There are many reasons for wanting to mark metals permanently: part numbers or other identifying marks are important for industrial parts, decorative marking may be applied for creative reasons, metal tags are used to identify larger pieces of machinery.

Several methods exist for etching on metal:

• Stamping, wherein the information is placed on the metal during manufacturing.
• Acid etching, wherein acid is used to burn an image directly into the metal.
• Laser marking, wherein a CO2 laser is used to permanently mark metal using a coating manufactured for the purpose.
• Laser etching, wherein an imaged is directly etched onto certain metals, primarily anodized aluminum

Laser marking and etching are among the most economical and practical ways to permanently mark metal, with unsurpassed detail.

Additional information on metals and metal marking can be found at:

http://metals.about.com/od/publications/Journals_Magazines_News.htm

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