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Useful Tips for the Maintenance of CO2 Laser Lens

For those general output lasers, due to manufacturing process or environment pollution, almost all lenses absorb a larger part of a specific laser wavelength, and thus shorten the life of a lens. The damage to laser lens will affect the use or even shut down the machine.

The increase of absorption for wavelength will cause uneven heating, and refractive index changing with temperature; when laser wave length penetrates or reflex through high absorption lens, the uneven distribution of laser power will increase the temperature of lens center and lower the edge temperature. This phenomenon is called lens effect.

The thermal lensing effect caused by high absorption of lens due to pollution will arise many problems. Such as the irreversible thermal stress of lens substrate, power loss while light beam penetrates lens, partial shift of focus point position, premature damage of coating layer and many other reasons that can damage lens. For lens exposed to the air, while maintaining if not following requirement or precautions, it will cause new pollution or even scratch lens. From years of experience, we should keep in mind that: clean is the most important thing for any kind of optical lens. We should have good habit of cleaning lens carefully so as to reduce or avoid pollution cause by human, such as fingerprint or spittle. As a common sense, while operating optical system with hands, we should wear finger cover or medical gloves. During cleaning process, we should only use the specified materials, such as optical mirror paper, cotton swab or reagent grade ethanol. We may shorten the lifetime or even permanently damage lens if taking short cuts while cleaning, disassembling and installing. So we should keep lens from pollution, such as moisture protection and so on. After confirmation of pollution, we should wash lens with aurilave till there is no any particle on the surface. Don’t blow it with your mouth. Because air from your mouth contains oil, water and other pollutants which will further pollute lens. If there is still particle on the surface after washed by aurilave, we then should use specified cotton swab dipped with laboratory grade acetone or ethanol to wash the surface. Pollution of laser lens will cause serious errors in laser output even the data acquisition system. If we can keep lens clean frequently, that will increase the lifetime of laser.

#Laser Lens #CO2 Laser Lens

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#Laser Crystal #Laser Crystals

#laser crystal #laser welding

Some Useful Detailed Notes on The Laser Welding Technology

Laser welding emerges with the development of science and technology in recent years. What is laser welding? And what are the advantages and disadvantages of laser welding? First, what is laser welding? The world's first laser beam is produced in 1960 by the use of flashbulb stimulating ruby crystalline grain. Limited by the thermal capacity of the grain, the pulsed beams is short and the frequency is very low. Although the instantaneous pulse peak can reach up to 106W, it still belongs to low energy output.

Laser technology adopts the beams of light generated by the reflection of laser from polariscope and congregates the beams in focusing device to generate beams with enormous energy. Once the focus is approaching, the workpiece will be melt or vapored in some milliseconds. This opens up a new welding application domain for high power CO2 and high power YAG laser. The key of laser welding equipment is high power laser, including solid laser and gas laser. Solid laser is the so called Nd:YAG laser. Nd is a rare earth elements and YAG represents Yttrium Aluminum Garnet, with similar crystal structure as ruby. The wavelength of Nd:YAG laser is 1.06μm. It can produce beam transmitted by fiber, so it can simplify beam delivery system, which is suitable in flexible manufacturing systems and remote working as well as high welding precision workpieces. Nd:YAG laser of 3-4 KW output is commonly used in automobile industry. Gas laser is the so-called CO2 laser. Its working medium is molecule gases which can generate iraser of 10.6μm in average. It can work continuously and output very high power; the standard laser power is between 2-5 KW. The Major Traits of Laser Welding Are as Following: 1. The welding is fast and deep with little deformation. 2. It can work in room temperature and disparity conditions with simple equipment and device. For example, the laser beam will not offset; laser welding can be really carried out in vacuum, air or any gas environment, or even through glass or any transparent material. 3. It can weld refractory materials as titanium and quartz and anisotropic materials with good effects. 4. When welding, depth-to-width ratio can reach to 5:1 and the highest can reach up to 10:1. 5. It can applied in microwelding. Slight flare can be generated by focused laser beams which can positioning precisely and be applied in mass automatic production of micro and small workpieces' installation and welding. 6. It is flexible in welding areas that is difficult to access. Especially in recent years, the adoption of optical fiber transmission in YAG laser processing technology has greatly promoted the popularization and application of laser welding technology. 7. Beam split is easy to be realized by time and space and multiple beam can be processed all at once, providing conditions for more precise welding.

