Acrylic cutting power and speed with a laser. How is the processing process…

Practice of using a laser with a capacity of 5.5W

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The review is a continuation of the story about the practical application of a laser engraving machine with a working area of ​​A3 format. Last time, it was about a set for independent assembly, component by a laser with a capacity of 2500MW. This time I will talk about its replacement with the declared capacity by 5500MW. From the view, it will be possible to find out how many passages such a laser can burn 3 mm and 4 mm plywood, which is necessary for this and most importantly. then what to do with it. Further. many letters and photos.

So, many probably remember the first part of this review in which I tried to talk about the use of both the machine itself and about working with Benbox software. At the end of the review, I mentioned that the owner of the device had the idea to modernize it and install a more powerful laser.

The main message to modernization was the desire to cut out crafts from plywood. Although initially, before acquiring the first option, there was a need only to cut figures from felt, which, incidentally, the previous laser coped perfectly, it turned out that it also cuts the plywood during the testing period, but this required a relatively long time.

The idea of ​​replacing the air in the air not for a very long time and soon came true in the real order. The laser was purchased here with the DOTGB coupon for 247.99

Supp that it is with a power supply unit.

On the laser case, which is essentially one continuous radiator, there is a sticker indicating the voltage necessary for it and the issued power.

You can use the laser “out of the box”, t.to. The control board is already built and is located above the cooler cooler. To turn on, you just need to connect the power supply. After that, the laser will turn on at maximum power. To turn on the minimum mode is one single button on the board.

Judging by the characteristics, the laser wavelength is 450NM, the color of the beam is blue.

Unfortunately, I, unfortunately, did not take a joint photo of the new laser with the old one, but if in general, then first of all the difference is clearly noticeable in size. Most likely, this is due to the size of the radiator, which looks much larger and more impressive.

In addition, the size of the adjusting part of the focal lens also became about twice as much as.

This is what the laser looks in the prescribed form. It is also seen here that an additional cooler that prevents the settlement of smoke on the laser lenses was still fixed on the carriage and now moves with the laser. Its weight is insignificant and so far it has not negatively affected the operation of step engines.

For fastening, a part of a children’s iron designer was used. With sufficient rigidity, it is quite plastic, so you can easily choose the necessary angle of tilt of the cooler for a specific situation.

Radiators were purchased for installation on two microcircuits of the laser board, t.to. When the device is working, they heat up quite significantly and there were fears for their condition.

The first test tests showed that the laser is really more powerful than the previous one, this is taking into account the same approach to the cutting procedure. That is, oddly enough to state, but “by eye” the power is really increased by about twice.

T.e. The fact that on a laser at 2500MW was cut for 6-8 passes now cut for 3-4. But this is for now (more on that later).

The first sensible craft, at the request of acquaintances, tried to make the so.called “medal”. T.e. it is like a thematic hanger for medals. Since the machine can only be “troika”, they decided to make two blanks and then, gluing them among themselves, achieve the necessary strength.

The photo below shows that the first attempt was not very successful, but all because it is not always clear whether the figure was erased entirely or not, moreover, the bend of plywood that is not always perfectly even affected by this very strongly affects this.

And the fact that the charter is to look for every time what to put the workpiece, so that it was visible from below, how well it was cut out, it was decided to be closing some special adaptation for these purposes.

Based on the features of the design of the machine frame, the use of two long guides seemed an excellent option for this, which did not provide for the movement of the mechanism. In addition, in these guides there is a recess for which you can fix the adaptation.

Cutting speed

Cutting speed directly affects the width and roughness of the cut surface.

There is an optimal value of cutting speed for various thicknesses of the material and the pressure of the cutting gas, which is about 80% of the maximum cutting rate.

Too high speed

If the cutting speed is too high, this can lead to the following consequences.

1) it may not be possible to cut out the material, and the sparks will be dispersed randomly.

2) some areas will be cut, and some. No.

3) the cut area has an inclined strip, and the lower part of the cut is present in the solution.

Too low speed

1) leads to re.melting and uneven cutting surface.

2) the cut width expands, the angle is melted.

