文档介绍：RELATION OF LASER PARAMETERS IN COLOR
MARKING OF STAINLESS STEEL
P. Laakso1, S. Ruotsalainen1, H. Pantsar2, R. Penttilä1
1 VTT, Lappeenranta, Finland
2 Fraunhofer Center for Laser Technology, Plymouth, USA
Abstract
Color marking of stainless steels as a process is known for sometime but still it has not been
used widely in the industry. Some industrial applications have been seen. New MOPA fiber
lasers allow independent tuning different laser parameters and the marking process can be
optimized for producing colors with better quality and visual appearance. Laser processing of
metal surfaces creates an oxide layer on the surface. The thickness of this layer defines how
white light is reflected from the sample. What in principle is only a thin oxide layer on the
surface can be seen as different colors by the viewer. In this study, the visual appearance of
laser marked surfaces was optimized by varying different laser parameters. The aim was to
create a uniform oxide layers on the surface which would appear as a high quality color
marking. Marking quality was evaluated by visual examination. Relation of different laser
parameters to produced color is discussed based on these results. Few application samples are
also presented.
Keywords: laser marking, color, thin film effect
1 Introduction
Color marking of metal surfaces is conventionally done by printing, anodization or emulsion
coating. However, the scratch properties of printing are limited and anodizing more than a
single color precisely is not easy. Emulsion coatings are more expensive and they require one
step more to produce colors. Lasers can be used to create a permanent color mark on a metal
surface as a one step process with a high throughput. Laser color marking of metals has been
used for more than ten years with a variety of different laser sources /1,2,3,4/.
Despite the possibility to vary processing parameters typically in a wide range, some lasers
are more suit