Laser plastic marking technology
Decorative thermoplastic with laser marking took longer to be recognized than expected ten years ago. Nevertheless, laser technology has replaced ink marking technology (such as embossing and inkjet printing) in some applications, and the situation has changed
at present, the so-called "non aesthetic" applications are estimated to account for 90% of plastic laser marking. Some labels are made with carbon dioxide laser machines, including part model, manufacturing date and expiration date. Usually, these marks are black letters and numbers on a transparent or light background, or pure white marks on a black background
"aesthetic" laser marking accounts for 10% of the market and has great development potential in replacing ink technology. This is a typical white mark on black engineering plastics, which is printed with a solid-state nd ∶ YAG laser machine. This laser machine is easy to program and is suitable for making clear marks on products of any shape
the successful commercial applications of laser marking include ABS keyboard for commercial machines, HDPE, PP, pet and PVC rigid containers and container covers; Nylon and PBT automotive and non automotive electrical connectors, hood components such as fuse boxes and gas caps. There are other applications, including TPE ear tags for cattle and pigs, HDPE switch buttons on electrical parts such as cleaning and drying equipment, and PVC pipe fittings such as connectors and pipe fittings
the initial applications include light switch covers, cosmetics packaging materials, car interior buttons and door handles, and instrument panels. In recent years, the latter has become an important application market
in the last decade, the technological progress of computer programmed laser marking equipment has been accompanied by the development of more varieties of laser marking resins. Specially made colorants and packaging additives can be used in a variety of plastics, such as polyolefins, ABS, PVC, polyester, polycarbonate, nylon, polyformaldehyde and thermoplastic elastomers
nowadays, laser marking plastics have high contrast. Sometimes, they are a contrasting color rather than black and white. Even dark contrast is possible. According to Patrick schlather, the marketing manager of rofin baasel, the main supplier of plastic laser equipment, these diverse colors are one of the popular trends, which is causing people to have greater interest in laser decorative plastics
applications of laser marking include light switch covers, cosmetic packaging materials, automotive interior buttons and door handles, and instrument panels. In recent years, the latter has become an important application market, and also meets the development needs of printing a large amount of data on even smaller plastic parts. It also has the functions of low cycle load cycle, deformation cycle and displacement cycle. For example, a two-dimensional bar code with a data density of 10 times that of the traditional bar code has been studied. Compared with the previously used bar codes, printing two-dimensional bar codes requires more accuracy and higher definition. According to schlather, laser marking meets these requirements. Within the range of 0.001 inch, the size and position of points can be repeated - these properties are difficult to achieve by embossing or ink printing machines
environmental problems are another driving force for the development of laser marking. Laser marking does not need ink or solvent, nor does it need high-intensity energy drying process like ink marking technology. Schlather said that for a three shift printing production, ink and chemicals cost $20000 to $40000, while printing plates costs $100000/year or more. In contrast, a three shift laser marking equipment costs less than $3000 in electricity per year, and other consumption such as lamps and filters costs less than $3500
basis of marking equipment
although there are many laser light sources for decorative plastics, sealed carbon dioxide lasers are the most widely used at present, followed by solid-state nd ∶ YAG lasers pumped by lamps and Nd ∶ YAG devices pumped by diodes in recent years
most laser equipment adopts galvanometer marking technology with high-speed beam control. This control device scans the laser beam with a mirror or galvanometer controlled by two computers that can move in the X or Y direction. "When the programmed laser path is completed, the new part is in place and this cycle is repeated. Since the laser mode completely exists in the software, neither the tool nor the mask is needed."
software that allows plastic marking with rotating beam control is also supplied by several laser equipment suppliers. This kind of equipment essentially adopts the same technology, but it is suitable for continuous rotation production, such as conveyor belt or substrate conversion. Barbero explained, "the advantage of this equipment is that it can be easily refitted to the existing production line to maximize the productivity. The coding is fed back to the computer, and the computer makes appropriate adjustments to track the moving target in real time." Schlather continued, "current devices use simple and clear graphics generation software, which is easy to program and print a single data on each and every rotating part."
