Etching Aluminum With a Waterjet

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The OMAX Waterjet at Pier 9 is capable of cutting through several inches of just about any material you can imagine at a high level of precision. But it's also capable of generating remarkable effects by etching various materials as opposed to cutting through them. In particular, metals and stones produce very different, but equally interesting results when subjected to this process. After some initial trials, I became interested in the way that the combination of material and machine transformed my intended designs and suggested a kind of adaptive working method, one that required material engagement and sensitivity to more than just the digital inputs. These material studies became the basis for one of the major projects that I completed during my residency at the Pier.

In this Instructable, I'll share the basic digital workflow for setting up files to etch, discuss some of the material considerations you should keep in mind, and review some machine setup suggestions to prevent damaging either the machine or your material, and avoid making a too large a mess.

Step 1: Software: OMAX Intelli-Etch

If you've ever used a laser-cutter before, you're likely familiar with the process of etching. You provide the software with a raster image (.jpg, .bmp, .tif or similar) and by controlling the intensity of the laser at each sampled point, the image is created. The waterjet works similarly, but with a very important difference. Instead of varying the intensity of the water stream, the software will vary the speed at which the jet moves across the material - moving faster over lighter areas in the image while slowing down and dwelling longer in darker areas.

To get started, you'll need an image file. While you can use any kind of image you like, only the grayscale values of the image will be used to generate the etching. For this reason, I convert my images to grayscale to help clarify for myself what the results might be.

On the OMAX control computer, run Intelli-Etch*. Intelli-Etch functions as a wizard. Click 'Next' on the welcome screen. On the next screen, click the folder icon and browse to your image file. After it's loaded, click 'Next' and you'll have an opportunity to make edits to contrast, invert black/white, rotate, etc. I prefer to make all these changes in other image editing software, and bring a finalized image to Intelli-Etch.

Next, you'll be prompted to define a color border, similar to a mask. Note that this feature is very limited - a mask of any complexity will likely yield unpredictable results, which you will see once you import the file into Make.

After you've loaded the intended image, define a size for your etching. The larger your etching, the more memory it will take to generate the toolpath. Note that there is a low memory limit for Intelli-Etch as it's 32-bit software. Etchings larger than approx. 24" x 24" are challenging. One other option that will affect memory consumption is the step size. Note that Intelli-Etch handles this as a percentage overlap, unlike typical CNC convention of stepover. For those with lots of CNC experience, this will require a bit of acclimation.

Lastly, adjust the maximum and minimum speeds for the etching. Like etching on a laser, it will take trials with different images and materials to tune the right settings for your project. Plan to have some scrap material on hand to use as tests. The maximum speed of the Pier's waterjet is 180 inches / minute. Minimum speed is governed only by how it will impact machine time and how deep you wish to cut into your material. Keep an eye on the time estimate for your project to prevent excessive operations. Small differences in your minimum speed can have significant impact on total time, as can inverting your image.

Finally, you'll be prompted to convert your file to code and open the file in OMAX Make. I've not found a way as of yet to save this toolpath file for later use.

*Unfortunately, the OMAX control workstation is the only computer at Pier 9 with this software as of right now, so even getting an estimate of how long your etch will take (more on this below) requires a trip to the CNC shop.

Step 2: Software: OMAX Make

The process for etching once you are in Make is very straightforward. Set your Path Start Home to wherever you'd like the etch to begin. Unlike creating parts in Layout (the standard workflow for the OMAX), you don't have the ability to define traverses to move around your file. Your Path Start Home and the beginning of your etch will always be the same point. Set your Z standoff height as usual. Double-check that your toolpath won't cause a collision between the nozzle and your material or workholding. When you're ready, begin etching and wait for your part to finish. The aluminum panel shown here measures 22" x 22" and took approximately five hours to etch, for reference.

Step 3: Hardware: OMAX 60120 Waterjet

The setup on the machine itself is not much different than a normal through-cut setup. You'll need to fixture your part in some way, making sure that you don't crash the nozzle into your material or clamping setup anywhere in the etching process. It's good policy before etching to raise the Z height of the nozzle and use the 'Go to spot on path' feature once you're in Make to ensure you're clear of the clamps.

Occasionally, you'll be working on a smaller piece of material, especially if you're just testing settings, and there's not much room for clamps. If that's the case, it's acceptable for the rubber splash guard to bump into clamps, just ensure that the nozzle within doesn't collide! Also, make sure that you flip the cup down and position it such that when the nozzle begins moving, the cup doesn't snag any of the clamps (see images).

It should be noted that etching also has the potential to produce a BIG mess VERY fast. The usual waterjet policies are still effective at minimizing the mess, but carry vastly more importance when etching, as the water that's not penetrating the material has to go somewhere. Keep the water level up as high as possible and keep the splash guard down. The splashing can be especially bad if a large amount of garnet has accumulated in the tank. Spraying water will carry this garnet airborne and deposit it all over the machine and the rest of the shop. Bad times.

If you're etching thicker stock, check to see if the max flood level will give you the necessary coverage. If not, add more water to the tank! You may want to perform this check in advance of when you plan to actually cut, as it can take 45 minutes or so to get the tank level to where you'll need it. The shop staff will thank you.