However, There Are Some Limits of Laser Welding: 1. It requires high assembly accuracy for weldment and it should has no obvious deviation of beam on workpieces. It is because that the flare is too small and the welding line is too narrow. If the assembly accuracy and beam position cannot meet the requirements, it is easy to make weld defect. 2. The cost and initial investment on laser and the relevant systems are high.

Technological Parameter of Laser Welding (1) Power density Power density is one of the key parameters in laser processing. When the power density is relatively high, the surface would be heated to boiling point in microseconds, thus generate mass vaporization. As a result, high power density is good for material removal processing such as punching, cutting and carving. When the power density is relatively low, it would take some microseconds to meet the boiling point, the bottom can reach the melting point before vaporization occurs, thus a good melt welding is successfully formed. So the power density ranges from 104~106W/cm2 in conductive laser welding. (2) Laser pulse shape Laser pulse shape is an important question in laser welding, especially for foil welding. When high strength laser beam reaches the material surface, 60~98% of the laser energy will be lost by reflection and the reflectivity is changeable by the temperature of the material surface. The reflectivity of mental can vary greatly in a laser pulse period. (3) Laser pulse width Laser pulse width is an important parameter to distinguish material removal and material melting; it is also a key parameter to decide the cost and volume of processing equipment. (4) Influence of defocusing amount on weld quality There are two ways of defocus: positive defocus and negative defocus. It is positive defocus when focal plane is above the workpieces, vise versa. According to geometry optical theory, when positive and negative defocusing plane equals to welding palne, the power densities are almost the same in the corresponding panels, but the actual laser pools have different forms. It can achieve larger depth of fusion when it is negative defocus.

laser welding machine

Application Field of Laser Welding Laser welding has wide application in manufacturing industry, powder metallurgy field, automobile industry, electronics and some other fields.

Volkswagen AG has adopted laser welding in car roof of brands like AudiA6, GolfA4 and Passat. BMW and GM have used laser welding in top of the car frame while Mercedes-Benz has applied laser welding in drive disk assembly.

Except for laser welding, other laser technologies have be applied as well. Companies like Volkswagen GM, Benz and Nissan have used laser to cut covering parts while FIAT and Toyota have adopted laser for coating engine exhaust valve; Volkswagen has used laser for surface hardening on engine camshaft. Domestic vehicle models like Passat, Polo, Touran, Audi, Dongfeng Peugeot and Focus have adopted laser welding technology. Independent automobile brands like Brilliance, Chery and Geely have adopted laser welding as well.

Improvement and development of new laser welding technology Laser welding technology is continuously developing along with the progress of the time. The following three technologies can help expanding laser's application scope and enhancing the automatic control level of laser welding. 1. filler wire laser welding Laser welding generally doesn't fill wires but has high requirement on assembling clearance, which is hard to be guaranteed thus limits the application scope. Filler wire laser welding method has lower requirement on assembling clearance. For example, if the aluminum alloy plate is of 2 mm's thickness, the clearance must be zero for a good shaping. When adopting φ1.6mm welding wire as filler metal, it can form good shape even the clearance is 1.0 mm. Besides, filler wire can be used for adjusting chemical components and multi-layer welding on thick board. 2. Beam rotation laser welding Welding by rolling laser beams can greatly reduce the demands on welding assembly and beam centering. 3. On-line detection and control of laser welding quality It is becoming a hot researching topic on detecting laser welding process by using plasma such as light, sound and electric charge; some researches have achieved closed-loop control.

#Laser Welding

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Laser cutting is a non-contact processing method featured high energy and good controllability of density. Focused laser beam can generate high-energy density flare, which has a lot of characteristics in cutting. There are four ways of cutting to cope with different situations.

#Laser cutting

The Top Four Main Ways of The Laser Cutting

1. Fusion Cutting In laser fusion cutting, the melt material is sprayed out by airflow after the workpiece is melt partly. Material transfer occurs only in liquid condition so this process is called laser fusion cutting. Laser beam and highly pure inert gas together make the melt material leave the kerf; the gas itself doesn't take part in cutting. Laser fusion cutting can achieve higher speed than vaporization cutting. Energy needed for vaporization is usually more than energy for material fusion. In laser fusion cutting, laser beam is partly absorbed. Maximum cutting speed increases along with the increase of laser power and the speed reduces in inverse proportion when the thickness and material melting temperature grow. Under a fixed laser power, the limiting factors are air pressure in kerf and thermal conductivity of material. Laser fusion cutting can make non-oxidation kerf on iron and titanium metals. The laser power density for fusion but not vaporization is 104W/cm2 ~ 105W/cm2 for steel.