Determine the appropriate cutting speed

About whether it is possible to increase or decrease the feed rate, you can judge by the spark during cutting

Рис. 19 Нормальная скорость резания

2) If the sparks are located inclined, the cutting speed is too high.

Рис. 20 Слишком высокая скорость резания

3) if the sparks are not scattered, there are few of them, and they get together, the speed is too low.

Рис. 21 Слишком низкая скорость резания

If the feed speed meets the requirements, then as shown in the figure, the cut surface is a relatively smooth fishing line for a trimmer, and there is no melting on the lower half.

Рис. 22 Нормальная скорость резания

How to do it?

Cutting plexiglass at home is done in several ways. Smarts are used by an electrician, a metal hacksaw, a corner grinder with a three.toothed disk, a nichrome thread. In addition, manufacturers offer special knives for the cutting of plexiglass. Despite many options, laser cutting is the most progressive method. Such equipment allows you to create complex and original contours.

The quality and speed of processing depend on the power of the beam, and the feeding of the sheet affects the gloss edges.

The feed rate depends on the thickness of the material. the thicker it is, the slower the feed and vice versa. The quality of the edge is affected by the verification of the feed speed. With too slow speed, the cut will be dull, with an overly high edge, it will have recesses and the effect of stripes. The exact focus of the laser is of great importance. it should strictly correspond to the middle line of the thickness of the sheet. Organic glass after processing has transparent edges with sharp corners.

The entire process of fllexiglass cutting is under the control of a computer program, the guiding movement of the laser unit. If desired, you can program decorative decoration of the surface of organic glass, engraving, giving it dullness. The material sheet is laid on the work surface, if necessary, it is fixed, although there is no particular need for this, since it is not subjected to mechanical effects.

The necessary changes and tasks are made to the computer program: the number of elements, their shape and size.

A special advantage is that the program itself determines the optimal location of the parts.

After performing the required algorithm, the laser is driven. Many craftsmen independently make laser machines for work at home.

To assemble a laser machine with your own hands, you will need a set of components that allow you to get a quality tool:

• laser gun. for transforming the beam;
• a carriage whose smooth movement will provide the necessary results;
• Many make guides from improvised means, but in any case they should cover the working surface;
• engines, relay, gear belts, bearings;
• software with which it is possible to enter the required data, drawings or patterns;
• electronic power supply responsible for the execution of commands;
• During operation, the emergence of harmful combustion products, whose outflow must be ensured, is inevitable, the ventilation system should be established for this.

The first stage is the preparation and collection of the necessary components, including the necessary drawings at hand. They can be done independently or use the services of the Internet, where there are a lot of useful information and ready drawings. For home use, they often choose an Arduino chip.

The control system can be purchased in finished form or collected on the basis of microcircuits.

Karettes, like many other nodes, can be printed on a 3D printer. Aluminum profiles are used, since they are light and will not weight the structure. When assembling the frame, it is better not to tighten the fasteners tightly, it is most correct to do this after the completion of all stages of work.

After assembling all the nodes of the carriage, the smoothness of its course is checked. Then the corners on the frame to relieve voltage that appeared from possible distortions are weakened, and are tightened again. The smoothness and lack of backlash is checked again.

The next step in the work is the electronic part. A blue laser with a wavelength of 445NM and a capacity of 2 W, complete with a driver, has proven itself well. All wired connections are fought and packaged in a heat shrink. Installation of end circuit breakers provides comfortable operation.

The case for a laser machine can be made of wood-based stove, plywood and so on. If there is no way to make it yourself, you can order in a furniture factory.

How to avoid mistakes?

To avoid errors when cutting organic glass laser, it should be remembered that this method is very different from the mechanical. The laser beam does not cut the plastic. where it is in contact with the surface, the material molecules simply evaporate.

Given this property, the details when cutting should not come into contact with each other, otherwise you can damage the boundaries.

To create a product of any complexity, a model is introduced into the program in vector format. The necessary parameters are set for the temperature and thickness of the beam, if the machine model does not provide for an independent choice of settings. Automation will distribute the position of the elements on one or several sheets of plexiglass. The permissible thickness is 25 mm.

Working with a laser machine requires maximum accuracy during programming, otherwise you can get a high percentage of marriage at the exit.

