There are many different types of acrylic out there for both rotary and laser engraving. These acrylic types include extruded, cast, mirror, and multi-ply. Multi-ply acrylic is typically an extruded acrylic consisting of two or three different colors layered on each other. It may also be called multi-layer or two-tone acrylic depending on who you talk to. You will often see two different versions of this material. One will be for use with rotary engraving machines and one for laser engraving machines. I want to clarify that rotary engraving materials are meant for machinery that operates with a spindle and tooling. This can often be confused with the rotary term for lasers, which is for cylindrical objects. Make sure that you are using the correct type for your machinery. In this article, we will be focusing on the version meant for laser engraving. With that in mind, let’s get into my five tips for working with multi-ply acrylic.
Table of Contents
Materials Used
This is a list of all the materials that were used in the process of making this video. These items may contain affiliate links. If you decide to purchase from Enduramark, you can save 10% by using code: MAKEREEPS10
Machinery and Settings Used
This is a list of all the machines and their respective settings that were used to create this project. These items may contain affiliate links.
- Machine Model
- Epilog Fusion Edge 12
- Raster Settings Used
- Speed: 80%
- Power: 40%
- DPI: 500 DPI
- Dithering: Stucki
- Raster Settings Used
- Epilog Fusion Edge 12
Video Tutorial
My 5 Tips
Tip 1 – Take off the plastic coating
Every piece of acrylic, no matter what type, comes with either a paper or plastic film on it. With the multi-ply materials, there will be a plastic film on the engravable side of the material. When you go to machine the material, I recommend taking this plastic film off. By removing this film, you will directly engrave the top thin layer of material instead of machining the plastic film first. There are two main reasons why you should remove this film.
1. If you leave it on during the engraving process, the laser will engrave through the plastic film and melt it. As it melts it will travel into the path of the laser and will continue to get engraved more which will make it adhere to the acrylic itself. This results in a paste-like consistency that will be incredibly difficult to clean and you will never get a great result this way.
2. The second reason you should remove it is for consistency. As you machine, this film will tend to lift in areas as it heats up causing it to move and result in inconsistent engraving. Not only will it turn to a paste-like consistency but it will also have inconsistent engraving results.
I highly recommend experimenting with a couple of different colors for yourself and seeing first-hand what happens when you take it off or leave it on.
Tip 2 – Turn off the air assist
CO2 lasers have an air assist system that is usually driven by a compressor. The compressor itself is sometimes built into the laser but more often, it is an additional piece of machinery that is connected to the laser via an air hose. This air assist system helps keep materials from flaring up or catching on first. CAUTION: If you turn off the air assist, you need to monitor the machining process to ensure and shut it down if you start to see larger-than-normal flare-ups. Be careful any time you shut this off.
In the image below you’ll see two engravings. The engraving on the left was done with the air assist turned on while the one on the right was done with the air assist turned off. Let’s start with the engraving on the left. As the engraving is occurring, fine dust is created by the machining process. As the laser engraves through the red layer, that red layer is becoming dust that is then sucked up by the exhaust system. Here in lies the problem with the air assist. As that dust is being created, the air assist is blowing the dust around and it is landing back on the material. When it lands on the material, the laser is then re-engraving the dust at the same time it is engraving through that red acrylic. This leads to the engraving having that color in the second layer in addition to dust surrounding it. While you are able to wipe the loose dust off, the dust that was hit by the laser will embed itself into the second layer causing it to be permanently embedded into the acrylic.
In the image on the right, I shut the air assist off, meaning that the dust is sucked up by the exhaust without being blown around the material, and by laser engraving it from the bottom to the top, the dust is leaving the material before it has a chance to land back on top of it. This will produce the cleanest engraving result and ensure that you aren’t engraving the dust back into the second layer.
Tip 3 – Try using a clean-up pass
I’m just as guilty as anyone else of trying to make it through materials in a single pass because I want to machine as quickly as possible to improve throughput and therefore profit. However, this is one material where I would advise against that strategy. Due to the material being extruded, as you engrave it you will start to see very small lines at higher powers meaning that instead of a nice white look in this example, it will be visible lines throughout the engraving. Your customer won’t like this look and it takes away from the quality.
In the image on the left, I used 100% power and got through the entire red layer in one pass. When I did this, it did make it through the red layer but I could clearly see individual machine lines which aren’t easy to see in this image. Think of an inkjet printer nozzle check where you see each individual print line instead of a solid black image. This is essentially what is happening in the engraving. You will see a nozzle check style result using high power and trying to get through this layer in one pass.
In the image on the right, I used a lower power for a first pass to get rid of the majority of the layer and then followed it up with a clean-up pass at a slightly higher speed to get rid of the rest of that layer. The downside to this method is that it increases how long it takes to machine your product, but it typically results in a much better quality engraving. While we all want to make products as quickly as possible to get them shipped out, I encourage you to take the time to test different methods with this material to find the best results for your needs.
Tip 4 – Machine it out of focus
This tip may be something you haven’t heard of as a lever that you can utilize. When we talk about laser engraving or cutting, we always talk about how the material needs to be in focus with regard to the lens to get the best results. However, that isn’t always the case. Each lens size has a specific distance that the material should be away from the lens to have the correct focal point. You can think of this like a flashlight. As a flashlight shines, it spreads out the further it gets away from the flashlight itself. As a laser beam goes through the lens, it starts to spread out at an angle little by little. The closer you are to the lens, the narrower that beam spot will be. The further away you are, the wider that beam spot will be.
When it comes to engraving multi-ply acrylic if you lower the table a few clicks, it will move further away from the lens causing the beam spot to be wider and machining a slightly wider path each time it passes. This can be very useful with this material. These wider paths that are engraved will overlap each other giving the final engraving a smoother look. The downside to putting the machine out of focus is the lines and details will get slightly larger in the engraving meaning that line thicknesses will be slightly thicker. If you look at the image below, you will see that some of the lines in the engraving on the right are slightly bolder and thicker than on the right. This can provide a great aesthetic in some cases. Try it out for yourself in a more drastic level to see the effect in action.
Tip 5 – Use acrylic cleaner post engraving
After engraving, it is a good idea in general to clean the engraving. You can do this with just a cloth, water, or even acrylic-specific cleaners. There are a lot of options when it comes to doing this. If you figure out the settings well enough, you often don’t need a cleaner, but if you notice dust or anything else in the engraving, cleaning it post-engraving will help achieve a better result.
There are two cleaners that I have found to be pretty good. The first is Enduramark Green and the second is NOVUS. These cleaners are specifically designed to clean the surface of the acrylic without harming the acrylic itself. Make sure that if you are using a cleaner, it is not going to melt or damage the surface. When cleaning, use a shop cloth like a microfiber cloth or blue shop towels that won’t leave fibers. Don’t use things like normal paper towels as they will leave lint and fibers behind on the acrylic.
Finished Project
There are a ton of ways to get good engraving results on multi-ply acrylic. The most important thing is to make sure you take the time to test the material with your machine to figure out what works best for your setup. What works for me and my machine, won’t be the exact same for you. It will take time to figure it out and you will have some costs when it comes to using materials to do that, but I guarantee you that it will reduce a lot of frustration when you start to make products for your customers.
