Basics

Laser cutting is a type of thermal separation process. The laser beam hits the surface of the material and heats it so strongly that it melts or complete- ly vaporizes. Once the laser beam has completely penetrated the material at one point, the actual cutting process begins. The laser system follows the selected geometry and separates the material in the process.

Laser cutting is like any other CNC controlled process but instead of tools it uses a laser beam. There are different kind of laser cutters, the most com- monly used are the CO2 laser which is used for cutting non metallic materials and the fiber laser for cutting metals.

Laser cutting has many advantages. First and foremost the cutting precision is highly accurate because the kerf is barely larger than the laser beam (0.1mm 0.2mm) This allows the machine to cut intricate geometries. Laser cutting produces very little waste if the process was prepared well com- pared to CNC milling. No other technology can cut so many different types of organic and inorganic materials.

What you can cut with a laser: Acrylic/PMMA, i.e. Plexiglas, Rubber, Polyamide (PA), thin <1mm Polycarbonate (PC) Polybutylene terephthalate (PBT), Polyethylene (PE), Polyester (PES), Polyethylene terephthalate (PET), Polyimide (PI), Polyoxymethylene (POM), Polypropylene (PP), Polyphenylene sulfide (PPS), Polystyrene (PS), Polyurethane (PUR), Foam (PVC free), Wood, Paper (white and coloured) Leather, Food, Fabric, Cardboard, Cork, Steel, Stainless Steel, Brass, Copper

What you can’t cut with a laser: Poly vinyl chloride (PVC), thick >1mm Polycarbonate (PC), Acrylonitrile butadiene styrene (ABS), Fiberglass, Coated Carbon Fiber

While cutting with a laser, harmful vapours are discharged by the materials so it is imperative to use an exhaust system. Most of the time this exhaust system should also clean the fumes before releasing it into a chimney. Some materials produce more harmful gases than others so these should not be laser cut at all, for example PVC which emits pure chlorine gas that will damage the machine as well as our lungs.

Process

Laser cutters most commonly use two types of modes, one is vector based and the other is raster based. Most of the time vectors are used for cutting parts and rasters are for engraving.

In a basic CO2 equipment, the carriage focusing on the workpiece surface moves on a bridge that can move in the Y direction. Thus, the bridge moves back and forth, the carriage on the bridge to the right and left, which allows you to reach any point on the work surface. To allow focusing and working with thick pieces of material the table moves in the Z direction.

One of the most important step in laser cutting is to focus the laser beam. This is achieved with different kind of lenses and moving the workpiece on the Z coordinate. This can be done manually or some machines can do it automatically. The laser beam should always be focused on the surface of the material when you would like to engrave it so it will provide the sharpest finish. For cutting it should also be focused on the surface of the material but sometimes when cutting really thick materials it could be focused in the middle of the workpiece. Without focusing the beam it will provide a rough finish, the beam line will be thicker, and it could even burn the material badly or not cut it through at all.

Setting up the laser cut process is done with different kind of programmes, some are specific for machines and some can be used with plugins like corel draw. This is a bit similar to setting up printing for a laser or inkjet printer. you choose modes, place the designs or pictures on the ‘paper’, resize them, etc. The two most important settings here are the speed (mm/s) and the power output percentage of the laser source. To reach the maximum cutting potential of the laser the speed is set very low and the percentage really high. These two options should always be managed together. These options depends on the performance of our machine as well, it will bear a totally different result when using 80% power on a 25W laser or on a 120W laser.

Most of the programmes can manage different colours for vectors and rasters and also set up different processes and options for different colours. With this a complex workflow can be built up with stages like engrave first and cut later.

Vector mode is when the focus car does not scan the area, but only moves along contours. In this case the line thickness of the engraving cannot be any, - it is determined by the applied lens. Of course, it is possible to change the thickness of the line by defocusing, but this changes the thickness in a small margin. The feature of this mode is that the bridge does not take small steps, but, like the head, moves forward backwards to ensure the desired line is tracked. Here, the speed of work can be limited by the intense movement of the massive bridge. This mode is the same as the plotter's long-used drawing mode, but it does not carry a pen here, but focuses a laser beam on the surface. It only depends on the settings that you engrave (scratch) the material in vector mode or cut it completely.

