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Thread: thin metal engraving/burning/marking

  1. #1
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    Default thin metal engraving/burning/marking

    Hi,

    I am new to this forum, have just joined in hope, that I could get some good advice from experienced laser users

    I am trying to find a suitable laser diode, which would allow thin metal engraving. I was hoping I could reach my goal using laser diode NDB7875, 9mm package - power up to 5W (heatsink + ventilator for cooling). Second option, to use 405nm laser diode at lower power, which delivers more light power in respect to electrical power for its greater focus of the beam. I want to avoid using more powerful and co2 cooled laser diodes.
    I will mount the laser on a small, precise (0.0004inch/step), 2 axis CNC with a small working area (2x2 inch).

    The material:
    I want engrave metal RF shield, which is a material mixture of copper, zinc, tin and aluminium.
    My fear is that this metal surface is too reflective, therefore, laser diode won't deliver enough power to engrave. I know that anodized aluminium can be engraved using the diodes described above, but its surface is really non reflective.
    My advantage here is that metal RF shield (metal sheet) is really thin (cca 0.0014 inch). Meaning, the heat delivered from laser beam won't be dissipated too fast. I believe this can help with collecting enough power for engraving/burning

    I am attaching example of an RF shield I would like to engrave. You can see that the surface is quite shiny.
    Also, a QR code and text on top, which is exactly the stuff I'd like to burn on with laser.
    Click image for larger version. 

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    I will really appreciate any tips/suggestions on this matter.

    Thanks,
    Jaks

  2. #2
    swamidog's Avatar
    swamidog is online now Jr. Woodchuckington Janitor III, Esq.
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    your best bet is to use cermak marking compound instead of directly etching your metal with laser

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    I agree that using compound is an effective choice if small amount of pcs has to be marked.

    What I am trying to do, is to install laser marking tool in the automated line. So, applying and cleaning compound after laser marking would be kinda difficult - I'd prefer to skip it.
    Searching the web I am afraid I am left with c02 cooled or fiber laser, which is more expensive and bigger

  4. #4
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    I have a 60w co2 laser. if you want to send me a piece of your material, I can try to mark it.

    but... I can almost guarantee it won't.

    co2 is good for blasting off paint or anodizing, but lousy for direct marking of metal. fiber laser maybe, but be prepared to add another 5x to your budget.

    Quote Originally Posted by Jaks View Post
    I agree that using compound is an effective choice if small amount of pcs has to be marked.

    What I am trying to do, is to install laser marking tool in the automated line. So, applying and cleaning compound after laser marking would be kinda difficult - I'd prefer to skip it.
    Searching the web I am afraid I am left with c02 cooled or fiber laser, which is more expensive and bigger

  5. #5
    swamidog's Avatar
    swamidog is online now Jr. Woodchuckington Janitor III, Esq.
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    "shiny metal" can become a mirror if you're not careful.

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    ... I'm engraving shiny metals either with fiberlasers or cover them with black paint and then with 2W@445nm-diodes ... but have then to remove the paint with acetone after finishing.

    The blue 2W-diodes are much better suited for this than 3.5W- and 6W-diodes, because of their better beam specs!

    Viktor

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    For production line rate marking, your looking at Q-Switched Nd:YAG or a Fiber laser. Stop thinking that a few watts of a continuous wave Laser with hobbyist level beam quality, and with no peak power will engrave metal rapidly, consistently, or accurately... I would not take on your task with anything less then 40 watts of Q-Switched laser. You can always dial down power or duty cycle, but you cant make a silk purse from a sow's ear.

    I have a few 1064 IR laser marking installs out in the wild for one of my former employers, I know of what I speak. CO2 is basically out, it reflects too much from any metal.

    Steve
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    @Swamidog: I agree, shiny metal is too reflective. Thanks for your offer. I'm located in Europe though, so I'm gonna have to skip it. I'll check for some local companies, to test if co2 would be an option.

    @VDX: Makes sense. Can you tell me which model you use? Speaking about the wavelength, I've read some users suggest use of 405nm instead of 445nm (smaller wavelength, more narrow beam, results in better electrical to light power ratio).

    @mixedgas: I get your point. Getting more and more information I see that I'm gonna have to go with something more powerful, throw some more coins into this project. Q-Switched YAG or fiber seems the correct choice for my application. At this point I am afraid the project falls out of DIY domain, I will just buy a pre-assembled tool, and mount it on a big CNC.

    Tnx to all, Jaka

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    ... the fiberlasers I'm using are from IPG - 50W and 85W CW (modulated) or 16W pulsed (around 10kW peak).

    The 405nm-diodes have a much better beam quality, but with only around 300mW lack of power ... so the 445nm with 2Watts has better 'cutting' specs, but with the 405nm you can mark/engrave more bright/shiny materials, which will be problematic with 445nm for the reflectivity/translucency...

    Vikto

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