This tutorial will provide an overview of some of the information to consider when processing relief engraving with a laser machine, as well as recommendations for achieving the best results.
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, promotional items, jewelry or as add-ons for goblets and trophies.
Data can be generated by using gradients and grayscale fillings, which are communicated to the laser by the process type “relief.” Any shade of gray ranging from 0% all the way up to 100% black is compatible and will produce variations of height within the material. Furthermore, grayscale gradients will create flowing transitions between differences in height.
The Trotec laser machine will regulate power output through the grayscale of the graphic, and darker graphics will deliver greater amounts of power while brighter graphics deliver less power. The parameter database will define the graphics grayscale as “power,” meaning that 100% power refers to 100% black. 40% power will refer to 40% black, 18% power will refer to 18% black, and so on. The accompanying screenshot illustrates examples of what a relief engraving will look like, and our test files can be downloaded here.
Recommendation for high-quality photo presentations or data
If you are looking for high-quality photo or data representations for relief engravings, use a 3D program for this complex process because they can produce extremely fine gradations at gray steps. Many companies will offer this type of individual data creation, ex. www.gantryco.com
Compatible wood types
Wood adapts naturally to the relief engraving process and will produce highly impressive results. Hard woods will generate the best results when relief engraving:
Less compatible wood types
Due to the fact that its annual rings vary in density quite greatly, oak is less suitable for relief engraving due to the fact that it creates an inhomogeneous engraving pattern. Alder is another wood that is not compatible for relief engraving, and it will often discolor rather quickly as well as the engraving will be rather difficult to see because of its soft nature.
The engraving process
When relief engraving into wood, we suggest the following method to create the desired depth of your relief (details are based on the use of the Speedy360, 80 watt laser): Engrave the desired graphic using 3-4 passes with low speed and high performance (v-30%, p-100%). Next, process 1-2 rounds using high speed and low power (v-100%, p-60%) to engrave away any smoke residue.
If you are looking to produce and even deeper engraving, we suggest engraving the cutting contour first followed by the deep engraving after.
For additional information and assistance with laser settings or parameters, visit Trotec Laser parameters
You will want to clean the laser engraved relief to remove any excess residue, dirt or debris, but do so delicately to ensure the wood does not lose its shape. We recommend using a toothbrush with minimal amounts of water and mild soap or detergent, and gently scrub over the relief to remove any traces of powder. The workpiece should also be thoroughly dried, and we recommend using compressed air if available.
TIP: Creating a wood relief engraving with color change
You can also produce a relief engrave into wood to create a color change. With this intention, we suggest thoroughly cleaning the workpiece once processing is completed, as outlined in the previous step. In doing so, any smoke traces that would otherwise impair the subsequent engraving results will be removed. Next, once the workpiece has been cleaned and is fully dry, place it back into 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, and if the effect is too low consider increasing the z-offset value.
Relief engraving on acrylic creates a high-end and elegant effect on trophies and other applications. To avoid cloudiness or producing a milky-white discoloration when relief engraving acrylic, make sure to work with the additional Air Assist switched off and with a z-offset value.
This data is based on the use of a Speedy360, 80 watt laser machine: Use a combination of high power (v=10%) with slow engraving speed (p=90%), and switch the Air Assist to off when engraving. In doing so, this provides the material sufficient time to melt and produces excellent texture in the first pass, depending on the performance of your Trotec laser. Using additional passes will produce an even deeper 3-dimensional effect. To preserve the transparency of the acrylic, use a z-offset value of +2mm to +4mm.
Once laser processing is completed, clean any dust remaining on the finished acrylic by using running water and a toothbrush.
An application example for a relief application engraved into wood can be located here:DIY sample Balloon Trophy
This following video located on our Canadian Trotec YouTube channel shows a relief engraving into wood.