Laser Marking of Engineering Thermoplastics: The Polyoxymethylene (POM) Case Study

Polyoxymethylene (POM) is a semi-crystalline engineering thermoplastic polymer employed in the manufacturing of precision parts for engineering applications requiring high dimensional stability and good frictional resistance properties. Due to its lower cost and ease of integration into automated manufacturing processes, laser marking is the state of art method vastly employed for marking products aiming to enhance traceability and accountability. Laser marking of polymers can be challenging depending on the outcome of interactions between the material and the laser radiation for a specific wavelength. Low absorption for a wide wavelength range is usual on transparent and white thermoplastics, which is also the case for natural POM. In this work, in a bid to determine the range of feasible process parameters that ensure good-quality markings, which are necessary to developing a lean manufacturing-focused laser marking process, both natural and pigmented POM were laser-marked, and the quality of the substrates and markings were analyzed using a variety of analytical methods. Results indicated a marked difference in the laser mark-ability of natural and pigmented POM, which is attributed to marked differences in laser absorption abilities of natural and pigmented POM.