Many owners of a laser engraving machine will tell you that laser engraving wood has to be the best looking effect that a laser engraving machine can produce.
This is especially true for laser engraving a photo to wood where the grain of the material can have a significantly enhancing effect on the image itself.
All natural timbers and most engineered wooden boards can be laser engraved by a CO2 laser at the 10.6µm wavelength but some natural timbers will not mark with contrast. Therefore, when selecting timber for photo laser engraving it’s wise to consider this point to gain maximum effect.
Timbers that contain a high oil content generally vaporise with a good contrasting effect. Cherry wood and maple would be too of my favourites. These woods also tend to have quite fine grains that enhance but do not interfere too much with the image itself. Oak, for example, is not a favourite of mine because the coarse variations in the look and density of the wood can detract from the effect of the image being marked
Although it is a slow machine, a plotter format laser engraver is best suited where the application requires a mark made over a large area and especially where a high degree of detail is required because the Plano convex lens of the plotter produces the smallest possible focal point, which provides for the highest possible resolution.
Just note however that even when using a lens with the smallest possible focal point, the size of the pulse into wood is far larger than with other materials that vaporise, such as cast acrylic, and certainly a lot larger than materials that do not vaporise, such as laser marking anodised aluminium. This is because the pulse into wood continues to grow in size a little after the pulse has been delivered and also that in order to achieve a good, contrasting effect, most laser engraving to wood has some depth (deeper = lower resolution).
When using a plotter, in terms of resolution it is not beneficial to raster engrave with hatch spacing greater than 0.08mm (300dpi). Higher resolutions can in fact cause the dot pattern to merge and reduce the perceived resolution of the laser engraved photo. Some of the best photo etching to wood work that I have seen has actually been produced with a hatch spacing 0.10mm (250dpi).
Good system software will allow you to adjust the dot pattern of the image at the laser engraving machine itself, however, for machines that do not provide for this, such as those that work via a print driver, it’s important to match the graphical image resolution with the resolution of the machine itself (image resolution in dpi = focal point size and hatch spacing)
Laser engraving photos to wood is quite a slow process and if this is your core business then nothing beats the speed of a galvo laser. Typically, for this process a galvo laser will be somewhere between x3 and x10 (or even faster!) than the speed of a plotter for this application. Therefore, if you plan to grow your business in this field and so long as the image is no larger than 175mm (approx 7”) consider carefully investing in a galvo laser engraving machine because a single galvo system can be an overall much lower cost investment as it can produce at the rate of a whole factory full of plotters and with far lower maintenance issues too.
At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions ideally configured for laser cutting and laser engraving wood. Our experts would be happy to recommend which configuration best suits your application.