Marking on metal

Traditionally, laser marking involves engraving a physical mark onto a surface, generating a simple colour change in a surface, or etching a surface layer of a material to reveal another, highly contrasting layer underneath.

The non-contact nature of the laser process contributes to low maintenance schedules, as tools do not need to be replaced. Additionally laser marking is also highly repeatable and easily readable - even by machines.

It is, however, also responsible for the production of debris - fine metallic particles removed from the surface as part of the engraving process.

For bearing manufacturers, there are stringent requirements for this process debris. So the marking of bearing housings using a laser has traditionally combined a ‘minimal’ engraving process with an induced change in surface colour.

Until recently, Control Micro Systems of Winter Park, FL, USA, had built marking systems for bearing makers using Nd:YAG lasers, but one of its customers was looking for a way to reduce the cost, maintenance, lifetime and reliability issues associated with the Nd:YAG design.

For this application, CMS engineers pioneered the use of a fibre laser from SPI Lasers of Southampton, UK - more specifically a 100W cw/modulated fibre laser usually used for welding and cutting tasks.

Switching to the new fibre laser meant generating the same thermally induced high contrast mark on the bearing housing, but doing so with less production of debris, with reduced raised recast, and at much greater convenience to the end-user - meaning almost no maintenance, increased lifetime and exceptional reliability.

The small spot size and high beam quality also mean high irradiance at the focus, so the tool equipped with the fibre lasers can produce results faster and at lower power levels. The focused beam consistently treats only a very small area of material, with the benefit that very little heat is generated in the surrounding area.

The 100W fibre laser used in this application typifies the flexibility of fibre lasers as a tool for a wide variety of applications - marking applications are traditionally an application for high energy pulsed lasers, but systems integrators like CMS are redefining these domains.