Before we use laser cutters, we need to prepare proper files. Following the laser cutting design guidelines is very important. We will talk about that here.
What files can be accepted by laser cutters
To follow the laser cutting design guidelines, we need to know that there are two types of files can be sent to laser cutters, vector file and bitmap.
A bitmap (raster graphics) is an image made up of a rectangular grid cells which are called pixels. Each pixel contains certain color information. A monochrome (black and white) bitmap is the simplest raster image. After the 1-bit image is sent to a laser cutter, the laser will hit the place where there is a dot, and the laser will not hit the place without a dot.
A bitmap file also contains another information-resolution, which indicates how many pixels within a given distance. For example, a 100 dpi (dots per inch) bitmap contains 100 pixels(dots) in one inch (both vertically and horizontally).
Laser cutter needs to know how far apart hit the dots using the resolution information in the bitmap. The best resolution for laser engraving is 100~200 DPI. If it is lower than 100 dpi, you might not get a good fill. And if it is higher than 200 dpi, the laser beam spots will overlap and will take a long time without increasing the quality.
Bitmaps usually are used in the process of laser engraving. There are many different bitmap formats, such as JPEG, PNG, GIF, BMP, TIFF, and more.
Vector files are the most common laser cutting design files that are accepted by the process of laser cutting and Vector etching.
In a vector graphic, 2D points are connected by curves and lines, then these lines and curves form circle, rectangle, polygons, and some other shapes. It uses mathematical formulas to draw these shapes and is not based on pixel patterns. Usually vector images are smaller than bitmap images.
The most advantage of vector files is it is scalable without decrease the quality. When we scale up a bitmap, we will see the individual pixels which make up the image. But when we enlarge a vector graphic, it is redrawn using the mathematical formula, and it will be as smooth as the original graphic. And if you print the vector graphic, you will see it is very clear even though you enlarge it 1000 times.Typically, vector graphics are created in CorelDraw, Adobe Illustrator, Auto CAD, and some other tools. Even you can create or edit vector files with a mobile APP. And you can find many vector files, including SVG, AI, EPS, DWG, DXF, and so on. When you plan to manufacture your parts via an on-demand supplier, you should contact them to know what format file they can accept. And if you cannot get the information, we recommend DXF format files.
How to prepare files – the laser cutting design guidelines
Maximum and Minimum Part Size
Your file cannot exceed the laser cutter’s working area size.
If there is a grid cutting table, you need to ensure parts won’t be lost under the cutting table. Of course, you can still cut small parts, but we don’t recommend.
Try to make any cutouts bigger than the material thickness. Cutouts smaller than that size won’t be accurate and laser cutter might not be able to cut them at all. •
The minimum distance between parts
If you are a laser operator or you are trying to do that by yourself, try to keep the distance between parts when you want to cut more than one part from the same material. And usually it should be about 2x the material thickness.
If you are just a designer, and you don’t operate a laser cutter, we recommend you to send only one drawing of each part. Then you can tell the laser operator how many parts you need. The operator is more familiar with the laser cutter, and he will try to arrange the drawings and keep material to a minimum.
Remove all unnecessary information in laser cutting design files
Before you send your design files to a laser cutter, you must remove all unnecessary information, including comments, notes, borders, gridlines, and other elements that don’t exist on the actual parts.
Connect the design
In your design, all shapes should be connected to the primary material. Sometimes you need to design “bridges” between the primary shape and isolated shapes. Otherwise, the isolated shapes will be lost. If you want an isolated shape to exist on the primary material, you need to consider a “bridge”. For example, when you design texts on your part, such as “a”,” o”, maybe you need to add a “bridge”.
Texts and Logos in laser cutting design
There are two methods to add text or logo on a part, laser engraving and Vector etching.
As a designer, you should decide what you will need and then let the laser operator know that. And you should always prepare vector files of the text or logo; We don’t recommend you to provide raster images to the laser operator, because the laser operator can try to find the best way to do that.
As a laser operator, you need to think about how to achieve the design goals with the laser software.
Remove duplicate lines
Maybe we cannot see duplicate lines, but the laser will. When there are duplicate lines in your file, the line will be cut twice or many times, and that will result in a distorted part edge from the added heat. The cutting time will be longer too. So, try to check your file carefully to ensure there are no duplicate lines.
Laser Kerf and line weight
When we use a router bit or a saw to manufacture a part, some materials will be removed. A laser beam is a cutting tool on a laser cutter. The laser itself has a thickness too, and that is called kerf. So, kerf is the width of the material that is removed by a cutting process. Kerf depends on the material types, material thickness, and some other conditional factors. Usually, it ranges from 0.05 mm to 1 mm. When you plan to assemble laser cut parts and wants them to fit into each other, you must take the kerf into account
If you have the experience to create vector files with software, you will find you can set the line thickness (weight) by yourself. But the laser cutter will ignore this parameter. When designing vector graphics, the line weight must be as small as possible, otherwise, there may be issues when you laser cut the part. AutoCAD = 0.00, Corel Draw = hairline, Adobe Illustrator = 0.001
Make your laser cutting design as simple as possible
The manufacturing costs and time will rise if your design is very complex. You need to make your design as simple as possible-remove intersecting lines, eliminate open shapes, eliminate overlapping lines, and more.
Other laser cutting design rules
On outer or inner corners, it is best to apply a small radius;
For paper-thin materials, try to avoid geometry that has sharply acute angles.
You can get some files and have a try if you have a laser cutter.