily/weekly cleaning of a press and how much does it really affect our bottom line?
It is this sort of question that probably answers why I see so many presses
in such a run down and poorly functional condition. If you are running your
equipment continuously, as most companies do, the gradual build-up of ink, paper
dust, grease and other contaminates will eventually overwhelm most key
components on your press such as gears, bearings, drive shafts, belts, and pulleys. The problem is this can take a while and causes the operator to have to
make daily adjusts to the operation of your machine. This will lead to slower speeds,
more make ready, reduced print quality and higher waste, all of which will affect
your bottom line.
It is vital to make time each day and every week for proper
maintenance and cleaning of your equipment and its key components. It is the
responsibility of management to understand that good housekeeping practice is
essential to maintaining a consistly profitable business and is not something
that can be overlooked or ignored. Sooner or later it will, as they say, “stop
the press” and instead of a few minutes or hours to make a repair it could take
several hours or even days if the fatigue and wear is serious enough. So, how
much does it affect your bottom line? In every way and then some!
March 24, 2013
What is the most effective way to improve our bottom line that doesn't entail a huge capital investment?
| In my opinion if you were to improve your general housekeeping of your press room but in particular your anilox, you would be able to :
Reduce Down time
Reduce Set up time
Reduce set up material
Reduce ink costs
Reduce roll replacement costs
Improve print quality
All of which will lead to an improved bottom line, but it takes a real commitment and the use of the right cleaning solution and equipment to achieve more consistent ink transfer from the anilox to the plate to the substrate. Whenever I do plant evaluations I invariably find that housekeeping is a low priority and is not taken seriously by many management teams. They claim that it is important but there seems to be little or no real accountability other than to blame the press operator. So please do take a look at your cleaning procedures and if you are not sure what to use, ask your vendors as they will be pleased to help.
March 11, 2013
We are plagued with scoring on our anilox, what are we doing wrong?
After plugging of the anilox cell, scoring of the anilox surface has to be the most common issue that all printers have with their anilox rolls. Unlike plugged cells however, which can be cleaned and in so doing regain their volume, a score line in the surface of an anilox cannot be removed and in effect requires the roll to be reworked.
With this said, it is therefore paramount that everything possible must be done to reduce the possibility of scoring the engraved surface of your anilox. Notice I said "reduce the possibility", this is because a great deal of scoring comes from contamination within your ink or coating. Even if you have filters and rare earth magnets in your ink lines, it is difficult if not impossible to remove all metal, pigment/resin clumping and paper dust particles all of which can and do get trapped between the anilox and doctor blade. This will drag the particle around the surface of the roll, which can and will cause score lines of varying degrees. The irony is that you do not have to dig a groove into the surface coating to have it show up on your print, just dragging a hard particle across the surface of the anilox will change its surface characteristic, which in turn will be reflected in a different color density in the form of a light or dark line.
Doctor blade pressure and angle are also very critical. Too much pressure and too acute an angle will cause the blade to begin to wipe from the back of the blade, which increases its surface area, compounding the issue of potential scoring of contamination digging into the roll surface. You need to make sure that the blade is parallel to the anilox surface at set up, that there is no dried ink on its edge, and that the roll is inked up adequately before the blade is presented to the roll.
Too much pressure on the doctor blade, particularly plastic blades, can lead to the blade softening, which can trap hardened particles in it that, in turn, can and will lead to scoring of the roll surface. I strongly recommend that on receipt of your newly engraved anilox that you wash it thoroughly to help remove any remaining ceramic particles, and that if you chip the edge of the roll you fill it immediately to help reduce further ceramic particles getting into the ink and again getting dragged around the surface of the roll.
Remember ceramic is inert, cannot be pulled out with magnets and is very difficult to filter out, and other than diamond can cause dramatic damage to the engraved surface of your roll. So, as you can see, there are a lot of potential causes of scoring and while difficult to eliminate can be significantly reduced with a better understanding of its root causes.
