Laser laser engraving technology slowly into people's daily life, such as the phone back shell pattern, light switch, the car in the control of plastic keys, which the font (pattern) are possible laser laser engraving technology to achieve. Laser laser engraving pattern, the processor may often encounter such a question: "Why laser engraving effect will be uneven?"
The effect of uneven phenomenon may have the following reasons:
The level of the machine is not adjusted well, ie, the vibration lens or the field lens is not parallel to the processing table;
Because they are not horizontal, will lead to the laser beam through the field lens to reach the length of the workpiece on the length of the inconsistency, the final laser falling on the processed object energy will have an inconsistent energy density, then the material will show the effect Inhomogeneous.
Laser output spot is blocked, that is, the laser beam through the galvanometer and field lens flare lack of round enough;
Laser output head, fixtures and galvanometer and so did not tune well, resulting in the laser through the lens when part of the light spot is blocked by the field lens focusing on the frequency multiplier plate presents a non-circular spot, this may also lead to the effect of not Evenly.
There is also a case of galvanometer deflection lens damage, when the laser beam through the lens damage area, can not be well reflected. Therefore, the laser beam is not consistent with the laser energy in the lens damage area and the non-damage area of the lens, and the laser energy acting on the material is not the same, so that the marking effect is not uniform.
Using partial focus marking a certain range of content;
Because each focusing lens (field mirror) has a corresponding range of depth of focus, and the use of off-focus approach will easily lead to a wide range of marking patterns, the edge of the focal point at or beyond the focal depth of focus range, so it is easier Cause the effect of non-uniformity. Therefore, the method of focusing marking should consider the issue of laser energy.
Thermal lens phenomenon;
When the laser through the optical lens (refraction, reflection), the lens heat will produce subtle deformation. This deformation will cause the laser focus to focus, shorter focal length. If the machine is fixed, when the distance is adjusted to the focal point, the laser energy density acting on the material changes due to the thermal lens phenomenon after the laser is turned on for a period of time, so that the marking effect is not uniform. (On the thermal lens phenomenon, refer to the previous article WeChat article).
The reasons for the material, such as inconsistencies in the film thickness of the material surface or changes in physicochemical properties;
Material is more sensitive to laser energy response. Usually under the same material, the laser energy reaches the material damage threshold is certain. When the material coating thickness varies, or there are some other physical and chemical treatment process is not uniform, the same will result in uneven laser marking effect.