Caused by industrialization is escalating, the processing requirements of industrial products are getting higher and higher, and the customization is becoming more and more extensive. Laser engraving and cutting technologies have been developed by leaps and bounds. The laser has high energy density, strong operability, a wide range of processing materials, smooth cutting edges, no burrs, no polishing, no noise, no dust, fast processing speed, high precision, less waste, and high efficiency. It becomes a good solution for all industries, Especially in revolution and replacement. Laser engraving machine can be roughly divided into non-metal laser engraving machine and metal laser engraving machine. Non-metal engraving machine can be divided into CO2 glass tube laser engraving machine and metal radio frequency(RF) tube laser engraving machine. Metal engraving machines can be divided into metal fiber marking machines and metal fiber laser cutting machines. In order to choose the right laser machine, this article will explain the non-metal laser engraving machine and elaborate on the following aspects:
Affecting Factors on non-metal laser engraving
The 4 most fundamental elements of laser engraving: engraving speed, laser power, engraving accuracy, and material.
To achieve a certain engraving effect on a specific material, a laser with certain energy is required. This energy can be understood as the absorbed laser energy = laser power/engraving speed. In brief, to increase the absorbed laser energy, you have to increase the laser power or reduce the engraving speed. Which factor is needed depends on the material and the final engraving performance.
Generally speaking, users will avoid reducing speed, because that will reduce production efficiency. In fact, it is not only the speed that affects the efficiency of engraving but also the accuracy that has a great influence on it.
Engraving materials
Wood
Wood is the most commonly used laser engraving/cutting material. wood is easy to engrave and cut. Light-colored wood such as birch, cherry, or maple can be gasified by laser well, so it is more suitable for engraving. Each kind of wood has different characteristics, some are denser, such as hardwood, which requires greater laser power when engraving or cutting.
The depth of wood cutting by laser engraving machine is light approximately 5mm. Caused by the power of the laser is small. If the cutting speed is slow, the wood will burn. If you want to solve this issue, you can try to use large-size lenses, and repeated cutting. After the engraving, there will be burn marks. It has a primitive artistic beauty that matches the wood background color. The depth of the color mainly depends on the laser power and the engraving speed. If you have special requirements for the color of your works, you can use acrylic to paint for it.
MDF
MDF with thin wood grain on the surface. The CO2 laser can engrave on this kind of material, but the color of the engraved pattern is uneven and black, you have to paint. Under normal circumstances, you can learn the appropriate design and use 0.5mm two-color plates for the inlay to get better works. When engraving, the color of the graphics can be set to 60% grayscale to make the bottom surface of the engraving have some pitting to improve the adhesion of the color. After engraving, you can use a duster to clean the surface of the MDF.
Acrylic
Acrylic is commonly used engraving material. It is easy to cut and engrave. There are various shapes and sizes, and low cost relatively. Acrylic has two production processes: casting and calendering. Laser engraving is mainly produced by casting, because the frosting effect produced by laser engraving is very white, which is in sharp contrast with the original transparent texture. The acrylic produced by calendering It is still transparent after laser engraving, without a sufficient contrast effect. When you are purchasing, you need to emphasize the high-purity cast acrylic with the dealer, otherwise, the material may melt during engraving or cutting.
Regularly, acrylic is engraved from the back, which means that it is carved from the front and viewed from the back, which looks more three-dimensional. When engraving the back, please mirror the graphics firstly, and the engraving speed should be fast and the power should be small. During engraving, if the power is too high uneven stripes will appear on the bottom surface. If you want to engrave deeper, try to repeat the engraving. Acrylic is easy to cut. If the customer’s requirements are not ultra, it can be delivered after cutting without any polishing. In addition, a blowing device should be used for cutting to improve quality performance. When acrylic more than 8mm thickness, you have to use the large power laser tube will be better (Note: The operator must not leave when cutting acrylic, there may be flames during cutting.)
ABS plate
ABS plate is a kind of plastic specially used for engraving, which is composed of two or more layers of colors. American ROWMARK is recognized as the best product for its stable quality and complete variety. The regular size is 600X1200mm.ABS plates are used for various indication signs and badges, which have the characteristics of uniform color, clear patterns, and durability. ABS plates can be divided into two categories: mechanical and laser. Some of the mechanical plates can also be used for laser engraving. The characteristic of a laser engraving board is that the surface color layer is thin (<0.1mm), and the whole board is thinner than the mechanical board (laser board is generally 1.3mm&0.8mm, the mechanical board is generally 1.5mm). The laser engraving effect will be very good, with obvious contrast and clear edges. When using a mechanical board with a thinner surface, the engraving effect is not much different from that of a laser board. If you look closely, the edges may not be as clear as the laser board. When cutting the ABS plate, pay attention to the speed not to be too slow. Do not cut through at one time, just divide it into three or four times, so that the edge of the cut material is flat and there are no melting marks. When engraving, the power should be suitable, not too big to avoid melting marks. After engraving, you can use a duster or alcohol to clean the surface.
Glass
The laser can engrave on the glass surface, but the engraving depth is not deep and cannot be cut. The engraving of glass is usually difficult to control. Follow the steps below to make a smooth frosted surface: paint a little on the area to be engraved and wash it off, cut out a piece of newspaper or napkin that is slightly larger than the area to be engraved, and use water. Soak the paper completely and squeeze out the excess water. Put the wet paper on the area to be carved and spread it out without creases. Put the glass in the engraving machine, engrave the paper when the paper is still wet, then take out the glass, remove the remaining paper, and then clean the glass surface. The laser power smaller, the precision set at 300dpi, and the engraving speed faster. when you engraving the bottler or cup you’d better connect a chuck rotary.
