NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/sci/electron/22256

Internet Message Format | 1993-01-08 | 2.3 KB

Path: sparky!uunet!caen!kuhub.cc.ukans.edu!wellison
From: [e-mail]
Newsgroups: sci.electronics
Subject: Re: Laser cutting steel, what about glass?
Message-ID: <[e-mail]>
Date: 8 Jan 93 11:05:07 CST
Organization: University of Kansas Academic Computing Services
Lines: 36



>Probably everyone has heard of applications where laser beam is used to
>cut steel plates. But are there similar applications to cutting glass?
>Will the same setup do for glass or is it too hot?
>
>>I have a couple m^2 of raw factory mirror and would be interested in
>turning it into pieces of art. Would like to hear if anyone of you has
>experience in this field.
>
>How powerful does a laser have to be in order to cut 10 mm steel?

--
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Metal fabrication lasers are almost all CO2 lasers at 10.6u wavelenght (far IR),
however some metal work can be done with pulsed ND-YAG lasers at 1061Nm. The
power density of the beam to cut 10mm steel would require 620 joules/(square
cm) which would equate to a 4200 watt beam at 1.5 mrad divergence. Lasers in
this power range are fast axial flow CO2 lasers (at cost of around $500,000).
The cutting of glass though presents some rather unique problems. The laser has
more than enough energy to cut the glass, but at IR wavelenghts, the beam would
tend to pass through the glass rather than heat it. Problems of reflection from
the glass surface, which would degrade the power of the beam is also a problem.
Ways of getting around this is to use a graphite type of coating on the glass
to enhance absorbtion and reduce reflection. Another problem is the glass
fracturing under the tremendous heat from the beam at a localized point. To
date, I don't know of any commercial application using lasers to cut the glass,
but they do use them to etch it. The beam can be attenuated to precise depth
and power levels for etching without fracturing. Woodcarving lasers (also CO2)
are around 20 to 30 watts and again, the power level can be adjusted for depth
of penetration into the wood. These guys can be bought for $3500 new and are RF
waveguide type CO2's. We have such a beast in my lab here at KU and I have been
known to 'woodburn' with it during those quit moments ;-)

-=-= Wes =-=-