ANALYSIS & OPINION

Imaging simplifies laser marking

Issue: 

Following a Lasys debut, Foba’s Faycal Benayad-Cherif describes how new vision-based mark alignment can eliminate the need for expensive part fixtures when laser marking

Many components in numerous industries are laser marked for traceability or other decorative purposes. Today, in 95 per cent of laser marking applications, parts must be fixed accurately to guarantee proper alignment of the laser mark to the component. Depending on the part complexity, the cost of a fixture can vary from several hundreds to many thousands of dollars. A manufacturing facility that uses a hundred or more fixtures per production site could make substantial savings by being able to remove fixtures.

Imaging technologies are used in the most advanced laser marking systems to enable part validation, pre-mark inspection, automated mark alignment, as well as the post-mark verification of laser markings. The integrated camera prevents marking errors, which is economically significant as parts get marked at the end of the production cycle, when errors can prove particularly expensive.

Common imaging solutions, however, still rely on some sort of low accuracy fixtures to keep the part in the intended position. Other approaches resort to an external camera pointing at an angle toward the laser-marking area to eliminate the motion. Even though fast, this approach introduces optical distortions and significant mark inaccuracies that can limit its use and flexibility, particularly when parts are not flat.

When applying laser marks, fixtures have two key purposes – assisting the operators in presenting the part in the correct position and holding it during the machining operation. Unfortunately, fixtures have a cost, and the more fail-safe they need to be the more complex the design is – and the more expensive they are to produce.

Foba's M3000 laser marking station can be equipped with the new 'Mosaic' software feature.

The challenges get compounded when new products are introduced to the production and each one needs a new jig. Fixtures require documentation, record keeping, proper storage and periodic maintenance, which adds another layer of management. This scenario is common to many industries, such as medical device manufacturing, where Foba has a significant presence.

Foba has developed an imaging solution that uses a concept based on through-the-lens vision combined with image tiling. A miniature camera, embedded inside the laser optics, looks through a set of 10mm galvanometers mirrors to provide multiple high-resolution images, each one 1/30 the size of the laser marking area. By using a tessellation program, called Mosaic, the images are then stitched together to produce a single image that simulates a virtual straight-down view from inside the laser with an imaging field as large as the laser marking area. The straight-down view is critical as it eliminates the perspective inaccuracies of external cameras.

With this advanced feature for automated mark alignment, operators can now place the part anywhere under the laser in any orientation. Within a second the part is imaged, identified, validated and laser aligned – using Mosaic – and then marked with precision. As a result, Mosaic speeds up device handling and laser-marking processes while reducing overhead costs.

The benefits offered by Mosaic are significant cost savings in the design, the manufacturing and the maintenance of industrial fixtures for laser marking. It also offers faster and more consistent production throughput as parts can be marked accurately regardless of their placement under the laser. The ability to run mixed parts on the same conveyor and a reduction of additional hardware for re-orienting and repositioning parts also saves costs. Other advantages include faster reconfiguration of conveyor lines, a reduction or even elimination of fixtures completely, and less maintenance.

Faycal Benayad-Cherif is business manager of software and vision for laser marking specialist Foba

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