2. Vaporization Cutting In the process of vaporization cutting, the material surface reaches to boiling point so fast that it avoids fusion by heat conduction. Some material disappears in the form of vapor and the other is sprayed out by airflow from kerf. It needs extremely high laser power in this situation. In order to prevent material vapor condensation on kerf, the thickness of material should not exceed the diameter of laser beam too much. This kind of processing is only suited for iron-base alloy field. It can not be applied in wood as well as some of the ceramic material, because their vapors will unlikely become condensation in unmelt condition. In addition, they usually have thicker kerfs. In laser vaporization cutting, the optimal beam focusing depends on material thickness and beam quality. Laser power and heat of vaporization have a certain effect on the optimal focusing position. In a certain plate thickness, maximum cutting speed is in inverse proportion to vaporization temperature of material. The required laser power density should more than 108W/cm2, depending on material, cutting depth and beam focusing position. In a certain plate thickness, and if the laser power is sufficient, maximum cutting speed is limited by gas velocity.

3. Controlled Fracture Cutting Controlled fracture cutting is an ultra fast and controllable cutting on fragile material. The main process is: Laser beam heat heats part of fragile material, causing huge heat gradient and big mechanical deformation in the heat affected area, thus leading to crack. As long as keep a balanced heat gradient, crack can be formed in any needed direction.

4. Oxidation Fusion Cutting (Laser Flame Cutting) Inert gases are usually adopted in fusion cutting, if replaced by oxygen or other active gases, the material will be lighted by laser beam and chemical reaction will occur to generate another heat source, making material keep heating, this is so-called oxidation fusion cutting. As to constructional steel of the same thickness, this methods can achieve higher cutting speed than fusion cutting. But the quality of kerf is not as good as fusion cutting. Actually, it can make wider kerf, obvious roughness, increased heat area and worse edge quality. And it has danger of burning sharp corners in the processing of precision model by laser flame cutting. Pulse pattern can be used to restrict the heat effect, since laser power decides the cutting speed. Under a fixed laser power, the limiting factors are oxygen supply and thermal conductivity of material.

The above are the four main methods of laser cutting, which can be selected according to power of laser cutting machine, processing demands and material properties.

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Let We Closely Look At the Laser Cutting Machine

Guide：Invisible light beam has replaced traditional cutting devices in laser cutting machine, which is characterized with high accuracy, speediness, no limit in cutting pattern, material saving, smooth incision and low cost, etc. Laser cutting machine is developing to replace traditional metal cutting equipment. As reported by OFweek Laser: The working process of laser cutting is to transform the emitted laser to high power density laser beam by optics system. The laser beam irradiates workpiece surface and make its temperature to melting point or boiling point; at the same time the coaxial high pressure gas blows the melt metal or gasification away. As the light beam and workpiece move, their relative position forms a kerf, thus complete the cutting. Invisible light beam has replaced traditional cutting devices in laser cutting machine, which is characterized with high accuracy, speediness, no limit in cutting pattern, material saving, smooth incision and low cost, etc. Laser cutting machine is developing to replace traditional metal cutting equipment. As the most popular industrial cutterbar in the 21st century, powerful laser cutting machine has been introduced to various fields gradually and becomes a good helper in manufacturing. What kind of materials can be applied in laser cutting machine? There are metallic materials and nonmetallic materials processing: A: Metal laser cutting machine can be applied in board cutting, punching and carving, including materials like stainless steel, iron, aluminum, copper and other alloy plates. Among them, stainless steel is the easiest to cut, but only for thin ones; it is unable to cut the ones thicker than 4mm. The kerf can be as narrow as 0.1mm, so the cutting has no harm to the material and the kerf is smooth with good perpendicularity. The cutting thickness of carbon steel can reach to 20mm, which is thicker than stainless steel. Because laser has a little heat effect on carbon steel, it has perfect cutting effects. Side trimming quality of high-carbon steel is better than that of low-carbon steel, but the former has larger heat effect area. Most alloy materials can be cut, with corrosion and slag adhesion on a few materials. It is difficult to cut copper by laser. Even if possible, the copper need to be very thin. B: Non Metal Laser Cutting Machine can be applied in materials as cloth, leather, acrylic, plank, paper, rubber, silica gel, EVA, sponge, glass and so on. Compared to mental laser cutting machine, nonmetallic laser cutting machine has more functions and can be used in more different materials. It has no limit on the materials' size and pattern, and the price is relatively lower. The thick plate cutting capacity of domestic laser cutting machine is far behind the overseas high-end equipment. The main reason is the inadequate knowledge about nozzle and air streams. Among the numerous factors that influence the cutting effects, the nozzle's air streams flow field is the most difficult to analyze. Especially for carbon steel, it's cutting needs combustion-supporting oxygen, whose flow field distribution has very obvious influences on the cutting effects. Most overseas laser cutting machine manufacturers have solid technical reserves and a large amount of researches in this aspect, but very little researches in China. When buy a laser cutting machine, buyers should recognize its core configuration which is an important index to measure its performance. The laser cutting machine industry has also been effected by economic crisis, since it is mainly applied in industrial manufacturing. The decline of manufacturing field will directly cut down the amount of sales. Moreover, the domestic laser cutting technology mainly relies on Europe and US and the industrial distribution is uneven - excess capacity in some fields and insufficient inventories in some other fields. More and more factories will go broke and merger and acquisition will occur in succession. Regarding the laser cutting machine processing system, there is still big gap between China and other developed countries. The sales amount is only 2% of the global total amount. In a word, laser cutting processing equipment still belongs to sunrise industry and its profit is higher than traditional industry in general.

