In this tutorial, we will show you what you must keep in mind when working with wood and how you can improve processing results.
Since wood is a natural material, the laser user has to consider various characteristics such as density and resin content during processing.
Rule of thumb:
The more uniform the coloring and grain of the wood, the better and more even the laser engraving.
Overview of suitable wood types
|Soft woods||These types of wood, such as balsa wood or poplar, require a lower laser power level and can be engraved and cut faster. Engraving produces less contrast (it is lighter).|
|Hard woods||These types of wood, such as oak or cherry, are examples of dense woods, which require a higher laser power level for cutting and engraving. The engraving itself becomes more contrasting than on soft wood.|
|Coniferous woods||These types of wood, such as larch or fir, are not suitable for laser engraving. They usually have a large number of uneven grains, which are usually very hard. On the other hand, the surrounding wood ("non-graining") is rather soft, which makes it difficult to find the right parameters.|
|Veneers||These are made of real wood and therefore show the same engraving properties as solid wood panels.|
|Plywood||This consists of at least three layers of wood whose grain is glued and pressed at an angle of 90°. Plywood is available in various types of wood and is offered in different thicknesses. The type of glue is important for laser processing, especially during cutting. Choose white-glued plywood panels or plywood panels made specifically for laser processing.|
|MDF (Medium density fiberboard)||MDF is a homogeneous wood-based material made of finely defibrated, mainly bark-free, softwood, which is gently pressed in the longitudinal and transverse directions. The surface and edges are smooth and firm. So MDF can be easily engraved and cut. However, it should be noted that the cutting edges become very dark during laser processing.|
A rule of thumb for laser engraving:
Hard woods result in dark, soft woods in lighter, engravings.
A rule of thumb for laser cutting:
The drier and more resin-free the wood, the brighter the cutting edge.
Determining the engraving parameters
With the grayscale matrix you can quickly and easily determine the desired engraving parameters for yourself.
Tip: The more you defocus (z-offet: approx. 0.5 - 2 mm), the darker the engraving of the wood will be. Defocussing the laser beam increases the laser spot size, decreases the performance density and burns more wood instead of letting it pass directly into the gaseous form. The disadvantage is that details can be lost.
Determining the cutting parameters
You can test the cutting parameters by drawing a rectangle with two differently rounded corners. Send this graphic to the laser. For 3mm thick wood, start with high performance and a cutting speed of 2-5%. Reach your desired cutting quality by gradually reducing the speed.
Laser parameters for download
We have tested the optimum laser parameters for all types of wood from Trotec. You can find them in the JobControl® material database or download them here:
The sticky dust generated by the wood laser should also not stick to the engraving object. Simply glue an application tape onto the working surface. This serves as a short-term surface protection and can be easily engraved along with it. After laser processing, it is simply removed. Application tape is well suited for the engraving of larger areas and for cutting. However, it is not suitable for photo-engraving or very fine engravings, since many small parts have to be removed later. When selecting the application tape, be sure to use PVC-free material and that it is removable.
The right optics
Laser cutting wood is a sublimation process. Precise focusing and the choice of the right optics are therefore crucial. A distinction must be drawn between engraving and/or cutting. While engraving, please pay attention to the following: The finer the details, the shorter the focal length of the lens should be. As a rule, 1.5" or 2.0" lenses are suitable for almost any laser engraving on wood. The situation is different for cutting. The thickness of the material plays an important role here. The thicker the material, the longer the focal length of the lens used. For 1/8 inch thick wood we recommend the use of a 2" lens, for 1/4 inch thick we recommend a 2.5" lens.
The connection of compressed air is recommended especially for cutting wood. A small-diameter nozzle should be used to protect the lens. In addition, the small nozzle diameter directs the compressed air straight into the cutting gap. As a result, dust and gas are removed more quickly and the cutting quality is significantly improved.
Cleaning hardware and optics are important factors in woodworking. Wood dust is extremely sticky due to the resins and oils it contains, and dust tends to settle in the machine. So it is important to clean the machine regularly.
Suitable exhaust system
During laser engraving and laser cutting of wood, dust and gases are produced which must be properly extracted. So the use of a suitable exhaust system is essential.
Relief engraving on wood
Wood is a great material for relief engraving. In a relief engraving, grayscales are converted into different laser power levels, which produces three-dimensional engraving. You can engrave in several passes with relatively high performance, and then perform one or two cleaning passes to remove the smoke residue.
Inlays in wood
Wood inlays (intarsia) are also particularly popular with wood. In an inlay, different woods are laid on a flat surface in such a way that a smooth surface is created, which now contains differently colored and differently structured inlays. Usually the base material is engraved first, and then the material to be laid (usually veneer) is cut and inserted. For the veneer, make sure that the width of the laser beam (cutting gap) is adjusted. This means that the carrier must be slightly larger.