Carton
The corrugated carton packaging printing plates gradually apply laser engraving technology. In fact, corrugated box packaging is divided into two categories, one is sales packaging, and the other is transportation packaging. Automatic laser engraving and plate making can achieve 40-60 line printing effect, and manual plate making is below 40 lines. Laser engraving completely replaces manual engraving. Due to the low cost of laser engraving and plate making, only a quarter of the cost of resin plates. At present, the carton industry generally uses laser engraving and resin plates as corrugated box packaging printing plates.
Five factors of non-metal laser engraving machine selection
Working table
When you choose the model and power of their own engraving machine take your business requests and budget into consideration. Generally, small-format engraving machines are 300m×200mm, 600mm×400mm, and 600*900mm. Engraving ABS, Acrylic is the most basic application of small-format engraving machine, and it is acceptable. When engraving a large plate, there will be some unnecessary leftover materials. The large-format engraving machines are 1300mm×900mm, 1300mm×2500mm, the working table will be bigger enough. Nowadays the acrylic and ABS, PVC plates are basically 1300mm×2400mm, so these machines are more suitable for you who need large-format engraving machines.
Laser tube
When choosing a laser engraving machine, select the appropriate laser tube according to the material of the engraving. For example, a 60w laser engraving machine can cut 8-10mm acrylic, and an 80w laser engraving machine can cut 8-15mm acrylic. The laser tube is the heart of the laser engraving machine. There are some reliable brands such as reci, efr, etc.
Regarding the laser tube, We will write a special topic to help users have a more comprehensive understanding next time.
Co2 laser lens
The laser lens is related to the accuracy of engraving and cutting. It is an important part of achieving the performance of engraving and cutting. In theory, the smaller the focusing spot the better working performance, so that the thinner the laser beam, the higher the engraving quality. Co2 laser lens can be divided by raw materials:zinc selenide and gallium arsenide lenses.The difference is as follows:
| Material | Thermal expansion rate | Rate of change of refractive index to temperature | Thermal conductivity | Refractive index |
| ZnSe | dh/dT=hx8.5x 10-6/k | dn/dT = 64×10-6k. | 0.18W/(cm.k) | 2.4 |
| GaAs | dh/dT=hx5.7x 10-6/k | dn/dT=149×10-6k | 0.48W/(cm.K) | 3.27 |
For the different application scenarios of the two types, please pay attention to the update of our follow-up articles.
Zinc selenide is divided into imported materials and domestic materials. The English abbreviations are PVD and CVD. We will elaborate on specific comparisons in future articles. There is a big price gap between the two types, and the working performance and service life are also very different. You can consult the manufacturer before buying. Internationally renowned lens supplier brands such as II-VI, Ronar-smith, Ophir.
Weight of machine
In order to reduce costs, some manufacturers use very thin iron sheets to make the machine body. Over time, the frame will be deformed, which will affect the engraving accuracy of the laser engraving machine. A high-quality laser engraving machine should adopt a frame structure and weld with high-quality steel. The casing is made of high-quality cold-rolled steel plates. Before ordering the machine, we can see whether the frame structure and the thickness and strength of the casing iron sheet are used to inspect the quality.
Accessories
In order to ensure better working conditions, water chiller, exhaust fan, Chuck rotary, and fume extractor are required as auxiliary equipment.
Water chiller
Electric energy is converted into laser, and its photoelectric conversion efficiency is about 3%, and the remaining electric energy is converted into heat energy. Thermal energy has great destructive power on laser devices, causing YAG laser crystals and xenon lamps to rupture, deformation of the condenser cavity, etc., so there must be a cooling system to provide cooling protection.
Exhaust fan
The main function of the exhaust fan is to remove the dust and smoke generated by cutting and improve the air quality and visibility of the cutting pieces. The regular model is 550w power.
Fume extractor
When the laser machine is working, there is a lot of smoke and exhaust gas will be generated, especially when the processing materials are leather, leather, and PVC materials, the smoke and exhaust gas have an unpleasant smell, which seriously affects the working environment. The soot purifier is specially designed for the purification of soot caused by laser engraving and marking. The pre-filter layer can absorb relatively large particles in the airflow to prevent the main filter layer from being blocked prematurely; the main filter layer is filtered by HEPA The HEPA high-efficiency filter element has a filtration efficiency of 99.99% for 0.3-micron particles. The gas filter layer is composed of a chemical filter element, which can effectively remove harmful gases in the airflow. If the budget is sufficient, it can be used as an option.
Rotary Axis
The main function of the rotary axis:
1. Calculate the rotating engraving path without expanding the surface;
2. There is no need to rotate the workpiece repeatedly; the tool path calculation is completed at one time.
3. Reduce the finishing allowance; the tool path can be roughed in layers.
4. Realize partial rotation processing; the angle range and long range can be set.
5. Affected by the accuracy of the fixture, the machining of irregularly rotating workpieces usually adopts multi-face rotation positioning machining. There are always seams between different machining directions.
6. There is no positioning joint. The rotary engraving process adopts the integral method of the rotating shaft, and the engraving machine generates an automatically closed rotary engraving processing path
The mainstream in the market is a simple rotation and chuck rotation. You can consult the machine supplier in detail during the purchase process.
All of the above opinions are not for commercial purposes. Any errors, we’d happy to revise it.
