Types of Metal
Cermark and Thermark Metal Marking Compound
Powder Coated Metal
All materials have unique characteristics that dictate how the laser beam interacts and consequently modifies the material. The most common processes for metals are the following:
Laser Cutting of Metals
The energy of a Fiber laser beam is easily absorbed by most metals, causing the material directly in the path of the laser beam to rapidly heat up and melt. If the laser power is sufficiently high, the laser beam will melt completely through the material. A jet of high pressure air is used to remove the metal as it melts, resulting in smooth and straight edges with minimal heat affected zone.
Laser Engraving of Metals
The power of the Fiber laser beam can be limited so that it removes (engraves) material to a specified depth. Several laser engraving passes are usually required. The common depth for metal laser engraving is 0.003 to 0.005” (75 to 125 microns). However removing this much metal in a single pass could cause melting or distortion. Therefore metal engraving is usually done in multiple passes. The laser engraving process can be used to create permanent identification marks that can’t be removed by heat or wear.
Laser Marking of Metals
Laser marking changes the appearance of the metal surface without removing material. There are several different types of laser marking that can be used for metals. Direct laser marking can be done with either a Fiber laser or a CO2 laser. In direct marking, the laser beam energy heats the metal surface causing it to oxidize. This oxidation causes the metal that has been exposed to the laser beam to darken, creating an indelible, black mark. The Fiber laser can also be used to create a bright, or polished, mark on the metal surface. Metal can also be marked indirectly, either by adding a coating such as metal marking compound, or by removing a coating such as paint. Laser marking can be used to convey information such a serial number or a logo.
The laser cutting, engraving, and marking processes described above can be combined without having to move or re-fixture the metal part.