The Impact of Selected Laser-Marking Parameters and Surface Conditions on White Polypropylene Moldings

Abstract

Laser marking of polymer materials is a technology that is increasingly used in industry. Polypropylene (PP) shows a low ability to absorb electromagnetic radiation in the near-infrared range (λ = 1064 nm). The paper presents the influence of the surface condition of white-colored polypropylene moldings on the efficiency of their marking with a laser beam. In addition, the operation of the commercial laser marking additive (LMA) Lifolas M 117009 UN, intended to support the process of laser marking of polyolefin surfaces, was verified. The study is an attempt to combine laser operating parameters, material, and geometric properties of PP moldings to obtain the expected quality of graphic symbols. The test samples were made by injection molding method with the use of a specially designed modular injection mold. The molding cavities were prepared with various methods of metal processing, thanks to which obtained moldings differed in surface condition. The marking effects were assessed based on colorimetric tests and digital image analysis. The 0.5 wt% LMA content resulted in obtaining a graphic sign with high contrast in comparison to the background. The gradual increase in the modifier content resulted in a further increase in contrast. These values depended on the degree of surface finish of the samples, and therefore on the roughness parameters. Samples with a rough surface finish showed higher contrast compared to surfaces with a high surface finish. It was also found that for the analyzed moldings, the laser-marking process should be performed with the use of a low head velocity (450–750 mm/s) and a high concentration of the laser beam (0.03–0.05 mm).

Influence of Laser Marking Parameters in The DMC Code Quality on the PBT/Glass Fibre Composite Surface Using SEM

“…The nature of the laser-material interaction and the quality of the laser marking are highly dependent on both the material composition and the laser settings. Some of the polymers receive additives to facilitate laser marking and improve the quality of the codes, such as PP [13], ABS [14,15], and PA [16]. Some authors have studied the performance of laser marking on the surface of polymeric materials added by nanocomposites.…”

“…Czyzewski et al [13] studied laser marking on PP-LMA surface. They observed that the low value of radiation power can influence the quality of marked codes.…”