#Laser Cutting Machine #laser cutting #Metal laser cutting machine #Non Metal Laser Cutting Machine

The Modern Laser Drilling Machines For the Flexible Printed Circuit Boards

The world has seen a very rapid growth of high-performance handheld gadgets such as smartphones and the tablets, and this has in turn contributed to the fast rise of the electronic industry. Inside these devices are short interconnections of multi-layered Printed Circuit Boards and electrical connections. Flexible Printed Circuit Boards The use of flexible Printed Circuit Boards also known as Flex PCBs provides greater options for production of high-end engraved patterns. These boards are constructed from flexible, high-performance plastic materials that are usually polyimide. This enables the board to bend or flex during the use making them be the best for use on PCB drilling machine. The flex PCB machine is a composition of various materials including the copper foil, glass fiber, and electrical insulation. Laser Drilling Machines for Flexible PCBs There is the emergence of a versatile laser technology that is capable of working with the flexible boards with the use of only one laser source. The flexible laser drilling machines make use of this technology in the drilling, cutting and structuring of the printed circuit boards. The trend towards the production of PCBs has been on the use of boards that have smaller diameters and higher precision with the interlacing of the PCBs on the drilling machine. The flexible laser drilling machines are producing board patterns circuits in a process that make them be even finer with greater precision and pad alignment accuracy. Technologies for Higher Density The demand for PCBs with higher densities has been accompanied by the need for higher precision, smaller diameters, finer liner lines and faster speeds. To achieve all these requirements, the new revolutionary drilling machines make use of the new technologies with high speed and precision using panels and multiple beams and high-speed data processing techniques. Characteristics of the modern Drilling Machines for the Flexible PCBs 1. The Drilling technology PCBs can be divided into single-sided, double-sided or multi-layered boards. This depends on the application and the higher mounting densities that are associated with making the products smaller, flexible and more sophisticated. This makes the diameters be reduce to less than 0.3mm for various devices and smartphones. (a) The High-Speed Spindle The spindle defines the rotating part which holds the drill bit. It is a critical component for smaller diameter drilling. The modern drilling machines are aimed at having higher spindle speed and smaller diameters. To cope with these requirements, the laser drilling machines make use of the air bearings with a direct drill bit that is held by a precision collect chuck that is built into the rotor. (b) Hole Position Accuracy The smaller hole diameters that are needed to increase the density of the PCBs require a very precise positioning of where the holes are to be machined. The modern PCB drilling machines achieve this high precision machining by the use of conventional drill machines that use servo technologies that are able to position in 50ms or less on the circuit boards. Choice of the Laser System for the PCBs When choosing a laser system, it is necessary to make the following considerations. 1. Make sure that the laser system performance meets the demand of the current and future generations of the flexible circuit board. 2. Make sure that the chosen laser technology is capable of handling the selection of materials such as the metal layers, glass fiber, adhesives and the different substrates. 3. Consider the wavelength issues. Consider the absorption rate and the ablation performance of the desired material. 4. Make sure that the performance of the laser including the power, the regulation and the consistency are wide enough to cover a range of the desired material properly. 5. Make sure that the mechanical design of the system delivers the required accuracy. The flexible PCB laser drilling machine consist of optics that are made up of components such as the aperture that is used to control the hole diameter. The lenses are used to select the energy distribution of the laser beam that is generated by the use of the laser head to suit the desired type of the machining. A beam switching mechanism generates multiple beams at higher speed with a consistent pulse energy. The laser demonstrates its superiority over the conventional cutting systems when handling the flexible and very thin substrates with the following benefits. - It is a stress-free operation - There is enhanced processing quality - It is simple and easy to use.

