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Using Microwaves to Drill Through Glass

Posted by CowboyNeal on from the hot-stuff dept.

Linux_ho writes "UPI is reporting that Israeli researchers have developed a drill that can melt a small hole in glass, ceramics, or concrete with no dust or noise. Nature.com reports that it doesn't work very well with good heat conductors or materials with very high melting points, but the researchers envision a wide variety of manufacturing applications, and possibly some medical uses as well."

15 of 140 comments (clear)

  1. And spy movie uses! by ottffssent · · Score: 5, Funny

    Can it be suction-cupped onto a piece of glass to cut a perfect circle out?

    --
    High-speed Road Trip (18.000KPH)
  2. Excellent by Anonymous Coward · · Score: 5, Funny

    I've always wanted holes in my windows.

    1. Re:Excellent by hplasm · · Score: 5, Funny

      Get Windows XP. The holes included are numerous.

      --
      ...and he grinned, like a fox eating shit out of a wire brush.
  3. So... by iomud · · Score: 5, Funny

    What kind of time are we talking about for the average hotpocket? I'm just thinking about the immediate benefits here.

  4. Max Depth? by BoBaBrain · · Score: 5, Interesting

    The article mentions that it can only drill to a depth equal to a quarter of its wavelength. Why is this?

    Surely it could also drill at depths of .75, 1.25, 1.75 etc.

    --
    I am a Karma Library.
    1. Re:Max Depth? by AlecC · · Score: 5, Insightful

      As I read the article, below 1/4 wave, the drill bit behaved more like a hosepipe - microwave frequency oscillations in the conducting drill bit produce an intense microwave field just beyoind the point of the bit - probably using the Near Field bits of Maxwell's equations, which I never did understand. Above 1/4 wavelength, the drill bit functions as a tradition aeriel, radiating the energy sideways from the drill bit. It is not that some sort of effect doesn't exist at the end of the bit, it is that far to much energy escapes sideways to make it worthwhile.

      --
      Consciousness is an illusion caused by an excess of self consciousness.
    2. Re:Max Depth? by Ilari · · Score: 5, Informative

      From the article: "The device is limited to a penetration depth of a quarter of the wavelength of the microwaves used -- in this case, about an inch. If the drill bit is any longer, the microwaves are no longer beamed forward but instead radiate in every direction like an antenna."

      If I understand correctly the drill works as a highly directive antenna - beaming microwaves towards the material to be melted. The drill needs to be short to achieve good directivity.

      Different frequenciens have different penetration depths - that is, how deep the electric field or radiation energy can penetrate into the material which is being "drilled". The penetration depth also depends on the conductivity of the material, so different materials can have very different penetration depths for the same frequency.

      I think the depth of "a quarter of its wavelength" is just a very approximate rule given to journalists. It is more of a comparison rule: the penetration depth is comparable to a quarter of the wavelength. (Although I'm not sure why, the penetration depth is proportional to the square root of the wavelength, if I remember correctly.)

      After they have reached the penetration depth, they need to move the antenna/drill forward. So of course they can drill deeper holes than that, but not at a time.

      What kind of an "antenna" are they using? To achieve good directivity, they would need to use "traveling wave antennas" (or whatever they are called in english), I'd imagine. Does anybody know any details of this?

    3. Re:Max Depth? by AlecC · · Score: 5, Interesting

      The antenne *is* the drill bit - and the quarter wave rule is to stop it acting as a real antenna and broadcasting microwaves all round the room. Below 1/4 wavelength, some undecribed mechanism creates intense heating just below the drill bit, which is where you want to drill. They can't move the drill forward without moving the (presumably non-conducting) chuck, or all their micropwave energy will radiate sideways, gently heating that which they do not want to heat and failing to heat that which they want to drill.

      --
      Consciousness is an illusion caused by an excess of self consciousness.
  5. CPU key fobs by Perdo · · Score: 5, Interesting

    I doubt that steel conducts the heat away too fast. I'd wager that the steel conducts the RF radiation itself. Just like this device has an antenna, steel would be an antenna too. Not exactly impedance matched, but certainly enough to prevent the steel from being heated except across the entire piece.

    --

    If voting were effective, it would be illegal by now.

  6. In other news... by Anonymous Coward · · Score: 5, Funny

    ...Burglars and Bankrobbers Corp. raised it forcasts for the financial year 2003 after a R&D breaktrough.

  7. Not a big deal by Sinbit · · Score: 5, Interesting

    I was doing the same thing over 10 years ago for my Master's thesis with a pulsed CO2 laser with ~500W time averaged output. What is the advantage of using a microwave beam over a CO2 laser?

    1. Re:Not a big deal by Idarubicin · · Score: 5, Interesting
      What is the advantage of using a microwave beam over a CO2 laser?

      There are a number of advantages. First is price--you can use off-the-shelf microwave oven pieces for most of a microwave drill. Granted, carbon dioxide cutting lasers are also available essentially off the shelf from a limited number of suppliers, but they tend to run in the tens of thousands of dollars.

      Durability. Laser tubes don't tend to be happy about being moved about a lot. They contain optics that are very sensitive to misalignment.

      Size. Microwave sources for this application would be quite a bit smaller than a carbon dioxide laser, especially when you add in all the ancillary equipment in my next point. In addition, combining size and durability makes a much more portable tool.

      Limited complexity. No delicate optics. No vacuum system. No water cooling system. No mixed lasing gas to deal with.

      Safety. Lasers can remain well collimated for significant distances--you can make holes in your coworkers from across the room if you're not careful. A microwave drill as described isn't acutely dangerous beyond an inch or two from the end of the drill bit. (There might be heating effects beyond that distance, but reflex action--Ow! It's hot! I'm moving my hand now!--would likely be sufficient to protect you. You need the same level of common sense that it takes to operate a band saw--don't put your fingers near the business end!)

      So, that's why microwaves would be advantageous. That said, CO2 lasers can perform extremely well, as long as you don't have to move them to the field. Manufacturers already exist for the lasers, and it's a proven technology.

      --
      ~Idarubicin
  8. Re:Microwave and Me by Anonymous Coward · · Score: 5, Informative

    Common mis-understanding about microwaves. Cooking "from the inside out" is misleading. They only penetrate 3-4 cms (Might want to check exact). This is why cooking large items in a microwave is problematic.

    You risk burning the outside of the food while the inside is still under cooked. For things like roasts, etc it is still better to use the slow and steady approach as the temperature has more of a chance to distribute evenly throughout the food, ensuring an even consistency. But I digress.

  9. Re:Microwave and Me by GigsVT · · Score: 5, Informative

    Your warning is a good one, but generally you do feel "warm" if you step in front of an active feed horn, before any damage is done.

    You are very correct about the blindness though, looking directly into a hot horn can blind you before you knew what happened. Your eyes resonate right around the microwave range and absorbe them readily.

    --
    I've had enough abrasive sigs. Kittens are cute and fuzzy.
  10. See what happens deep inside Israeli underground.. by gorehog · · Score: 5, Funny

    ...top secret weapons labratories?

    Physicist #1: Oh man, this Dr. Brown's Cel-Ray bottle would make a killer bong!

    Physicist #2: Ah, they shatter on the drill press, I tried it last week.

    Physicist #3: (eyes red and bleary)Hey, what's wrong with the microwave? I wanna make this popcorn.

    Physicist #1 & #2 (in harmony):Microwave?