In this tips and tricks guide we'll show you what to consider when relief engraving with your laser machine and how to achieve good results with the technique.
A relief engraving is a deep laser engraving with differing heights, which are created by gray shades in the graphic. Trotec laser machines automatically regulate its performance using these grayscales and thus generates different heights in only one pass. Relief laser engravings create eye-catching designs and make any application more attractive. Relief engraving is ideal for gift items, jewellery or as add-ons for goblets and trophies.
Data can be generated 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 will produce different heights in the material. Grayscale gradients create flowing transitions of these different heights.
Trotec laser machines regulate the power output via the grayscale in the graphic. The darker the graphic, the more power is delivered, while brighter graphics receive 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. Download our free test files below.
Tip for high-quality data or photo representations
If you need high-quality data or photo representations for your relief engraving, they should be created in a 3D program. This is because such programs generate extremely fine gradations at gray steps., which is a complex process. There are companies that offer this sort of individual data creation, an example of which being www.gantryco.com
Laser engraving a relief can be performed with materials that have the same layer structure throughout or are completely permeated with colour (thus having a uniform appearance). The most suitable materials for performing relief laser engraving on are:
Types of wood suitable for wood engraving
Relief laser engraving on wood typically produces impressive results. FOr creating a relief engraving in wood we recommend using a particularly hard wood., such as:
WOods less suitable for relief engraving
Oak is a less suitable material for this processing method. Due to the fact that its annual rings differ in density, the relief engraving will produce an inhomogeneous engraving pattern.
Alder wood is also not recommended for relief laser engraving, as it is very soft and discolours quickly. This makes the overall appearance of the relief difficult to see.
Laser engraving process
For relief engraving on wood, we recommend the following method (the following details are based on using a Speedy 360, 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 laser engraving results, we recommend that you first engrave the cutting contour and only perform the deep engraving in the second step.
Post-processing : 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 colour change
You can also create a relief laser engraving in wood to achieve a colour change. To achieve this we recommend that you clean the workpiece thoroughly after the relief engraving, as described above. This removes the smoke traces that would otherwise impair the subsequent laser engraving result. Then place the cleaned and dried workpiece back in your laser machine and engrave with the standard values Solid Wood "black" from JobControl®. The integrated z-offset value of +6mm is important for achieving a nicely discoloured engraving result. If the effect is too low, increase the z-offset value.
Relief engraving on acrylic creates an elegant effect for applications including trophies. When relief laser 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 discolouration.
Laser engraving process
This data is based on the use of an 80 watt Speedy 360 laser machine: Use a slow laser 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 laser machine - produces an excellent texture in the first pass. Further passes create an even deeper three-dimensional effect.The use of a z-offset value of +2mm to +4mm is very important here, as this preserves the transparency of the acrylic.
Clean the finished acrylic workpiece under running water with a toothbrush to remove any dust from the engraved areas.
Find an example of an application which uses relief engraving:
In this video our colleagues at Trotec Canada relief engrave an emblem into wood.