#laser drilling machine #Laser Drilling Machines #pcb drilling machine

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Laser drilling is an automated process that can be used to make drills of alloys and composites that cannot be drilled by the use of the conventional methods. Laser drilling provides the only solution for the toughest and the hardest drilling challenges.

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How the Laser Drilling Machines Working and Effective

Laser an acronym for (Light Amplification by the Stimulated Emission of Radiation) is a technology that makes use of the coherent beam of light in stimulating molecular or electronic transmissions to the lower energy levels resulting in the emission of the photons. This is the core principle behind the working of the laser drilling machines.

The Laser Drilling

The use of laser drilling machine enables nearly all the solid materials ranging from metals to diamonds can be drilled by the use of a suitable laser. Time minute holes that are impossible to create with the use of mechanical processes cab be facilitated by the use of a laser. The drilling is done contact-free with the use of the extreme small optical systems that make drilling be possible at locations where the use of other methods could fail.

The laser beam melts and evaporates the material. This leads to an increase in the material volume in the drill hole leading to the creation of high vapor pressure. The high vapor pressure drives the melt out of the drill hole. In laser drilling, all the laser light is reflected from the rear mirror with 30-50% of the light passing through the front mirror. The laser light continues through the shutter assembly to the angled mirror and down through the focusing length up to the work piece. The laser beam in the laser hole drilling process is coherent with a high energy content. When focused on a surface, the laser light creates the heat that is used for the hole drilling.

Types of Laser Drilling Processes

1. The Single-pulse drilling and percussion drilling

This method is used in the penetration of the drill holes which have a small material thickness, creating a few micrometers of depth. Percussion drilling makes use of the desired drilling depth with the thicker materials by the means of a couple of laser pulses with a low pulse energy and short pulse duration. This results in the creation of holes that are deeper, more precise and with the smaller diameter as compared to the single pulse drilling.

2. Trepanning

Trepanning is a combination of the drilling and cutting process that is used in obtaining larger diameter. The starting hole is created by the use of percussion drilling with the use of several laser pulses. The laser beam the travels over the material in increasing large circular tracks over a certain work piece enlarging the initial hole with the melted material displacing downward from the drill hole.

3. Helical Drilling

Helical drilling is used in the creation of large and deep drill holes of high quality. Using this process, no initial hole is created bit the drilling is done with the use of many large pulses in a circular track into the work piece. Here, the material is displaced upwards and the focus is controlled so that it always remains at the bottom of the hole. When the material has been penetrated, the laser is used to widen the bottom of the drilling and to smoothen the edges.

The benefits of using laser drilling include;

– The processing of high alloy metals without difficulty – Low cost tools that do not wear – Facilitation of the angled drilling of holes even at the most difficult access areas. – There is an economic setup time – It is a non-contact process as there is no tooling wear or breakage with minimal material distortion – Produces high accuracy and consistent results – There is the ability to produce small diameter holes with high aspect ratio – Ease of programming and the adaptability to automation – Increases the production rates with flexible and faster setup times and less tooling

The use of laser drilling machines enhances versatility as the same tool can be used for laser drilling and laser cutting. There is flexibility in the changeovers for the different prototypes used with small batch processing. The machine has the capacity for a higher degree of beam manipulation including the ability to drill shallow angles and shaped holes. The laser machine has the capacity to drill multiple features simultaneously with the ability to process a wide range of materials.

#Laser Drilling Machines #laser drilling #laser drilling machine

UV Laser Cutting Machines in Printed Circuit Boards Manufacturing

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