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Thread: 352nm UV laser: will it cut scotch tape?

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    Default 352nm UV laser: will it cut scotch tape?

    Greetings laser gurus!

    I am a laser noob with limited hands-on experience with CO2 and fiber lasers, but no theoretical background, and currently trying to solve a practical problem: I need to build a robotic system that would open corrugated cardboard boxes arriving to a distribution center. Basically, a box from a contract manufacturer comes in, it needs to be cut, opened and then goods from the box are extracted and sorted.

    The problem that currently completely blocks me is how to open the box. Vibro-knives are a possibility, but they have pretty poor reliability record (blades have to be changed frequently) and they sometimes damage goods inside the box.

    The hope is that I could use a galvo-driven laser + camera to identify box location and strategically cut tape + cardboard to allow easy box unloading. Here comes the question: what kind of laser would work best for this kind of application?

    The important consideration is fire safety: the system is going to be running unattended for hours, and catching fire would be a pretty sad event.

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    ... laser-cutting depends on wavelength, power and absorption rate inside the material -- some hundred Milliwatts on a focus as of 0,1mm diameter are enough, if the wavelength will be absorbed ("dark" or UV absorbing material) ... but all the safety/precaution measures will render this impracticable

    Why not using a ceramic cutter blade?

    Viktor
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    Quote Originally Posted by VDX View Post
    Why not using a ceramic cutter blade?
    Viktor
    Ceramic blade would be a good idea, but unfortunately it's not possible to control the "quality" of the incoming boxes. Some of them have metal stables in addition to tape.

    By the way, this is how state-of-art blade-based box opener machines look like:


    They are not very reliable in what they do, and that's why there is always a human right next to the machine to finish the robot job. The hope is that with lasers, it would be possible to cut and open the box completely automatically.

    As for safety measures: let's suppose, we want to be less dangerous than a regular CO2 laser cutting wood unattended, where everyone has their own story of "we came back from launch and it was already over", but not aiming for NASA-level safety.

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    Given the critical nature of your application I would have a chat with the Applications Lab Engineers at Synrad (Co2) , IPG (fiber) , Light Conversion (Femtosecond) and Coherent / Spectra Physics for UV and Excimer. This is by no means an exhaustive list.

    It sounds like you want to ablate (vaporize) material rather then Pierce and Cut (burn and push material out of the kerf with air or inert gas). Many cardboards are made using a sodium silicate adhesive that is somewhat fire retardant while others are not.
    You need an assist gas to blow material through or out of the cut, and in your case it sounds like it may be better to have that gas come from inside the package. I've never seen some one do it backwards.

    You'd end up cutting, but then probably have to follow up with a fine spray of water for paranoia reasons,

    This just does not sound like a good idea to me.

    Ultrasonic Knife with a Sapphire or carbide tip might be a better idea.

    Steve
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    Quote Originally Posted by mixedgas View Post
    This just does not sound like a good idea to me.

    Ultrasonic Knife with a Sapphire or carbide tip might be a better idea.
    Hi Steve,

    thank you for your thoughtful reply!

    Blade-based solutions are widespread in the industry, so yes - it's known to mostly work. The issue is that nobody succeeded in making a reliable box opener that way and a human is always needed. In our application, human help would only be available 3-4 hours / day and the rest of the time the mini-distribution center is supposed to function autonomously.

    Let's suppose we are willing to accept risks and just eat the cost of the packages that caught on fire, but still want to go with lasers for autonomy reasons. Would you find this feasible?

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    Quote Originally Posted by fuzzy View Post
    Hi Steve,

    thank you for your thoughtful reply!

    Blade-based solutions are widespread in the industry, so yes - it's known to mostly work. The issue is that nobody succeeded in making a reliable box opener that way and a human is always needed. In our application, human help would only be available 3-4 hours / day and the rest of the time the mini-distribution center is supposed to function autonomously.

    Let's suppose we are willing to accept risks and just eat the cost of the packages that caught on fire, but still want to go with lasers for autonomy reasons. Would you find this feasible?
    I've never had the chance to do ablation of cardboard, Which is why I'm sending you to professionals. Not the answer you wanted, I know. Don't rule out diamond wire saws, either.

    Steve
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    Quote Originally Posted by mixedgas View Post
    I've never had the chance to do ablation of cardboard, Which is why I'm sending you to professionals. Not the answer you wanted, I know.
    I do speak with 3 vendors at the moment including IPG, but it seems that for a random person from the Internet like me, it's easier to get a quote from them than a fair advice. It's still something that I keep doing in parallel to asking for independent opinions.


    Don't rule out diamond wire saws, either.
    This is not a bad idea, actually! Thanks - I will try to see if anyone tried using them for this application.

    It's also an idea I would not hear from a laser source vendor, which makes this thread already "profitable" to me.

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    I'd laser perforate/ ablate with a zillion tiny holes, then follow by a knife. I know that is/was feasible in the cigarette industry at one time.
    I just don't know whom, what, when, where and how.

    I go to church with a fellow who designs boxes, and I'll ask him. I know they use C02 for some tasks.
    I'd redesign the box to allow lasing.

    Think out of the box. :-)

    Good luck...

    Steve
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    ... I've done cardboard ablating, engraving and cutting with blue 2W, 3.5W and 6W laserdiodes or 85Watts CW- or 20Watts pulsed (20W averaged from 10kW pulse peak power) fiberlasers - the more power, the faster.

    What's another problem with "undefined" materials -- if you cut through, theres's noting, what will stop the beam from burning the space inside too!!

    So a carbide/ceramic/diamond cutter still sounds as best option for me ...

    Viktor
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    Quote Originally Posted by mixedgas View Post
    I go to church with a fellow who designs boxes, and I'll ask him. I know they use C02 for some tasks.
    That would be amazing! Thank you in advance.

    I'd redesign the box to allow lasing.
    Unfortunately, the boxes are from multiple third-party vendors (mostly from China). There's a zero chance we can influence them to change the box design.

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