Waterjet and
Abrasivejet pictures (Page 11):
Image Tracing
On a previous page, I showed
how you can manually trace a
geometric logo to quickly go from a file on the Internet, to an actual
high-precision part. Below is a much
more complex image that shows where the automatic image
tracing software is more appropriate. I would definitely not want
to have to trace this Chinese paper dragon cut-out by hand!
Here is an
example of how Automatic Tracing works for a drawing such as
this:
First, it's best
to start with clean black-and-white artwork. The
artwork should ideally be very high-contrast, with what you want to
make in black, and everything else white. (or vise versa). The
cleaner the input, the easier it is to do. You can trace
photographs, and messy color artwork and such also, but the results may
not be so good, and probably will require more work on your part.
Anyway, here is
the basic process:
#1 - Take a
picture of what you need. (Or scan it in with a
scanner, or find the artwork on the Internet, etc. At any rate,
you need the artwork in digital format such as BMP files, or JPEG, GIF,
TIFF, etc. For this picture, I used a 3 megapixel camera.
#2 - (Above)
Load the picture into your image tracing software
(sometimes called "raster to vector" software.) In this example,
I am using OMAX Intelli-TRACE(r).
#3 - (Above)
Crop the image so only the portion you want will be traced
(optional step)
#4 (Above) If
necessary, adjust image and remove noise (Optional)
#5 (Above) The
software traces the edges of high contrast automatically
for you. (With optional steps to control this process.)
There are a lot
of 3rd party image tracing software packages out there
such as Adobe Streamline, Cutting Shop from Arbor Images, WinTopo,
etc. (Search for "Raster to Vector" using your favorite search
engine to find them). For the above example, I show OMAX Layout,
since that's software I'm involved in writing. Another package
that I found gives excellent results is a program called "Gems" from a
company
called CadCraft in Sweden. (A $2500.00 package that includes
CAD / CAM / Nesting / Image Tracing, and other nice tools useful for
waterjet users.) I have not had much of a chance to use
Cutting Shop from Arbor Images, but I have heard good things about it
as well. It's also a little bit cheaper at around $900(?) or so
last I checked. Adobe Streamline is significantly cheaper at
$150.00, but does not always produce such good results, and it is
strictly for image scanning and tracing, and no longer supported by
Adobe. There are also a few free packages out there on the
Internet that give mixed results.
Some things to
look for when shopping for raster to vector software:
- How easy are the results obtained
- How well does the software deal with noisy images, or low
resolution images, etc.
- How good is the output? Does it contain "zillions of lines"
and lots of garbage that will need to be cleaned up by hand, or does it
give nice smooth and clean output suitable for a tool path?
- What file formats can it accept as input?
- Try before you buy. If they don't give you a free trial
where you can try it on your own files,
then take that as a red flag.
Anyway, once the
image was converted to vector format, I clicked on
"Finished" to bring it into my CAD/CAM software, so that I could turn
it into a tool path:
With nearly 1000
holes, it took the computer about 2 or 3 minutes to
calculate the above tool path sequence, considering things such as
collision avoidance. That said, though, automatic tool path
planning is rarely perfect, and it's a good idea to check the results
and make corrections "by hand", if you see the that the computer
decided to do anything stupid. Also, since this part started out
as a photograph, it's a good idea to spend some time making sure it's
doing exactly what you want.
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Lettering
One neat way to
promote your business, is to cut out the names of all
of your potential customers, and then distribute them as gifts.
It's quick to do, and probably a great way to get your foot in the
door.
Below are a bunch of names cut from 1/2" (12mm) aluminum. This
particular font is an OMAX "Tool Path Font" called "EzName", and is
designed to quickly and
easily cut out someone's name as a single connected part without a lot
of programming or machining
time:
Tube cutting:
Abrasive
waterjet machining is not only limited to flat parts.
Below is some high pressure waterjet tubing, with the ends cut off with
the abrasivejet:
Above: High
pressure waterjet tubing cut in half with an
abrasivejet. The abrasivejet does a pretty decent bur-free job of
cutting, but there is a slight blemish. Notice the way the
texture of the metal is slightly changed underneath the hole.
This is because as the jet cuts across the hole, it gets slightly
disturbed, and fans out a little. The end result is that it cuts
a little bit differently on the other side. Plugging the hole
with a dowel might improve the cutting, but in this case, the results
were fine.
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