Factors that influence UV curing
Grafica's UV Curing Machine
Type and color of the substrate
There are substrates and colors that absorb UV more than other ones. They make curing slower. Curing may change depending on the grade of the substrates even though they are of the same kind.
Color of the ink (quality of pigment and influence of color-matching) The pigments that absorb more UV make curing slower. The more these pigments are contained, the slower curing becomes. Therefore, there is a limitation to the density and opacity of UV ink. Curing of matched colors may be poorer than each standard color which is used to make these matched colors. Printers must be careful of such matched colors as the mixture of opaque white plus other dark colors like black and blue.
Thickness of ink film
The thinner the ink film is 10-12 microns, the better curing is. Thicker ink film than 15 microns may result in poor adhesion due to insufficient curing. CLEAR INKS cure even if ink film is thicker than 100 microns.
UV power and integral light
There are two ways to measure curing: UV power and integral light, decided by lamp power and the type of the lamp. UV power plus curing time make the integral light. Integral light changes depending on the number of the lamps and curing time with different conveyor speed.
Although general curing efficiency is measured by the integral light, UV power has more effects to the thickness of the ink film stated in 3-d and inner curing. If UV power is not strong enough, inner curing cannot be improved even if the integral light is increased by more curing time. In this case, lower the height of the lamp or strengthen the lamp power.
Temperature of UV dryer and pre-heating
Environmental temperature of UV irradiation gives much influence to curing. The higher the temperature is, the better curing is. For this reason, pre-heating before UV irradiation improves curing, which leads to good adhesion.
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Bhargav Mistry
Technical Problems? Call Me…
DMI's - GLOBAL HELPLINE FOR SCREEN PRINTERS FOR ANY TECHNICAL QUERIES RELATED TO SCREEN PRINTING
dear sir,
is there any calculations in ink or uv curing of the ink so that its easier to follow that specifications for the drier used at particular speed.
thank you
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Generally one should follow with guidelines which the ink manufacturers specifies for their inks on a particular substrates.
The measurement are commonly done using a UV Meter in Milli Joules.
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Cleaning of UV lamps and reflectors will also help good curing.
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Hi Bhargav, extremely impressed with the extent and depth of your knowledge in screen printing, my experience on visit to your institute and further your comments and suggestions are FANTASTIC,i think you can actually push India on the world map for screen printing!
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Thank you Sharatji
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Hi sir, I have been looking into your blog and found it very interesting and informative… currently we’re working on a process where need to photo-initiate a screen printed UV curable adhesive so we can create a pressure sensitive adhesive on the back of a display. the main issue is that we could not found the most suitable parameter for our process.
We have contacted the adhesive manufacturer for help and give us a guideline for our process.
The specific issue that we have is that when I tried to remove the adhesive from the release liner it will pull paint and everything.
Is there a way to perform any adhesion test (I know about 90degree and 180º laboratory tests) but I don’t know if there is another quick process test that can be done so I can correlate my UV curing conveyor settings with an output?
Greetings from Mexico.
Manuel.
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Having assumed as above, the problem is that the monomer component of his adhesive is reacting (actually dissolving) your ink/paint. You should change is ink such that it does not react with the monomer of the adhesive. Suggested inks – Alkyd, Acrylic+Hardener or Epoxy+Hardener. Choice of the ink will be guided by what substrate you are using and adhesion of any of the suggested ink to that substrate.
Hope this helps.
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Namaste Sir,
Can we replace the UV Lamp tube with UV LED ?
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No
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In the existing machine. NO…
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