February 26, 2013
Is XG really the answer to Flexo finally being recognized as an equal to offset and gravure printing?
far, flexo has tried simply adding more colors to extend its spot color range
and for a while has had some success with 7-color printing. This has now been
extended into 4-color process printing by running higher density CMYK and has
shown some remarkable results for the few that have tried it.
ink transfer from many photopolymer plates has proved such an issue that
texturization of solid plate surfaces has been used to help it achieve greater
densities. Special software programs and new plate
materials are helping the process significantly and can be very productive on
press with fewer color changes, wash-ups and reduced ink costs. That said, it does
not appear so far to replace all spot colors but is producing gamut ranges that
are challenging offset and gravure. Will it ever be seen as an equal? It
really depends on the buyer and ultimately the consumer's expectations.
January 2, 2013
What are the benefits of LED technology; can they cure my existing UV inks?
(light-emitting diodes) emit light when subjected to an electric current. The
light that is generated consumes very
little energy, and the diodes have an extremely long working
life. One major benefit is they do not generate any ozone, unlike conventional UV lamps
with mercury tubes. A typical LED-UV lamp system consists of numerous LED
panels across a given press width and have multiple rows. The substrate can be
very close to the LED panels since very
little direct heat is generated.
Conventional UV lamps requires
a warm-up phase before they can operate; LED-UV lamps has no waiting time and
are ready to use immediately when they are switched on. LED-UV lamps only produce a small
range of the conventional spectrum of UV lamps and have no high-energy IR radiation or hazardous UV-B and UV-C radiation. LED UV cannot cure conventional UV inks due to the narrow
wave length window of the LED-UV lamp, which peaks at 395 nm. It should be
noted that being a new technology you will find the LED lamps and inks more
expensive than your conventional UV technology. That said, the lower energy consumption
(claimed at up to 80%), reduced need for sophisticated air exhaustion systems and
their perceived safer operation for the operator and others around the printing press makes it a technology
very well worth while considering.
December 3, 2012
How many types of print cylinders are there, and which is the most accurate?
Probably the best know print cylinder is the integral shafted cylinder.
While the most rigid and most accurate over the years has the journal shaft, running completely through the tubular core, it is also much heavier as a result when compared to the stub shafted design. The stub shafted integral roll journals are heat shrunk and often welded for added strength but are more susceptble to deflection, which in turn can lead to a lot more plate bounce. Its major benefit however is that the roll is much lighter and cheaper to build, which makes it more popular.
The next type of plate cylinder is a tubular core with a shaft that it can be mounted on and off. Original designs used tapered cones and lock nuts but have been largely replaced with more modern expandable shafts that use hydraulic or pneumatic expansion of the shaft to lock it to the inner bore of the core.
Finally there is probably the most popular which is the air cylinder. In most cases it looks just like a normal plate cylinder but has a hole drilled usually in the header on one side of the cylinder and 3-4 smaller holes drilled through the outer shell of the core with perhaps one other in the center. Plates are mounted on a sleeve consisting of polyester, fiberglass, carbon fiber or a combination of these materials and is slid onto the outside of the cylinder after air has been pumped into the cylinder from the header air valve. The air escaping from the smaller surface holes on the cylinder creates a cushion of air that the sleeve can slide over and locks into place once the air supply is stopped. Due to the action of sliding the sleeves on and off the cylinder, and the likelihood that dirty, moist air very often is put through unfiltered air lines, these cylinders are prone to scratching and corrosion and as a result will usually need refurishment and even replacement after several years of regular use.
The tubular demountable cylinders can be very accurate but great care needs to be taken to ensure that the shafts are not bent or scratched during installation and removal. Of the two shafted integral designs, the straight through shafted is the most durable and accurate but this often gets overlooked in today's rush to reduce weight and cost but if you are willing to make the initial investment as well as the right lifting equipment, they will last you a lifetime if properly maintained and looked after.
