Laser coding on the eggshell using pulsed-laser marking system

Laser coding is one of methods for the identification of production in the food industries. A clear coding should be marked on the package of foods, so the consumers can be aware of the freshness of foods and expire date. Ink printing methods are usually adopted for coding products, but the methods will accompany the problems that the chemical pollution is kept on foods and the signs cannot directly be marked on the surface of foods. Oppositely, laser coding can directly mark characters and figures on the foods. The investigation principally uses the CO2 laser marking system to code on the eggshell. The Arabic number has been successfully marked on the surface of eggshell in this paper. In order to measure the dimension and the quality of the marking results, the scanning electron microscope (SEM) is used to measure the surface and cross-section of the eggshell. The depth of the marking results is approximately fourth of the eggshell thickness. According to the experimental results, the laser coding method does not cause damage to the bottom of the eggshell and the heat affect zone (HAZ) does not influence the egg theca. (c) 2008 Elsevier B.V All rights reserved.