Here, we will be talking about what you need to consider when relief engraving with your laser machine, and how to achieve desirable results every time.
A 'relief engraving' is a deep engraving with differing heights, depending on what effect you are going for. This is all created by grey shades in the graphic. Trotec lasers automatically regulate their own performance using these greyscales, generating different heights in the one pass. Relief engravings are unique and eye-catching and can lift the quality of any application. They are ideal for gifts, jewellery and add-ons for goblets and trophies.
You can generate data using greyscale fillings and gradients, which are all sent to your laser machine via the 'relief' process type. Any shades of grey, from 0 to 100% black, can be used. This will produce different heights in the material, creating an interesting texture and look. Greyscale gradients can create flowing transitions of these different heights.
Trotec laser machines regulate the output power via the greyscale in the graphic. The darker the graphic is, the more power is used. The brighter the graphic, the less power used. This means that 100% black will mean 100% power, 40% black means 40% power, etc. The screenshot provided shows specific examples of what relief engraving files might look like. You can always download out test files below:
High-Quality Data / Photo Presentations
If you require a high-quality data or photo representation for relief engravings, you should always create them in a 3D program. This is because 3D programs can generate extremely fine gradations at grey steps. Keep in mind that this is a very complex process. There are even some companies out there that offer this kind of individual data creation: www.gantryco.com
Suitable Types of Wood
Relief engraving with wood usually produces the best, most impressive results. We suggest using somewhat hard woods to create the perfect relief engravings:
Not-So-Suitable Wood Choices
Oak is less suitable for relief engraving. Because its annual rings always differ in density, the relief engraving results will be inconsistent. Alder is also not a great choice - It is very soft and discolours easily, making the overall appearance of the relief very difficult to make out.
The Engraving Process
For wooden relief engraving, we suggest the following method (based on the Speedy 360, 80 Watt): Engrave your desired graphics in 3 to 4 passes with high performance and low speed (p100%, v30%) to create the desired depth to your relief. We also recommend one or two rounds on low power and high speed (p60%, v100%). This will allow you to engrave over the smoke residue.
If you desire a deep engraving, we suggest that you first engrave the cutting contour. Only perform the deep engraving when you've reached the second step.
We suggest cleaning your laser-engraved relief with a toothbrush, using a little bit of water and some mild soap or detergent. Brush generously over the engraving and scrub away any traces of powder. Remember not to use too much water and ensure that you dry your finished piece very well. Otherwise the it could lose its shape.
Creating a Wood Relief Engraving with Colour Change
You can also create a wooden relief engraving with a colour change. For this purpose, we suggest cleaning your workpiece thoroughly following the relief engraving, as described above. This will help to remove any remaining smoke residue that might otherwise impair the subsequent engraving result. Then, place the cleaned, dried workpiece back inside your Trotec laser machine and engrave with the standard 'SolidWood black' in JobControl. The integrated z-offset value of +6mm is very important for achieving a desirable, discoloured engraving result. If the effect is too low for your liking, increase the z-offset value until you are satisfied.
Acrylic relief engraving creates an elegant effect for trophies or similar applications. When relief engraving acrylic, it is very important to work without any additional Air Assist (=OFF) and with a z-offset value. This is to help the material avoid becoming cloudy or acquiring a milky-white discolouration.
The Engraving Process
(Data is based upon the use of the Speedy 360, 80-Watt laser machine): Use a slow engraving speed, combined with high power (p90%, v10%), and switch off the Air Assist when engraving. This will give the material sufficient time to melt and, depending on your laser's performance, produce an excellent texture in the first pass. More passes will create a deeper, 3D engraving effect. Remember, it is equally important to use a z-offset value of +2mm - +4mm. This will preserve the transparency of the acrylic.
Clean the completed acrylic workpiece underneath running water with a toothbrush to remove any remaining dust particles inside the tiny cracks and grooves.
Here, you will find an application example using relief engraving:
DIY Balloon Trophy
The following video displays relief engraving with wood, done by our friendly Canadian staff.