This will consist in deformation, melting faces or gross sections. In some cases, a polishing mode is used to obtain a mirror cut, this takes twice as long and increases the cost of the product.

Plasma cutting

If the parameters are selected correctly, then in the context of plasma cutting using plasma fusion, plasma clouds appear.

The plasma cloud consists of an ionized pair of metal and ionized gas for cutting.

The plasma cloud absorbs the energy of the CO2-laser and puts it into the workpiece, allowing you to connect more energy with the workpiece, which allows you to melt the metal faster and accelerates the cutting process.

Therefore, the cutting process is also called high.speed plasma sharp.

The plasma cloud is actually transparent for a solid laser, so plasma cutting can only be used for laser cutting CO2.

Gasification cutting

The gas.hazardous cutting evaporates the material and minimizes the thermal effect on the surrounding material.

The use of continuous processing of CO2 laser to evaporate materials with low heat generation and high absorption allows you to achieve the above effects, for example, thin plastic film and non-fluid materials, such as wood, paper and foam.

The ultra.info.impulse laser allows you to use this technique to other materials.

Free electrons in the metal absorb a laser and heat up sharply.

The laser impulse does not react with melted particles and plasma, and the material is sublimate directly, not having time to transfer energy to the surrounding material in the form of heat.

There is no obvious thermal effect in the picosecond impulse ablation, there is no melting and formation of burrs.

Рис.3 Газификационная резка: лазер заставляет материал испаряться и гореть. Давление пара вытягивает шлак из разреза

The laser cutting process is affected by many parameters, some of which depend on the technical characteristics of the laser generator and the laser cutting machine, while others vary.

Advantages of laser cutting

Unlike other methods of cutting, the laser cutting method of organic glass according to the sketch and size of the customer is the fastest, effective and accurate. The main advantages of this technology are:

• process automation;
• high efficiency of work (from 0 to 400 mm/s);
• the reference quality of each processed product, regardless of their quantity and configuration;
• high accuracy of cutting (up to 0.1 mm);
• complete identity of products during circulation;
• perfectly even and clean cut (contour), which does not require additional processing;
• a contactless method of cutting, excluding the possibility of deformation or mechanical damage to the product;
• minimum number of production waste;
• affordable for services (compared to processing material manually).

При условии использования качественного материала (акрила), возможность изготовления бракованного изделия на высокоточных лазерных станках Kamach II 1290 AS и Lestar 1390 практически равна нулю.

Speed ​​and power settings

Speed ​​and power settings are set in accordance with what power the laser tube is installed. Usually, when cutting plexiglass, the settings are the same as when cutting plywood. The quality of the cut product with an increase in the number of passes falls. You should always cut out a plexiglass from one pass. In the second and subsequent passage, the acrylic pair settles on the walls, the roughness of the edge, bubbles occur, this is especially evident on the material from 5 to 10 mm. Settings must be selected on the sample so that there are no problems in the production of finished products. With a short cut of the material, you should either increase the power of the emitter, or reduce the speed of movement.

The process of execution of the order in our workshop takes place in three stages:

In one of the computer programs (AutoCad, Compass, CorelDraw, Adobe Illustrator) a layout is created, according to which contour cutting will be performed.

At this stage, you select a suitable type of acrylic glass based on the properties of the starting material, as well as from the task.

Moving according to a given CNC program, the laser emitter performs artistic cutting, melting a sheet of organic glass.

Features of processing

It is necessary to select processing parameters qualitatively. The quality of the cut depends on how the machine is configured, it can be both matte and glossy, which is very noticeable when cutting out.

The maximum cut.down thickness is determined by the power of the laser tube and the focal length of the lens.

Acrylic cutting parameters on a laser machine: for every 10 power, there is 1.2. 1.5 mm of cut thickness, therefore, if you are faced with an outflow of 10 mm thick, then a laser tube should have a power of 80 watts and a lens with a focal a distance of 2 inches (50.8 mm), but if it is necessary to cut a thickness of 20 mm, then it is already necessary to have a radiation power of more than 130 watts and a 4.inch lens (101.6 mm). Orgeswall less than 10 mm with laser cutting 30. 60 watts. It is also important to understand that the greater the power of the laser tube, the higher the speed of cutting, which directly affects the speed of the production process.

