An Integrated Laser Marking and Cutting System for Flexible Polymer Printing Plates

Abstract

As of 2020, flexible packaging market is growing rapidly, leading to a demand for technological advancements in the industry. Flexographic relief plates, used to transfer ink onto substrates, are currently cut with a knife-based system. This method is slow, suffers from high tool wear, and cannot cut complex shapes. A laser-based system could offer a solution, but little is known about laser machining these specific types of polymers. This thesis focuses on the development of an integrated laser marking and cutting system for these specific polymers. The research commenced with an investigation into laser processing of polymers, including an optical absorption analysis of the utilised material. With this knowledge, predictions of laser-material interactions were made, to identify the feasibility of available laser sources that for marking and cutting the substrate. Experiments were conducted to evaluate contrast created by chosen lasers during engraving of the material and to determine sufficient cutting parameter. Based on the acquired knowledge, informed decisions were made regarding the design and development of the machine. A 60 W CO2 9.3 μm laser source was chosen to implement into the machine, together with belt drives powered by AV high torque NEMA 34 stepper motors. To steer the beam into the intended direction with 20 mm silicon silver coated mirrors and a 20 mm Zinc Selenide (ZnSe) lens was used. This research demonstrates a new method for cutting and marking flexographic plates, which could contribute to improved automation in the printing industry.