Using Microwaves to Drill Through Glass

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."

Comments

Max Depth?

[BoBaBrain]

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.

Re:Max Depth?

[AlecC]

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.

CPU key fobs

[Perdo]

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.

Not a big deal

[Sinbit]

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?

Re:Not a big deal

[geordieboy]

It's probably a lot cheaper - the article says
that this microwave device is not more expensive
than a mechanical drill. How much does a 500W laser cost?

Re:Not a big deal

[Idarubicin]

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.