Holly Steedman of IST INTECH will use her presentation at the IPI Conference in Düsseldorf on 24–25 November to examine the practical challenges of integrating LED curing into direct-to-object inkjet printing.
Printing on a curved surface changes the conditions in which an ink must cure. As the distance and angle between the LED source and the printed surface vary, so can the curing result. A setting that works well on one part of an object may produce a different outcome elsewhere, affecting surface cure, adhesion, gloss consistency and ultimately print durability.
For companies developing direct-to-object inkjet applications, this makes curing an important part of the machine’s overall design. Cylindrical and irregular objects introduce a level of complexity that is less pronounced in wide-format flatbed printing, where the relationship between the light source and the substrate is generally more predictable.
Steedman’s session, “Mind the Gap”, will explore these differences and the decisions involved in building a curing system around a three-dimensional object. The gap between the LED source and the surface is an obvious consideration, but its significance depends on the optical design and the geometry of the application.
Optics determine how light is directed towards the printed surface. Beam angle, focal distance and working distance therefore need to be considered together. As an object rotates or moves through the system, the curing arrangement has to accommodate the changing position and orientation of the areas being exposed.
There is also the question of time. Exposure time, irradiance and delivered dose all influence cure performance, and their relationship becomes particularly important at production speed. Rotation speed and transport speed affect the exposure available, while the shape of the object influences how that exposure is distributed across the surface.
These variables connect curing performance directly to the way the object is handled. They also make it important to consider the ink and substrate as part of the same process. The session will examine how different ink types and substrates affect process stability, and how their requirements relate to the design and operation of the curing system.
Thermal management and shadowing add further practical challenges. Heat has to be managed within the system, while the shape of an object can make some printed areas harder to expose effectively. Those constraints need to be addressed alongside the optical and mechanical design if the process is to deliver a consistent cure at production speeds.
Steedman will draw on real application examples to show how optimising optical design and curing parameters can improve print consistency, reliability and production efficiency in high-speed direct-to-object inkjet printing. For machine builders and printers, the value lies in understanding which aspects of the system to adjust, and how those changes affect the result on the object itself.