No doubt, if you have researched UV inkjet digital printing, you have learned a little about pinning. Pinning is a dose of LED curing that sort of freezes the UV inkjet droplets in place on the web so they can travel through to a final cure at the end of the press prior to re-rolling or die-cutting. Pretty standard as part of the UV inkjet printing process.
Wikipedia describes pinning as “the process of applying a dose of low-intensity UV light to UV curable ink. The light’s wavelengths must be correctly matched to the ink’s photochemical properties. As a result, the ink droplets move to a higher viscosity state but stop short of full cure”
There are different press configurations that Pin after a group of colors and after a white, etc. or the configuration where Pinning is done after each color. This is an important factor in deciding which digital equipment best fits your needs.
- Dot gain
- Line spread
- Ink to substrate interaction
- Ink to ink interaction
In many cases pinning after the white and then pinning after the CMYK is adequate and produces great quality and durability etc. However, You may want to consider equipment that pins after every color if you want to use your press with more porous substrates or if you are looking to control the ink spread for a bit tighter dot. Inter-color pinning is beneficial to print quality as it provides a better ink laydown and improved dot shape with virtually no ink spread.
Pinning is a critical function of UV inkjet printing and can impact overall quality. UV inkjet technology depends on the exact placement of the ink droplets, and managing how they perform and react to substrates at speed will make a difference.