The other mode is engraving or raster mode. When you want to engrave areas that are connected, you use raster work. In this case, the area to be ma- chined is scanned per line by the machine. The bridge is in the first line of work, and the focus trolley on the bridge accelerates the work speed before reaching the area to be machined, traversing the line, slowing down, stopping - while the bridge moves forward with one line - the focus car starts back- wards, accelerates , going through the line, slowing down... and so on. In this case, the system resembles the operation of an inkjet printer, only the bridge does not move over the paper, but the paper is moved under the bridge in that case.

With raster work, you can draw any complex figure - from the shortest letter to the photo. However, this process features some dead time spent on acceleration / deceleration sections beyond the edges of the work area. Of course, the high acceleration achieved by the servo motor drive shortens these sections, but in the case of a large Y-direction, it must be taken into account when calculating the completion time of a job.

Vector and raster mode can also be mixed together, it is possible to engrave a photo than cut it out and so on.

Simple laser cutting in steps drawing the vectors

taking a picture choosing a material importing the workpiece into the preparatory programme (if you use a new material you should make some test cuts on it rst) adjusting the power and speed positioning the material in the machine positioning the laser head on the material so the design will t focusing the laser head starting the smoke exhauster starting the laser cutting

How do you calculate the price for a laser cut job?

Most of the time the price is calculated based on the runtime of the cut process along with the preparatory job. The runtime is based on many factors like the length of the vector, the size of the picture, the dead time while the laser head changes positions or sweep forward and backward, and of course the thickness and material of the piece. Most workshops have a per minute fee for the laser but a lower price doesn’t necessarily means that the overall price will be better. For example if a workshop have a small machine with low maximum power output it will take a lot more time to cut the design than on a bigger machine that maybe have a higher minute fee but a lot faster.

Designing for Laser Cutting - Basic steps

Before you start your design it is imperative to set your default measurement units. Either you design in millimeters or inches you should keep to it for the whole length of the design process.

Some laser cutter programmes are tend to make a difference between outlines or strokes on vectors so if you would like to produce a design for cutting it should be on the lowest setting possible for example in illustrator 0.001pt or in corel draw hairline. If you forget this step it is possible that you get an engraved surface at the end or the kerf will be a lot thicker than it supposed to be.

One of the biggest possible problem with a vector graphic is double lines or triple lines even. Double lines are really hard to spot because they are perfectly placed on top of each other and if a design is built up from a lot of vectors it is hard to spot them manually, some algorithms can spot and delete them but not every time. The laser cutter will go through twice or more on these vectors so it will possibly burn the material and double the cutting time thus double the price of the job as well. Some design programmes like AutoCAD or ArchiCAD are tend to produce this problem so if it is possible you should check your design in a different programme before sending it to the production team.

Another problem could be open vectors and small gaps in the design. If you provide open vectors for the workshop, it is possible they won’t join them and the laser will not keep to a simple path but will jump around on the individual vectors in sequence as the vectors appeared in the vector graphic. This will raise the cutting time thus raising the price of the job as well. If small gaps remain in the file, the laser won’t cut it through there so at the end you need to break out the parts from the material. This could happen on purpose as well if you work with small pieces and are afraid they will fall out and vanish in the machine. These are called microtabs.

If you would like to produce a lot of parts you should also think about arranging your objects on your material. If it is possible it is a good idea to arrange the objects so they will share lines. There won't be any waste material between them and the cutting time will be reduced. Watch out for double lines here! If it is not possible to arrange the objects so they share lines you should keep them away from each other so the laser beam won’t accidentally cut into one of the objects while cutting the other out, 1 millimeter should be enough most of the times.

If you’re cutting type out of your design, like a stencil, be sure to use a font with stencil properties, or be sure to manually create

If its possible designs should be bigger than 6mm/0.2

Designing for laser cutting with Illustrator

Illustrator FAQ

What color mode should Illustrator be in? Designs need to be in RGB color mode. Go to File > Document color mode and make sure your document is set to RGB - then create your design.

