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How to maintain consistency with curing UV Inks

February 17, 2010 21 comments

My company have sold hundreds of UV Curing system but when ever we get phone call or complaints about curing problems there are couple of thing lacking from the printers side to further invest and the main thing is UV INTEGRATOR to check UV LIGHT INTENSITY. Its like how can you drive a car judging the speed without a speedometer.

Printers buy machines worth millions but hesitate to invest on such petty tools or just neglect for no reason. But they forget that these meters are not luxury but essential tools for maintaining quality and consistency. UV machine only cures the ink and they are featured with an adjustable conveyor speed to set as per the desired value specified by the ink manufacturers in Joules or Milli Joules/cm2.

If you are a quality printer or looking towards upgrading your quality then you need to invest on a good UV INTEGRATOR if you are already using a UV Curing system.

Every ink on different substrate printed with different mesh counts needs different intensity to cure the UV Inks and don’t forget to involve the your ink supplier to give you proper specifications. They have it all ready but you need to ask for it. Even if you get those specifications you need a meter to check on regular basis.

What happens if you over cure the UV inks?
Kindly note that by over curing the surface becomes so hard that when another layer of ink is printed and cured over the first layers, the top layer would experience poor adhesion to the bottom layer. Also over cured ink becomes less flexible and makes the surface hard which is liable to break the ink film during punching or bending.

How to ensure whether my ink is properly cured?
Properly curing the ink film for the first time is very important. Proper cured ink minimizes substrate degradation, over curing, rewetting, and under curing thus optimizes proper ink-to-ink adhesion.

First before starting the production set your conveyor speed as per the meter reading specified by the ink supplier (ensure that the specification matches your lamp wattage i.e. 200/watts/inch or 300/watts/inch) or maintain data as per your last production parameters noted. If you do not have these data or if your ink supplier cannot help you on this then try the following:

First keep your conveyor speed on higher side then usual (kindly note that white and black colors cures slower than other colors and transparent varnishes) then test adhesion by using a cross-hatch tape test (use good quality tapes like 3M Scotch etc.). If you find improper adhesion after the test then reduce the conveyor speed and keep doing it until you find proper adhesion and make sure your substrate do not deform or change from its original shape or dimension. This will lead you cure your UV Inks at the optimum level without under over curing.

Thereafter when you begin the production decrease the speed 20% to 25% from the optimum to adhesion failures.

Also ensure that you clean the mirror polished skin of the reflector regularly. Dirty reflector decreases your curing speed plus over heats the substrates and affect your registration parameters due to the change in substrate dimensions.

So don’t hesitate to invest on a good UV METER. It is not an luxury but necessity to maintain your quality standards.

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