With laser cutting of plexiglass, two types of cutting ends are possible. glossy and matte.

To obtain a glossy end, it is necessary to reduce the supply of air from the compressor. But the compressor should not be completely turned off, since the smoke and dust during cutting should be removed from the focusing lens, otherwise it can be covered with a suspension, it will begin to warm and can crack. If a matte end is required, then it is worth increasing the air supply from the compressor. An increase in the air flow leads to an increase in the speed of cutting.

Cutting speed is usually selected based on the power of the laser tube and the thickness of the sheet. However, it should be borne in mind that too low speed can lead to the fire of the material and its vapors, and too much can lead to a ribbed edge of the cut.

The power of the laser for cutting acrylic varies depending on the thickness. When cutting plexiglass, special accuracy is required. Cut this plastic is easy enough, but it is also easy to damage. The quality of the cut product is dropped with an increase in the number of passes, so it always follows from one pass.

Industries

This method is used for the manufacture of both household and production parts. It has been widely used in different fields: mechanical engineering, medicine, advertising sphere, construction and architecture, furniture production, plumbing equipment, instrumentation, etc.

• In the advertising industry in the manufacture of parts of external and internal advertising;
• In the production of mirrors, gratings, aquariums, decorative interior products;
• In the manufacture of windows, balustrades, glass partitions, pools fences;
• When glazing balconies, windows, production of double.glazed windows and other elements.

The laser performs contour non.contact cutting of different types of plexiglass, and can also process wood, thick paper and other types of materials.

What’s the catch

1000 millimeters. it’s 100 centimeters or 1 meter. That is, the manufacturer assures that the laser on its equipment is able to overcome 1 meter in 1 second, and even have time to draw something sane or cut.

In fact, at such a speed, not one of the existing laser tubes is tralous of the power to carry out high.quality laser engraving or cutting material, even in a straight line.

So you someday carried a hand over the bonfire or flame of the candle, so as not to burn yourself? The speed is about the same.

At such a declared speed, only engraving will be thick, no more than the thickness of the laser beam (up to 0.1 mm), and the depth. Such a cut is very difficult to see, only with a magnifier. And what about the cutting of materials that are thicker than polyethylene, thin fabric or sheet of office paper? over, when moving a laser beam with such a speed of 2 axes, you will slip through steps and the accuracy of its positioning on the desktop will be lost.

Adequately perceive the declared speed of laser cutting and engraving declared by the manufacturer (take the same 1000 mm/s) not in length, but along the total area, that is, in the length and depth of the cut, and the power of the laser tube.

Calculation formula

For example, if you want to apply an engraving with a laser tube of the Reci W2 (90-100 W) or you need cutting 3 millimeters deep along some conditional length, then you must first divide the depth of the cut into the thickness of the beam (3/0.1). It turns out 30. Thus, in order to achieve the necessary result, you will need to go 30 times through the length with the specified maximum speed.

And now we think how much time we need on a cutter of a long laser, for example, 1000 millimeters and 3 millimeters deep (1000 mm / 30 times), it turns out about 33 millimeters per second. And on everything about everything you will spend about 30 seconds.

If your tube is more powerful, for example, Reci W6 (150 W), then you need to divide the power of the tubes into each other (150 W /100 W) and multiply the resulting coefficient by the resulting speed. In our case, it is 33 mm/s (33 x 1.5). It will turn out 49.5 mm/s.

And where is here, please tell me, 1000 mm/s?

But these figures are still indicative, for ideal conditions, without taking into account the amendments to the power of the laser, the flammability of the material, its humidity, the degree of heat dissipation when transmitting energy, the necessary quality of cutting or engraving, and many other unaccounted moments, including the mood of your operator’s operator laser machine.

