The digital revolution has its sights on a new challenge, and decorating three-dimensional objects offers no shortage of puzzles or possibilities.
By Debbie Thorp
Inkjet inks (typically UV LED-curable) must adhere to a wide range of substrates including glass, metal, and a multitude of plastics. Different substrates require different pretreatment processes such as alcohol, flame, plasma, corona, or coating primers. Post-print varnishes and protective top coatings may also be needed. System developers are beginning to incorporate these processes. For example, the Xjet from Inkcups Now offers the DigiBond Primer for printing onto metal; Apex Machine provides an optional inline pretreatment station for their DB1000 and DRT2000 Digital systems; and Engineered Printing Solutions (EPS) offers pretreatment and vision system options for its XD070 and XD060 systems.
Courtesy of Inkcups Now.
Certain substrates benefit from a base coat of white ink to make the overprinted colors brighter, but matching the opacity of a screen printed white is a challenge for inkjet. Multiple printheads or passes may be needed to jet an acceptable layer of ink. Many system vendors now offer an optional white ink station; in larger production systems, white is standard. However, an alternative to using inkjet for the white base coat is to take a hybrid approach and combine the strength of screen and inkjet technologies in a single line. This has been shown by KBA-Kammann in its latest K20 series. The company has taken the approach that the inkjet stations must fit within the system architecture of its K20/K15 series screen printers, with no loss of speed – so that, according to job requirements, users can produce hybrid technology decorated products. For example, they could use the screen stations for the white precoat and spot colors and inkjet to print CMYK.
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