Although Fiber Lasers are being introduced to many applications at this time, most engraving lasers are of two varieties, CO2 & Q-Switched Nd:YAG.

If you are engraving in wood, plastic, paper,or glass (most organic materials) the usual choice is a CO2 laser. A CO2 generates a beam at 10.6 micrometers wavelength. This wavelength reacts better with these materials.

If you are engraving in dark anodized aluminum, either a CO2 or a Nd:YAG works well.

For metals, the common choice is a Q-switched Nd:YAG. These metals include aluminum, tool steel, stainless steel, soft steel, etc. A Nd:YAG laser produce a beam at 1064 nanometers. This is approximately 1/10 of the wavelength of a CO2 laser. Partly because of this wavelength reacts better with these materials, partly because at 1/10 the wavelength you can focus the laser to a smaller spot size and partly because of the Q-switching, Nd:YAG lasers are used for engraving metals. (Q-Switching is a method of quickly turning the beam on and off. By doing this, a laser beam with high peak power is created.) It is the wavelength, the spot size and the high peak power that allow the Nd:YAG laser beam to dig into metals.

Lasers are used for cutting many non-metal materials like acrylic, glass, wood, leather and rubber. They are also used for metals both ferrous and non-ferrous.

When cutting materials, there are a number of things to consider as follows:

1. (1) The material one is cutting.
2. (2) The thickness of the material.
3. (3) The speed at which one wants to cut.

Materials are sometimes cut using a Nd:YAG laser but the CO2 is the much more usual laser used...

See Table I for cutting rates of CO2 lasers of 100 - 500 watts power and Table II for CO2 lasers of 1500 - 3500 watts power.

CO2 Laser Cutting: 100 - 500 Watt Lasers
|--------------- Speed (IPM) ---------------|

Material	Thickness	100 Watt	200 Watt	500 Watt	Assist Gas	Focal Length
304 Stainless Steel	.010	N/A	220	440	Oxygen	2.50
	.020	N/A	110	220	Oxygen	2.50
	.031	N/A	70	140	Oxygen	2.50
	.062	N/A	N/A	70	Oxygen	2.50
Low Carbon Steel	.031	N/A	90	180	Oxygen	2.50
	.062	N/A	45	90	Oxygen	2.50
	.125	N/A	N/A	45	Oxygen	2.50
Acrylic	.125	80	160	320	Nitrogen	2.50
	.250	40	80	160	Nitrogen	2.50
	.375	25	50	100	Nitrogen	2.50
	.500	N/A	40	80	Nitrogen	2.50
Polymethyl Methacrylite	.125	80	160	320	Air	5.00
	.250	40	80	160	Air	5.00
	.500	20	40	80	Air	5.00
Glass-Reinforced Epoxy	.031	25	50	100	Air	2.50
	.062	N/A	35	70	Air	2.50
	.062	N/A	18	35	Air	2.50
Glass-Reinforced Polyester Delrin	.225	75	150	300	Nitrogen	2.50
	.750	60	70	140	Nitrogen	2.50
Fir Plywood	.375	30	60	120	Air	5.00
	.500	N/A	40	80	Air	5.00
	750	N/A	20	40	Air	5.00
	1.000	N/A	N/A	20	Air	5.00
Hardwood	.125	120	240	480	Air	5.00
	.250	60	120	240	Air	5.00
	.375	40	80	160	Air	5.00
	.500	N/A	60	120	Air	5.00
	.750	N/A	20	40	Air	5.00
Die Board	.750	N/A	20	40	Air	5.00
The listed cutting speeds are starting values which might need to be modified up or down, depending on the actual material and the desired edge quality. Please note that the assist gas is optional on all materials except steel.

Table I

CO2 Laser Cutting: 1500 - 3500 Watt Lasers
|--------------- Speed (IPM) ---------------|

Material	Thickness	1500 Watt	2200 Watt	3500 Watt
Carbon Steel	.062	210	250	300
	.125	140	180	210
	.250	65	80	100
	.375	35	50	65
	.500	30	40	55
	.625	-	32	40
	.750	-	-	30
Stainless Steel (O2 Assist)	.060	230	270	300
	.125	130	180	210
	.250	50	70	90
	.375	20	30	40
	.500	-	15	5
Aluminum	.125	40	50	70
	.250	20	28	35
Maple Dieboard (2 point kerf)	.625	65	85	-
	.750	60	80	-
Plastics	Up to 1" thick	To 350	To 400	To 450
NOTE: Reduce speed by approximately 20% When using high pressure nitrogen assist.

Table II

The typical laser used for welding is the pulsed Nd:YAG laser. These pulses are longer than the Q-switched pulse of a Nd:YAG engraving laser. Typical pulse widths are 0.5 to 29 milliseconds. Energy per pulse can range from 10 joules or less to 70 joules or more. Some Nd:YAG welders can have pulse shaping networks.

General: When selecting a laser. It is important to get a laser that has enough power and is otherwise suitable for your application. Feel free to contact Laser Resale Inc. for a free consultation.