co 2 laser basics

CO2 Laser BasicsNeil Hansen

Sierra Laser DesignCameron Park, CA(530) 350 - 0941

CO2 Laser Tube, The Heart of the Machine

The Laser is becoming the workhorse of the maker movement.

Can process a wide variety of materialsProduces a good surface finish on cutsCan engrave designs on surfacesVery accurate CNC processUses simple 2d drawings, shallow learning

curve

Stable C avity Design ( < 2kW )

+ -

H igh Voltage Pow er Source

100% R eflectiveM irror

Partia lly R eflectiveM irror

Cooling Jacket

Laser C avity

19% - N77% - H e

= +

+ = + +

Electron

Very Excited CO M olecules2

Less Excited CO M olecules2

Relaxed C O M olecules2

Photon

CO Laser Basic Principals2

The G as M ixtureis bom barded w ithe lectrons. As the gas m olecules becom e excited, they start tospontaneously re laxand re lease photons.

+ =

O ptical Path

M irror M irror

M irror

FocusingLens

W ork

Laser

M irrors and Lensare ZnSe(Z inc Selenide)

W hat do you do w henyour ligh t eat g lass???

• The CO2 Laser outputs in the Infrared spectrum (10.6 µm)

• The light is monochromatic• The energy density is very high! (1kW of

Input = 1.4 mW / CM2 with a typical focus of 0.3mm)

SAFETY! (This is a class 4 laser)Laser Light from a CO2 Laser is invisible

• Eye protection designed for the proper wave length should always be worn when working with the Laser

• When adjusting optical path two people should work as a team, one adjusting and one to make sure that an unfocused beam is not; burning another part of the machine, starting a fire in the shop, cutting through the shop wall, cutting through the building next door, pets, people, etc…

• This is general advise … be safe, have fun.

Let’s Get To Work!What can we do with

this Thing?

• Lasers < 300 W are generally used for cutting Non Metallic Materials

• Wood, Acrylic, ABS, Plywood, Synthetic foams, …etc! are readily cut with a Laser

• Lasers cut by one of 3 methods, or a combination of them.– Vaporization (acrylic)– Chemical Degradation (Wood, ABS, Many Plastics)– Melt Shearing (Metals, Some Plastics)Air Flow is VERY important to the process!!!

The thickness of material to cut and the cutting speed are governed by the amount of energy needed to vaporize/decompose/melt a volume of material. This relationship boils down to the cutting speed equation:

V=PQt-B

V=maximum cutting speed

P=Laser Power

T=Material Thickness

Q & B = Experimentally derived constants

SoftwareAny 2d drawing application that can output; .PLT, .AI, .DXF, .DST, .BMP, …ETC canbe used to generate designs for the laser.

Gimp – open sourceCorel Draw – industry standardAuto Cad Light – industry standard 2d CAD Turbo Cad – very versitile 2d and 3d CAD

LaserCut Software

SOME FUN STUFF FROM MAKERS FAIR 2014. LASER CUTTING WAS USED TO PRODUCE A WIDE RANGE OF PRODUCTS AND PROTOTYPES.

ReferencesCO2 Laser Cutting, 2nd Ed, John PowellLaser Material Processing, 4th Ed, Steen, MazumderHurricane Lasers User ManuelLaserCut Software ManuelMAKERS, The New Industrial Revolution, Anderson

Questions ?