In this tutorial, we will show you what to consider when relief engraving with a laser and how to achieve good results.
What is a relief engraving?
A relief engraving means a deep engraving with differing heights, which are created by gray shades in the graphic. The Trotec laser automatically regulates its performance using these grayscales and thus generates different heights in only one pass. Relief engravings are a real eye-catcher and make any application more attractive. They are ideal for gift items, jewelery or as add-ons for goblets and trophies.
Preparing the data and sending it to the laser
You can generate data by using grayscale fillings and gradients, which are sent to the laser via the process type "relief." Any shades of grey from 0 to 100% black can be used, which produces different heights in the material. Grayscale gradients create flowing transitions of these different heights.
The Trotec laser regulates the output power via the grayscale in the graphic. The darker the graphic, the more power is delivered. The brighter, the less power. For the laser, 100% black means 100% power - i.e. 100% of the value defined as power in the parameter database. 40% black means 40% of the defined power, 18% black means 18% power, etc. The screenshot shows examples of what files for relief engravings can look like. Feel free to download our test files here.
If you need high-quality data or photo representations for relief engravings, they should be created in a 3D program, because such programs generate extremely fine gradations at gray steps. This is a complex process. There are companies that offer this sort of individual data creation, e.g. www.gantryco.com
Which materials are suitable for relief engraving?
The engraving of a relief can be performed with materials that have the same layer structure throughout or are completely permeated with color and thus have a uniform appearance. The most suitable are:
Oak is less suitable. Due to the fact that its annual rings differ in density, the relief engraving results in an inhomogeneous engraving pattern. Alder is also not recommended for relief engraving. It is very soft and discolors quickly, making the overall appearance of the relief difficult to see.
Engraving process
For relief engraving on wood, we recommend the following method (details are based on the use of the Speedy360, 80 watt laser): Engrave your desired graphics in 3-4 passes with high performance and low speed (p 100%, v30%) to create the desired depth of your relief. Finally, we recommend one or two rounds at low power and high speed. (p 60%, v100%). this will allow you to engrave away the smoke residue.
If you want to achieve very deep engraving, we recommend that you first engrave the cutting contour and only perform the deep engraving in the second step.
Cleaning
Clean your laser-engraved relief with a toothbrush, using water and soap or detergent. Brush generously over the relief and simply scrub away the traces of powder. Make sure not to use too much water and dry your workpiece well, e.g. using compressed air. Otherwise the piece of wood could lose its shape.
TIP: Creating a wood relief engraving with color change
You can also create a relief engraving in wood to achieve a color change. For this purpose, we recommend that you clean the workpiece thoroughly after the relief engraving, as described above. This will remove the smoke traces that would otherwise impair the subsequent engraving result. Then place the cleaned and dried workpiece back in your Trotec laser and engrave with the standard values Solid Wood "black" from JobControl®. The integrated z-offset value of +6mm is important for achieving a nicely discolored engraving result. If the effect is too low, increase the z-offset value.
Relief engraving acrylic
Relief engraving on acrylic creates an elegant effect on trophies or other applications. When relief engraving acrylic, it is important to work without additional Air Assist (= OFF) and with a z-offset value, so that the material does not become cloudy or acquire a milky-white discoloration.
Engraving process
This data is based on the use of the Speedy360, 80 watt laser: Use a slow engraving speed in combination with high power (p=90%, v=10%) and switch off the Air Assist when engraving. This gives the material sufficient time to melt and -- depending on the performance of your Trotec laser -- produces an excellent texture in the first pass. Further passes create an even deeper three-dimensional effect. Equally important is the use of a z-offset value of +2mm to +4mm. This preserves the transparency of the acrylic.
Cleaning
Clean the finished acrylic workpiece under running water with a toothbrush to remove any dust from the cracks.
Application examples of relief engraving
An application example for a relief application made of wood can be found here: DIY sample Balloon Trophy
This video shows relief engraving on wood on our Canadian Trotec youtube channel.
