Laser Marking on White-Coloured Polyoxymethylene (POM) Polymer Substrate: Challenges and Perspectives

Polyoxymethylene (POM) is a semi-crystalline engineering thermoplastic polymer employed in the production of precision parts in applications that demand good dimensional stability and frictional properties. Consistent with modern manufacturing practices, laser marking is a desirable method for marking products for branding and coding in order to enhance traceability and accountability due to its lower costs and amenability to automation. Laser making of transparent and white-coloured polymers is a technological challenge. Laser marking of polyoxymethylene substrate can be quite challenging due to its low laser absorption. In this work, white-coloured POM was laser-marked using a wide range of marking parameters, and a promising range of parameters for laser-marking of white POM substrates was identified. Results indicate that the most promising marking quality is obtained with a laser power of 30 W (100% of equipment laser output) and frequencies in the range of 30 to 80 kHz. Perspectives on improving the quality of the laser marking outputs are presented based on the understanding of the degradation behaviour of POM under the laser marking conditions employed. A new method for improving laser markability of polymers without the need of incorporating marking aids in polymer compositions is demonstrated.