in recent years, it is easier to program, standardize and troubleshoot laser marking, and the marking speed has also been greatly improved. Barbero said, "today's software is suitable for printing more than 400 words per second, compared with 40 words per second 10 years ago." Most laser machine software has the ability to print serial and multi model bar codes and texts of any model (including the company logo). With the "help" option of window base, laser marking suppliers have added service and standardization technology as well as fault removal software
another development is that two parts can be printed synchronously with a laser light source. Plus a deformation head and a programmed beam splitter, with the same information, a laser machine can print two parts at the same time. Schlather pointed out that this type of equipment can be used for printing large areas or large quantities of products without moving parts
cost is a key factor in the growing popularity of carbon dioxide laser equipment. The price of a complete set of carbon dioxide turnkey equipment is between 25000 and 35000 US dollars, while the price of an electron tube pumped or diode pumped Nd ∶ YAG equipment is between 6000 US dollars. In the era of electronic information and electrical appliances, it is rapidly developing between 0 and 75000 US dollars with the main characteristics of intelligence, cloud, lightness and high speed
the carbon dioxide laser machine etches the plastic surface, and the material is cleaned by evaporation. The contrast mark is obtained, but there is little or no real color change. PVC, ABS and most polyesters are suitable for carbon dioxide laser printing. Commercial resins filled with mica, such as PP, produce frosty gray marks when marked with a carbon dioxide laser. Although the output power of carbon dioxide machine can reach 200W, the most common range for marking plastics is 10 ~ 25W, sometimes 50W
in the coding process of bottled production line, speed is the key, or large letters are required. Generally, carbon dioxide laser machine is used. Steve bone, President and CEO of foba North America laser equipment group, said that the carbon dioxide machine uses the matrix primary mold to print labels twice as fast as the Nd ∶ YAG machine, although it is only a few tenths of a second faster
"nowadays, laser marking plastics have high contrast. Sometimes, it is not so much black and white as a contrasting color, and even dark contrast is possible."
control microsystems' main market focus has always been automotive hood and electronic/electrical parts. Stevenson of the company said that considering a plastic marking, we should first try to print it with a carbon dioxide laser machine. "If you can't get the required contrast or excessive melting, choose YAG laser machine." Heating plastics with solid nd ∶ YAG laser will cause thermochemical reactions (such as foaming) and more color changes. Because the wavelength of the laser produced by this laser machine is short, it can get higher definition. The shorter the wavelength, the less heat is induced by the plastic matrix (cold printing). Bone of foba said that 100 watt nd ∶ YAG equipment for plastic marking is currently popular (due to its high output), but there are also equipment with an output power of 30 ~ 50W. YAG laser machines are generally used for high-quality marking of parts, such as electronic connectors, hood components, lock caps and surgical equipment
schlather of rofin baasel suggested that processors should understand the required production volume and the aesthetic requirements of printing when considering purchasing solid-state laser machines. For example, if you want high contrast, surface has not been measured to interrupt the mark, then high-frequency laser machine performance is the best. However, it depends on whether the low output power of the equipment is suitable for your productivity, although there is a certain degree of decline in gas consumption
there is also a new type of diode, whose power is between 3 ~ 100W. The diode can be used as the light source of the laser machine to replace the electron tube of the electron tube pump equipment. It is said that the structure of diode is 50% more compact than that of electronic tube, and the energy utility is increased by 20% - 30%. The electronic tube equipment needs water cooling, while the diode type needs water cooling or air cooling. The electronic tube generally needs to be replaced every 1000 hours, and the service life of the diode is up to 10000 hours. The disadvantage is that diodes are relatively new and expensive. For example, the diode pump laser machine of foba50w is 10% more expensive than the electronic tube equipment of 100W. However, foba predicts that the price of diode equipment may decline in the next few months, and they will eventually replace electronic tube pump equipment
"environmental problems are another driving force for the development of laser marking. Laser marking does not require ink or solvent, nor does it require a high-intensity energy drying process like ink marking technology."
schrather of rofin baasel summarized the selection of YAG type: "if you want to repair every 600 ~ 800 hours, the investment of electronic tube pump is the least, but you can get the maximum productivity. If you can complete the desired marking with 3 ~ 60W diode pump equipment, the cost of diode pump equipment will be less than that of electronic tube pump equipment within 5 years." Formula for lasers
if you use the right additive formula, foba's bone said that almost any kind of plastic can be marked by any type of laser machine. The supplier of the formula or masterbatch needs to know the resin, the final application, and the type of icon required. For example, some plastics such as high-density polyethylene and polycarbonate can be printed well with YAG laser without any additives in some colors. On the other hand, the carbon dioxide laser machine cannot print these two kinds of plastics well without special additives
the limitation of the existing technology is that the ability to obtain color adjusted laser marking is limited, and the cost of laser optimized plastic is also higher than 10% - 15% of the market price, sometimes higher
bill Blasius, director of the master batch Technology Development Department of Clariant group, admitted that laser marking is limited in pigment selection and color transparency. He said, "we know more about how to use pigments and additives than we did ten years ago. We hope to make full use of chemical reactions when using laser lamps, which occur between special resins and some additives and pigments."
due to the development of compounding technology, we can get almost white marks on black or blue acetaldehyde copolymers, or pure white marks on black ABS. With special formula and laser parameters, we can even get the adjusted color. Schlather explained, "in this way, the etched laser