31 March 2009

Laser Marking Polyethylene Containers

SYNRAD's sealed CO2 lasers are used in a variety of industrial processes including cutting, welding, drilling, and marking.

As a category, plastics are great materials for CO2 laser processing due to their high absorptivity and low thermal conductivity at the 10.6-µm wavelength. In the case of polyethylene, the cutting mechanism is vaporisation, meaning that the material is simply vaporised into a gas by instantaneous absorption of the CO2 energy. Cut edge quality is excellent with no discoloration.

In marking applications, polyethylene provides a nice, slightly contrasting mark due to a marking mechanism called surface melting. In contrast to the typical engraved plastic mark—where material is removed—surface melting causes a change in density and volume at the material surface that causes the mark to become slightly raised. This raised area creates a contrast that is easily seen under most lighting conditions.

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