Main Features of Laser Cutting Process
1) Laser cut kerf is very narrow resulting in material saving.
2) Has very narrow heat affected zone (HAZ) and therefore gives low thermal distortion. Gives machine smooth cut surface reducing the need for subsequent trimming.
3) The cut has square edges.
4) There is no tool wear (contact free energy transfer).
5) The work piece does not need holding against tool drag. Work holding demands are reduced to merely a locating role.
6) Possible to cut through friable, brittle, soft or hard material or composites with ease.
7) It is a non contact method with no cutting forces and is ideal for cutting flexible material such as clot h, rubber, corrugat ed cardboard, etc.
8) Non directional, cuts equally well in all directions and can start cutting anywhere.
9) Blind cuts can be made.
10) The cutting speed is fast compared to other methods as the light beam is inertia less.
11) Multistation operations from one laser are possible.
12) It is easily automated by numerical control.
There are five different ways, in which a laser can be used to cut different materials:
a) Vapourisation: the beam energy heats the substrate to above its boiling point and material leavesas vapour and eject - this requires 10 times the energy of (b)
b) Melting and Blowing: the beam energy melts the substrate and a jet of inert gas blows the melt out of the cut region - this requires around twice the energy of (c)
c) Burning in reactive gas - the beam energy heats material to the kindling temperature, which then burns in a reactive gas jet; as in (b) the jet also clear the dross away - requires around 10 times energy of (d) for some materials.
d) Thermal stress cracking or controlled fracturing - the beam energy sets up a thermal field in a brittle material ego glass such that
it can guide a crack in any direction.
e) Scribing - variant on (a) whereby blind cut is used as a stress raiser allowing mechanical snapping along the scribed lines.