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Marking on Metal

This page shows marking metal. CO2 Lasers of a couple hunderd watts cannot directly engrave metal. However, they can be used to mark metal. Metal that is painted or anodized can easily be marked. In the case of painted metal, the paint is removed and the underlying metal is exposed. For anodized metal, the anodized coating is turned white by the Laser beam and provides a very nice clean marking. Anodized aluminum is a very nice and easy metal to mark.

Bare metal, such as aluminum and steel, or even yellow-chromate or chrome plated metal can be marked with the aid of a chemical. This chemical is referred to as an "Image Contrast Enhancing Agent". An enhancing agent allows CO2 lasers to mark stainless steel, brass, aluminum, bronze, zinc, titanium and others.

Where indicated, two of the items on this page were treated using a contrast enhancing agent for the laser marking of metal substrates. The agent can be applied by a brush or by spraying. The recommended application method is by aerosol can or conventional air powered spray equipment. This provides for a faster application and also a more even coating without brush strokes. The agent is very fast drying. After the enhancing agent is applied to the metal surface, and it has dried, the metal is then marked with the Laser. After marking, the metal is removed from the Laser and the metal is cleaned. Clean-up of the excess agent is necessary after marking has been completed and can be accomplished with water or ethanol.

In this example, we marked three metal pieces

(1). Anodized Aluminum

(2). Yellow-chromate finished Steel

(3). Chrome-plated Steel

The Anodized piece did not require any enhancing agent. Both the Yellow-chromate and the Chrome plated Steel pieces had application of the image contrast enhancing agent.

We used AutoCad to draw an outline of the pieces. We placed a piece of 1/4" cardboard on the Laser table and made a simple cutout of the pieces to be marked. This cutout held the piece at a known location so as to be properly marked. For higher volume marking applications, a similar approach could be used where the entire cutting surface of the Laser has cutouts for many pieces to be processed at one time.

ACAD drawing showing cut outline

AUTOCAD DRAWING:

OUTLINE FOR CUTOUTS IN RED

WORDS TO ENGRAVE IN BLUE

Cardboard jig to hold part

CUTOUT PART HOLDER.

FOR THIS EXAMPLE, CARDBOARD WAS USED

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ANODIZED ALUMINUM PIECE INTO HOLDER

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PART IS HELD AND LOCATED AT A KNOWN POSITION

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MARKING THE ANODIZED METAL

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FINISHED ANODIZED ALUMINUM

ANODIZED METAL ENGRAVES EASILY

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YELLOW-CHROMATE STEEL REQUIRES CONTRAST ENHANCING AGENT

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FOR THIS EXAMPLE, THE AGENT IS BRUSHED ON.

PREFERRED METHOD IS TO SPRAY.

SPRAYING IS QUICKER AND PROVIDES A MORE EVEN APPLICATION

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THE AGENT DRIES QUICKLY AFTER APPLICATION

THE PIECE TO MARK IS THEN PUT INTO THE ENGRAVER

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LASER MARKING OF THE YELLOW-CHROMATE STEEL

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PIECE AFTER ENHANCING AGENT HAS BEEN WASHED OFF

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FINISHED YELLOW-CHROMATE STEEL

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THIS IS CHROME PLATED STEEL BEING MARKED.

THE PIECE HAS THE ENHANCING AGENT APPLIED.

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AFTER MARKING, BEFORE CLEANING

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WASHING OFF ENHANCING AGENT WITH WARM WATER

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FINISHED CHROME-PLATED STEEL

Following is marking Aluminum Stock

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