The main advantages of laser cutting acrylic

The use of a laser for working with acrylic has several advantages:

• Accuracy. When cutting a plexiglass with a laser, the material is not deformed.
• Using a beam with a thickness of 0.1 mm allows you to achieve perfect accuracy. the discrepancy with the specified dimensions does not exceed 0.01 mm.
• The risk of random damage is excluded. This is very convenient for the manufacture of prefabricated structures: parts can be glued immediately after cutting.
• Lack of need for post.cutting. When cutting acrylic with a laser, the ends acquire a polished look already in the process of cutting.
• Economy. Elements can be placed on a heavyweed sheet more compactly than when cutting mechanically, which means that less material goes into waste.
• Solving complex design problems. The laser machine is able to cut out the details of the most unusual and intricate forms from acrylic.
• Volumes. Acrylic laser cutting machines are convenient for the production of a large number of identical details.
• Speed. When cutting and grinding orggers, a laser method is spent much less time than using mechanical methods.
• Price. Laser cutting, especially if only simple parts are needed, will cost the customer very inexpensive.
• The laser beam is suitable not only for cutting, but also for artistic processing of acrylic, for example, engraving.

How to avoid mistakes when working with a laser

Laser’s work is fundamentally different from the operation of mechanical installations. The main feature of the technology of laser cutting acrylic is that the laser does not cut plastic in the literal sense of the word. Where the beam comes into contact with the surface of the material, part of the plastic simply evaporates. That is why it is impossible to place the details when cutting and grinding orgkesh too close to each other. you can damage the neighboring one.

Acrylic glass cutting with a laser is more accurate and economical in comparison with a harsh milling mill or circular saw. All laser machines (they are called ploters) are controlled by a computer.

To create even the most complex product, it is enough to add a layout in the vector format (created in the Corel DRAW program) and set the necessary parameters. the temperature or thickness of the light beam (and some models of the machines themselves choose the necessary settings). Further, the automation will cope itself, optimally distributing the elements on one or several sheets of organic glass with a total thickness of up to 25 mm.

When working with laser ploters, you need to carefully approach the software setup. Incorrectly configured equipment can give a high percentage of marriage: deformed acrylic sheets, melted edges of the product and rude sections.

Some irregularities are also possible when using the machine in normal mode, which is used in the processing of some types of plexiglass, including mirror and colored. Its feature is the supply to the compressed air processing zone. In this mode, the ends of the product do not look polished, but matte. To obtain a perfectly smooth, mirror cut, polishing mode is used. Air is no longer used here, cutting takes twice as much time, and the cost increases.

Tip: Settings of permission

Permission. This is another factor that should be taken into account when you make high.quality engraving. A clear image is important in any gravity work, but the higher the DPI, the longer the product will be engraved. DPI means the ratio of chicks per inch, and the higher the DPI, the closer to each other the points will be engraved. This leads to a highly detailed engraved image, but can take more time than you would like. Having slightly reduced the permission of the engraving, you can increase time savings to 33% or more. To compensate for low resolution, consider the possibility of using various smoothing schemes found in the Epilog Print driver. The smoothing takes visual point patterns that can be seen with lower DPI, and randomizes them, which hides low resolution. Having found the correct combination of the resolution and blurring of the picture, you can achieve a result that will look good and the engraving of which will take less time.

Tip: how to engrave several products at a time

Suppose you have several wooden stands on which you want to engage in your logo. You can place them one at a time in the laser source and engrave them one after another. But was it not better to decompose several at once and apply laser engraving on them?

The trick is to create a grid on which you can lay out the details and accurately apply laser engraving on them. Create a new vector file the size of your laser table. Then measure one of your figures/objects. If you manage to get its exact shape, but if you do not just come up with a beautiful geometric shape, for example, a circle or square, it will definitely fit into it. It will be your target form. Create a target and place your drawing (engraving or cutout) on the target. Now copy the target, your design and insert as many copies as you can fit in the space of your laser table.

Tip: Leave a small space between targets so that they can be put without touching others.

Cut a piece of cardboard in size of your laser table and insert it into the laser. Now make sure that only a layer with targets is chosen for printing. Engrave, mark or cut the desired shapes on a cardboard board. This will create a grid on cardboard, which corresponds to the net in the file. Now place the items that you are going to engrave on the targets marked on cardboard. Do not forget to rethcast the laser to the tops of what you are engraved. Now you can turn off the printing of the target layer and turn on the seal of the design layer.

Until you move the cardboard, you can simply lay out new details, press the engraving and repeat until all the details are ready.