How do you convert fonts for laser cutting? Any text you use in your design file needs to be converted to paths. This way the laser cutter will follow your design correctly, regardless of whether or not it has the font installed. This is as simple as selecting your text and then choosing Type > Create Outlines from the top menu. You won't be able to edit the text once you've done this, so do it last after your spell check. You can engrave text into the materials using area engraving, line engraving, or a combination of both.

How do you convert images for laser cutting? Our making system only registers vector artwork. It will ignore images inserted into your design in other formats (such as .jpg or .bmp). You can trace the image by selecting the inserted image and using the Object > Live Trace > Tracing Options command. Then choose 'Black and White' with the 'Ignore white' option checked. Adjust the 'Threshold' slider to adjust how the image is traced. Next, you'll need to use the Object > Expand command. If the trace has worked correctly, vectors should appear around all of the individual parts of the traced image. You'll be able to edit the vector paths as you wish.

OK let’s start with the basics.

Open illustrator and create a new document. As mentioned before it is a good idea to create an artboard the size of your material so there won't be any problems later on with sizing.

Illustrator have many tools some basic and some advanced. For a simple project basic tools are perfect. If you would like to create basic geometric formes illustrator can do it for you. These will be created as vectores, perfect for laser cutting, or even engraving.

You can create simple straight lines with the line segment tool.

For basic geometric shapes you can use the shape tool group. Here you can create easily a variety of shapes like rectangles ellipses and so on.

If you would like to keep your shapes regular hold down the SHIFT key while drawing it.

It’s also possible to select a tool and than click on the art board, this way you can give a precise size for the geometrie.

If you would like to draw a polygon you can use the polygon tool in the shape group. You can change the number of sides for the polygon with clicking on the work area.

The next one is the pen tool. This is a bit more advanced but with a little practise it could be perfected. With the pen tool you can draw any segmented shape. The tool adds anchor points to the work area which are connected with a straight line. You can add and delet anchor points later on if you would like to change the spae of the line. If you would like to close a shape you need to click on an existing anchor point. If you would like to finish a line with- out closing the shape press enter.

If you would like to freeform arcs or curves you can use the curvature tool. This is similar to the pen tool, you can place add or delete anchors similarly. In older illustrators these two tools are often the same. With this tool while you place the next anchor point you can control the curvature of the line as well. If you want to adjust the curvature later you can doing it by selecting the direct selection tool than clicking on one of the anchor points and pulling the little handles.

With the selection tool you can do a variety of actions. Like resizing the object, first select the object you want to work with, you can see a blue selec- tion bracket appears and by pulling the corners of the selection you can resize the object. if you would like to keep the ratio of the object while pulling the corners keep SHIFT pressed otherwise it will get deformed.

If you right click on the object with the selection tool you can access a more varied selection of transformation tools.

Now you have a basic knowledge of the simple tools illustrator provides you for vector creation. Let’s look at the basic setup for laser cutting.

There are two modes: cutting and etching, this can be controlled with the fill and stroke tool. For most laser cutters if you would like to cut the material you need to set the stroke of the vector to the thinnest weight possible, in illustrator this is 0.001 pt. Anything thicker than this will probably be etched, also any filled area will be etched as well.

To export your file go to the file menu select export than export as and choose your output. The most common file outputs used by laser cutters are DXF DWG PDF AI CDR. But a workshop may ask for a different file extension.

Lines must form a closed contour. Otherwise your part may stuck into the material and needs to be cut out manually.

Please try to avoid overlapping lines. The cutting software will recognise them and calculate them as extra cuts thus increasing the overall price.

The scale must be 1:1. You can check if the dimensions are correct after uploading your design.

If you prepared a typo please make outlines from it. This way if the workshop don't have your fonts it won't be a problem.

If you prepared a typo please keep in mind that the insides of the letters will fall out. If you want to keep them together you need to connect them to the part.

If you have multiple parts please arrange them at least 1mm from each other. This applies if working with non metallic materials. If you work with metallic materials the distance should be as large as the material thickness.

There must be nothing else in the cutting file besides the cutting lines. No title block, dimensions, tolerances, centre lines, bending lines or hatching. Any specifications should be in a separate file and uploaded separately.

If you work with splines please convert them to arcs and lines. The software of laser cutters often have problems with splines creating misshappen forms.