Laser marking machine for plastic
In industrial manufacturing, laser is one of the most preferred marking technologies. Metal, plastic, ceramic and other materials can all be marked by the laser in wave length 1064nm (infrared ray), 532nm (green ray) and 355nm (ultraviolet ray). As a high-tech tool, the laser can be appropriate to mark numbers, texts, bar code and matrix code. For example in the figure below, laser marking on plastic bottle, adapter, container seal and ear tags.
The high-speed laser marking machine can shorten the periodic time of the manufacturing process. Meanwhile, the expensive preliminary work and the repairing work of the final stage are not required. Moreover, the laser can be integrated into the automation production line easily. Through the friendly program interface of the users, it can easily switch into the new processing and obtain the products with good repeatability, aging resistance and wear abrasion.
In the application of marking on the plastics, the potential of the laser has not been exerted fully. In addition to the above-mentioned advantages, the increasing marketing of the frequency doubling laser and frequency tripling laser as well as the diversified combination of the material and technology are exploring more new fields for the application of the laser in the plastic industry.
For laser marking on plastics, regulative Q short pulse solid laser marking machine or fiber laser marking machine are the normal types. Their lasers usually have the average power of no more than 100W. Their pulse lasting time is within 10-100ns. The pulse frequency reaches 12kHz. However, in the cases of the fiber laser, it can even reach 1MHz. In such way, the interaction with the material to be marked can be conducted with fine adjustment. The short pulse time will enable the high pulse peak of dozens of kilowatt to reach the average value of 10W.
The laser is the diode pumping laser. It has a high energy efficiency. Because it has very good focusing capacity, it is very appropriate for the refined marking. The diode pumping laser has very high beam quality, so as to make the laser beam to obtain small focusing diameter in the marking process. Therefore, it can realize the precise marking guide width of as small as 30 μm on tiny components.
The laser for marking usually generates the radiation within the scope of the infrared wavelength range. The green laser and UV laser aim at the plastic and semiconductor materials. In the special marking applications, the employment of UV wavelength has initiated the new possibility of using laser in plastic marking. The short wavelength will have direct photochemical reaction with the plastic compound instead of being heated, so as not to damage the material, especially some picky materials, plastics with fire retardant or sensitive electronic components and so on. These lasers will complete the marking with high contrast at a very high speed, without having any negative influence to the surface quality.
The most important is that the plastic must absorb the laser radiation at a high degree. The biomacromolecule structure of the plastics usually absorbs the light in UV and IR ranges (wavelength 10.6 μm). The additive, filler and pigment in engineering plastics have big influence to the absorptive characters of the materials. Therefore, they can't satisfy the high requirements of the laser marking. In order to enable these materials to have durable, high-definition, high-quality marking effects in very short processing time, it is required to deploy the laser sensitive additive. They improve the marking performance of the material at a high degree. Therefore, plastics can absorb the laser beams in the near-infrared range or the visible green laser range. Through this way, a higher marking speed and a better contrast ratio can be obtained.