Page 72 - Welding of Aluminium and its Alloys

62 The welding of aluminium and its alloys

4.7 CNC CO 2 laser cutting machine. Courtesy of Messer Griesheim.

performed with mechanised or automated systems using remote control
there is only a limited risk of fume exposure for the operator. However, a
laser cutting system generally has a very high usage and fume extraction
will be required to control the general fume level within the shop.
The voltages used in laser equipment are sufficiently high to present a
serious risk of electric shock. Access panels should be secured and suitably
marked to highlight the risks. Only authorised and trained personnel should
be permitted access to the equipment for repair and maintenance purposes.
A typical laser work cell is illustrated in Fig. 4.8.
There are two hazards associated with laser radiation which, depending
upon the wavelength, can damage either the eye or the skin. The radiation
can damage the retina and/or the cornea, particularly the shorter wave-
length radiation which can be focused by the lens of the eye on to the retina.
Exposure of the skin can result in burns.With high-power lasers these burns
may be deep and can cause permanent damage. To prevent such damage it
is generally necessary to position the laser inside a suitable enclosure with
interlocks to prevent access when the laser is operating. Screening of the
CO 2 laser beam can be provided by clear glass or acrylic screens. Tinted
welding screens are required for the solid state lasers since the radiation is
closer to the wavelength of visible light than that of the gas laser. Personal
eye protection for the operator is also recommended, selected to filter out
the appropriate wavelength of laser light.