What to Consider
To start with, laser engraving is a modern but simple technique used to make permanent marks on various materials. Over the years, this technique has proven to be of great importance to many industries as it brought about various designs and innovations. However, wood is one of the preferred materials to be engraved on due to its availability and versatility. Moreover, with a laser wood engraver in your hands, the possibilities are endless.
Engraving wood has a similar process to other materials like acrylic, textiles, and leather, although it has some specificity. A laser beam passes over the wood, which heats up and vaporizes in a sublimation process. This results in a smooth, precise, and perfect engraving that cannot be duplicated by other engraving approaches like CNC machining and saw-based techniques.
Factors that could affect the outcome of wood engraving
Wood is a natural material and therefore has a lot of inconsistencies associated with its engraving. However, once one gets the nitty-gritty of these things, such as type of wood, power settings, and speed, a perfect engraving is achieved. Also, the type and quality of the machine used is a huge factor to consider in this case. The types could vary based on the power rating, engraving area, and the use of diode or CO2 for the actual engraving. Some other important factors to be considered before starting your laser engraving are:
- Engraving Parameter: If you need a darker burn or deeper cut on the wood, you can increase the lens's focus. By increasing the focus, the density performance is decreased, and the laser's spot size is increased. This results in more wood being burned, contrary to passing them directly in gaseous form. The downside to this strategy is the loss of engraving quality and power.
- Cutting Parameters: By adjusting your cutting parameters accordingly, you can know your laser's engraving quality. To achieve this, run a brief test of the desired result by sketching a rectangle with rounded corners on a piece of paper and put this in a laser. For 3mm thick wood, the average settings for cutting this material would be 10mm/s and 20 power for a 60W. If this is not ideal, the user can lower the speed or increase power. If the machine is properly tuned and settings are ideal, Max Power settings should not surpass 60%. For 80/100W models, after being properly tuned, settings for cutting 3mm thick material would be 10mm/s and 15 max power. Again these are recommended settings that could be adjusted. If a user wants a faster job they can increase both speed and power by small increments.
- Material Preparation: When engraving wood with a laser wood engraver, a cloud of sticky dust forms on the engraved material, and this is not good for the engraving as it not only causes stains on the wood surface but also causes the machine to malfunction. Therefore, it is advisable to use an application tape all over the wooden surface to serve as a protective layer during the engraving process. When the process comes to an end, you peel off the tape and clean the material's surface. Application tape is not ideal for small engravings because you will remove many small parts at the end of the engraving, which can be very strenuous. Rather, it is used for large engravings.
- Mirror Alignment: The laser beam is emitted from the CO2 laser tube and reflects off of three mirrors before passing through the focal lens, which directs it onto your target material. Over time, the mirrors can become misaligned, leading to a loss in laser power, or even creating a slanted cut where you expect a straight cut. It’s a good idea to check your mirror alignment after about every 40 hours of use.
- Right Optics: Choosing the optimal optics with accurate focusing is imperative in wood engraving as it is a sublimation process. It is advisable to use a shorter focal length lens to achieve finer details, for example, 1” and 1 ¼” focusing distances. For most wood engraving tasks, both engraving and cutting, a 1.5’’ focal length lens will get the job done. For higher efficiency cutting a 2" focusing distance focal lens is recommended. However, the material thickness should be put into consideration when cutting through wood. The thicker the wood, the longer the lens’s focal length.
- Compressed Air: It is strongly advised to use compressed air when cutting wood. However, not all wood laser engraving jobs use it. The laser's cutting quality can be enhanced using a small diameter nozzle, which helps protect the lens and compressed air on the cutting gap by instantly removing the gas and dust. For laser etching, minimal air assist flow is preferred. For enhanced laser cutting, a stronger air assist is better.
- Cleaning: As unimportant as this sounds, it makes a huge impact on the laser machine's efficiency. Wood dust contains excessive oils and resins, which leaves behind a sticky film that attracts even more dust. This debris will accumulate on your laser path’s mirrors and significantly reduce your laser power. Smoke and fumes can build up on the focal lens which will make it heat up more and eventually get damaged if not cleaned properly. Cleaning your mirrors once a week and focal lens twice a week is much more important than you might imagine.
- Streaking: Streaking may seem beautiful in zebras, but we can’t say the same for wood engraving. Streaking renders your effort useless because the inconsistent background finish makes the engraving less noticeable. The streaking gains more attention than your work. Always choose wood with little or no streaking and consistent grain. Wood with clean, clear, and consistent grains have minimal dark and light streaks. Woods with a low level of streaking produce better engraving results than woods with a high streaking level.
While some other factors are peculiar to your workpiece, these factors highlighted above are the cogent and most important ones. Therefore, you must ensure that they are well accounted for before going on to laser engrave your wooden piece. Nonetheless, getting the best laser wood engraver could be a little challenging, and that's where OMTech comes into play. We have dedicated time to develop and manufacture the best laser wood. More so, our products are user-friendly such that you have no trouble operating or setting them up. When you purchase our laser machines, you get so much more in power and quality. Plus, our machines’ versatility and flexibility make them great for beginners embarking on their laser wood engraving journey. We remain among the best in the industry.