Step 4: Material: Aluminum

Aluminum was a good benchmark for initial testings of the etching process as it holds a high resolution and can preserve tiny features, unlike the other materials I intended to etch. Instead of using these qualities to produce smooth gradations and recognizable images, as this could already be easily done with more traditional CNC milling tools, by giving Intelli-Etch a noisy, grainy image, the resulting surface texture is something like a bed of nails - a kind of texture I haven't seen as a result of any machining process before.

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    4 Discussions

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    chubeyr

    22 days ago

    That is some great advice from omax. I have used omax etching software for years now.
    I am quite good using intelli etch, and quite good just etching in general.

    What can be produced with etching can be amazing.

    Intelli etch is great software, yet it takes time to know how it reacts with material. Trial and error. Yet you can save your successful work as a bts file.

    I have etched hundreds of signs. Without intelli etch and with it. Mostly out of aluminum. I find spraying paint over the etching and then quickly wiping it off makes the work pop! Paint stays in the grooves, excess is wiped off the surface. It is a good way to showcase your work.

    Brush the surface of the aluminum and you have shiny amazing art work that does not take long to cut.

    I love waterjet machines because the passion of the user is the difference between a $15/hour employee and a $40/hour employee.

    I work at a super busy waterjet shop. Hired at a very good wage. Hired at that wage because of my experience. I started the job and the two other waterjet experts quickly learned I am just as skilled as they are. They love me. Yet they were not aware of etching abilities on the machine. They told me etching does not work. Both operators have 10 years experience.

    These are great people to work with. Not narrow minded at all. Just lacked the experience or passion to learn, and knowledge to make etching work for them.

    Most people get content with the jobs they do. They know it all so time to shut off the brain, they are an expert. Work was like this when I started here. Amazing programmers and operators, that knew nothing about etching. They knew everything else though.

    So I cut a few samples at work. An hour of work on my time on a weekend. My boss asked me where I got these items from for they are really cool. I cut them at 5pm on a Saturday after a 55 hour work week. I am dumb like that, I already work massive overtime and now try to get the company more work cause I don't want to have a life outside of work ever!

    Our expert waterjet operators here are blown away with what the machine can etch. They don't know how to do it yet. Yet 10 year veterans are now so eager to learn. I will teach them.

    With a waterjet machine the possibilities are almost endless. Etching is amazing in all forms!

    Yet cutting a toilet in half was cool, cutting leather for a gymnastics club was cool too.

    I have been tasked to cut so many things on a waterjet machine thought to be impossible. I don't always succeed. I fail 5 percent of the time. Good track record when cutting stuff the machine was not designed to cut.

    Yet the machine can pretty much cut anything if the operator is skilled enough.

    I should post pictures here. I am not allowed too. Not by the website. I need customers authorization to do so. I could get sued if I post pictures. What I make is a one off for our customers.

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    JonC150

    Question 1 year ago on Step 3

    Do you know if the clamps and rails shown in the picture are an Omax system or if they were purchased from a third party manufacturer? At our shop we are currently just using weights and want to produce more accurate and smaller parts and those look like a good system to use.

    1 answer
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    pdeloreyJonC150

    Answer 1 year ago

    Hi Jon - I don't honestly recall if they were an Omax product or third-party. Maybe ping @OMAXCorp like below in the comments? Best of luck!

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    OMAXCorp

    3 years ago on Introduction

    Hi pdelorey,

    Great article! On the first page, near the bottom, you say, “I've not found a way as of yet to save this toolpath file for later use”. This is actually easy to do, but the interface for it is by default hidden, so that it won’t confuse new or inexperienced users.

    To enable the interface, you need to open OMAX Make, click on “Setup”, then “Advanced”, and then “Advanced Administrator Setup”. (Note: You may need to contact whoever is the administrator of your machine to help you get past the administrator password.) Next, click on the “User Interface” tab, and check the item, “Show CNC and Bitstream Recording Tools”.

    You will then notice that Make has a few new tools in the lower left hand corner. These advanced tools allow you to “record” actions on the machine, as well as load and save “bitstream” files, which are essentially “compiled” tool paths.

    At any rate, if you have those tools enabled in OMAX Make, then when you run the Intelli-ETCH utility, you will find a new option at the very end of the wizard that will allow you to save the “bitstream” to disk.

    “Bitstreams” are pretty much the raw I/O and motor motions for the machine, and are not meant to be human readable (sort of the “machine language” of the OMAX). You can load and save bitstreams from within OMAX Make, append them, etc., which allows making of some fairly complex paths in sort of a “teach” mode. Bitstreams can also be inserted into existing .OMX tool paths using XData #34 within your tool path, to mean “Insert bitstream here”.

    One thing quite cool you can do once you have bitstreams saved, is that you can append them to other tool paths, which can allow you to mix and match traditional vector based cutting with Intelli-ETCH elements. This is a bit much to describe here, but there is a tutorial for it in the OMAX Interactive Reference. (Just type “Intelli-ETCH: Tutorial” into the Index.)

    By the way, a great way to create height maps for Intelli-ETCH is via ArtCAM, which I believe is even owned by Autodesk now! Type in “ArtCAM” into the index of your help screens to learn a little more about that as well.