Learn about what you need to keep in mind when working with wood and how to improve your processing results.
Because wood is a natural material, the user must think about various characteristics like the density and resin content of the wood when processing.
Rule of thumb: The more consistent the colouring and grain of the wood is, the better and more even that the laser engraving will be.
|Soft woods|| |
Soft woods, like balsa wood or poplar, need a lower laser power level and can be cut and engraved at a quicker speed. These engravings have less contrast and are lighter.
|Hard woods|| |
Dense woods, like oak and cherry, need to be cut and engraved with a higher laser power level. Engravings on hard wood have more contrast than engravings on soft wood.
|Coniferous woods|| |
Coniferous woods, like larch or fir, are not suitable for laser engraving. They typically have a large amount of hard, uneven grains. In addition, the surrounding wood ("non-graining") is very soft, making it hard to figure out the correct settings.
Because these are created from real wood, they therefore have similar engraving properties to solid wood panels.
Plywood is made from at least three layers of wood whose grains are glued and pressed at an angle of 90 degrees. Plywood comes in many kinds of wood and different thicknesses. The kind of glue used is important when it comes to laser processing, particularly during cutting. Select white-glued plywood panels or plywood panels that were made specifically for laser processing.
|MDF (Medium density fiberboard)|| |
A homogenous wood-based material, MDF is made from finely defibrated, mostly bark-free softwood that is lightly pressed both lengthwise and widthwise. The surface and edges are smooth and solid, allowing MDF to easily be cut and engraved. However, please note that the cut edges become extremly dark when laser processed.
A rule of thumb for laser engraving:Hard woods produce dark engravings, soft woods produce light engravings.
A rule of thumb for laser cutting:The drier and more resin-free the wood is, the lighter the cutting edge.
Using the grayscale matrix it's easy to quickly figure out your desired engraving settings.
Tip: The more your lens are defocused (z-offset: approx. 0.5-2mm), the darker that your wood engraving will be. By defocusing the laser beam, the laser spot size enlargens, decreasing the performance density and burning more wood instead of letting it immediately turn into gas. The disadvantage of this is that details can be lost.
Your settings can be tested by drawing a rectangle with two differently rounded corners and sending this image to your laser. For 1/8" thick wood, begin with high power and a speed of 2-5%. Slowly lower the speed to reach your desired cutting quality.
The sticky dust created by laser processing wood should not stick to the engraving object. To prevent this from happening, glue application tape to the working surface. This acts as short term protection and can easily be engraved with it. When the laser processing is over, it can easily be removed. Application tape works particularly well for cutting and engraving larger areas. However, because a large number of small parts need to be removed afterwards, it is not very applicable for photo-engravings and very fine engravings. When choosing which application tape to get, make sure you are getting PVC-free, removable material.
Laser cutting wood is a process of sublimation, therefore precise focusing and the right kind of optics are important. A distinction needs to be made between engraving and cutting. While engraving, please pay attention to the following: The finer the details are, the shorter your lens' focal length must be. Generally, 1.5" or 2" lenses are fitting for just about any wood laser engraving. However, for cutting, the material's thickness must be kept in mind. The thicker the material is, the longer the lens' focal length must be. For 1/8" thick wood we recommend you use a 2" lens. For 1/4" thick we recommend a 2.5" lens.
A connection for compressed air is particularly recommended for cutting wood. A nozzle with a small diameter should be in use to protect the lens. Additionally, the small diameter steers the compressed air directly into the cutting gap. As a result, dust and gas are removed much faster while cutting quality is vastly improved.
When woodworking, it is crucial to clean the hardware and optics involved. Wood dust is extremely sticky because of the resins and oils contained within and dust tends to settle into the machine. For these reasons, it's important that the machine is cleaned regularly.
Relief engraving is fantastic on wood. With relief engraving, grayscales are converted to different laser power levels, creating a three-dimensional engraving. With comparatively high performance, you can engrave in multiple passes and then perform one or two cleaning passes to get rid of any smoke residue.
Especially popular with wood as well are wood inlays (intarsia). For inlays, different woods are laid out on a flat surface in a way that creates a smooth surface containing different coloured and structured inlays. Typically, the base's material will be engraved before the material to be laid (veneer, usually) is cut and inserted. For the veneer, be sure that you change the width of the laser beam (cutting gap). The carrier must be slightly larger.