Headstrikes On UV-Cure Printers 1
Definition A headstrike is any event that causes the printheads or other parts of the carriage to come in contact with the media while printing. Causes Headstrikes usually happen when one or two conditions arise on the printer and/or the media. The first condition is a head height that is too low. Head height is the distance from the media surface to the lowest point of the carriage. On the UV-cure printers, the standard head height is 0.070”.
1. Each jetting orifice is punched through, creating small but very sharp projections. 2. When printing under ordinary circumstances, the jets are 0.085" from the surface of the media. Uncured, Liquid Ink Partially Cured Ink 3. When a headstrike occurs, those sharp orifice projections scrape printed ink and media particles and drive the particles into the orifices themselves. 4.
Intermittent Jets These jets may pass an AutoJet or AutoSet calibration, but when printing begins they drop out. The jets have some small solid particle lodged within the jetting nozzle or orifice. As the particle moves around, it can alternately allow the jet to fire or it can block the jet completely.
Additional Evidence The photographs below are actual prime bar patterns printed by heads that sustained damage in a headstrike. These images are characteristic of printheads that have suffered a headstrike.
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