November 5, 2012
Could you give any further explanation of what type of ink measuring cups are best to use in the flexo process?
| It seems that viscocity measurement is once again a popular subject, as it should be considering the impact it can have on print quality and ink consumption. There are a number of measuring cups used today dependent on the application, although they are all known as efflux cups. All are metal cups that contain a given amount of ink or other solution and each has a hole at the bottom. The ink or coating is measured in seconds in regard to how long it will take to drain through the hole, which in turn gives a viscosity reading. Two types of cups are most popular in the flexo industry: the Zahn and the Shell cup. Both have a hole at the bottom but the shell cup has a 1-inch tube attached to the drain hole. Maintaining the size of the cup and holes are critical to achieving accurate measurements so keeping them clean is fundemental to this. Both cups are made in a variety of sizes but generally you should use one that measures between 20-40 seconds. The most common types used is the No. 2 Zahn and the No. 3 Shell cup although as mentioned in a previous answer the DIN No. 4 cup is also gaining in popularity with some printers.
October 24, 2012
What is (ITR) technology, and how can it benefit my company?
“ITR”, otherwise known as “In the round” is the generic term
that has been used for a long time to describe any image that has been produced
around the circumference of a plate cylinder or sleeve in either a photopolymer
or elastomer covering. The technology has been used primarily in Europe for more than thirty years with elastomer coatings being vulcanized, ground and directly
laser engraved onto sleeves and integral rolls. While plate material has and
still can be exposed in the round and is classified by some as “ITR” , I
personally only classify it as true “ITR” if the material has been bonded or
vulcanized to the sleeve or roll circumference and engraved or washed out while in a continuous format. As to the benefits of true “ITR”
there are many ranging from dramatically increased press speeds, improved print quality, improved
registration, more uniform densities, less dot gain, less bounce, reduced
waste, improved productivity, improved profitability, less set up time and less
October 11, 2012
We hear so much about best practice being necessary for good quality print but how do we define what is best practice?
This is a
very big subject but for me best practice is about eliminating as many
variables as possible on and around the press. You need to look at each aspect
of the print process and determine what you believe to be the most effective in
helping you to achieve consistent results.
This usually starts by measuring and
recording what is being done to help to determine if it is repeatable and if
the results are acceptable. Generally the use of measuring devices such as
spectrophotometers, densitometers, video web inspection, interferometers,
viscometers are necessary to help capture the necessary data in an accurate
form that can then be repeated and measured accurately each time a job is run.
Always try to get your suppliers involved at the earliest stage possible as
they will then be able to assist you in achieving what is best practice for you
and your company and more to the point, how to define it.
September 24, 2012
We seem to always be damaging our anilox. What can we do to reduce this and is there any way of repairing the edges of the anilox without a full replacement?
Considering how long anilox
have been around, you would think that this topic would be long since over but
unfortunately it continues to be the bane of every print shop. I will also
assume that you are referring to laser-engraved ceramic anilox. Damage to
anilox falls into three main categories: Impact, scoring & chipping.
damage is usually caused by the roll surface coming into a hard usually sharp
surface or having a nut, bolt or other foreign object run through the print
Scoring is a little more complex and although it can also be caused by
contamination in the ink such as metal particles and other larger hard objects
it more often comes from running blades dry, running blades out of alignment,
applying too much pressure, running at the wrong angle or simply choosing the
wrong material, thickness or just not changing it soon enough.
generally occurs on the edge of the anilox, which is the most fragile area of
any ceramic anilox. It is critical if a anilox is chipped that it be filled
immediately with an epoxy filler or two part filler such as JB weld as quickly
after the damage has occurred. Although it will never be a permanent fix, it
will slow the rate of break down, and help reduce further damage to the blade and
leakage from the edge of the roll. If you do not repair the chip immediately it
will migrate around the circumference of the entire edge of the roll, making
replacement the only option. One thing many printers do not take into account
is where the ceramic particles go when they chip off the roll, which is
into the ink and how much these ceramic particles actually contribute to
scoring of the roll face so it can have to major visible effects on the anilox
and not just on the edge of the roll. In my experience, if the repair is carried
out speedily and with some care, the repair can hold up for several months or
longer if it is monitored and perhaps even repaired again.