Como Se Genera Un Rayo Laser

Laser Cutting Fundamentals

TRUMPF Inc. A World Leader In Laser Technology

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals TRUMPF Laser Presentation  Why Laser Processing  Types of Light  Types of Industrial Lasers  CO2 Laser Theory  RF - Excitation  Laser Resonator Design  The Cutting Process  Processing Parameters  Height Regulation System  Cutting Techniques  Difference in CO2 vs. Nd:YAG Lasers (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Why Laser Processing?  Minimum set-up time  Fast processing speeds  High part tolerances  Quality edges and finish  No part distortion  Flexibility and versatility  Increased competitiveness  Quiet  Laser precautions (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Types of Light Incandescent

 Many different light frequencies  Diffused in all directions

Laser Beam  Single light frequency  In phase and same direction (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Incandescent vs. Laser Light Focused Power Measurement

1cm focal length

100 Watt light bulb 100 Watt laser beam

0.08 Watts/cm2 800,000 Watts/cm2

0.013cm diameter

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals 3 Basic Parts To Any Laser

 Excitation Method  Gain Medium  Optical Resonator

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Two Types of Industrial Lasers  Gas Laser - CO2 as the Laser Medium 

10.6 µm wave length



Powers up to 40,000 Watts



Beam transmission with mirrors

 Solid State Laser - Nd:YAG as the Laser Medium 

1.06 µm wave length



Powers up to 4,000 Watts



Beam transmission with fiber optic cable

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals CO2 Laser Theory 3) Energy level increases from excitation and collisions 2) Add in excitation

N2

4) Photon is emitted at a high energy state CO2

CO2

CO2

5) CO2 molecule is cooled and brought back to ground state by He

CO2 N2

N2 CO2 He

He

Energy Levels

1) Molecules at ground state

6) Process repeats (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals CO2 Laser Non-Lasing

N2

CO2

He

 Molecules at rest  Gas mix ratio 

He (18)



N2 (6)



CO2 (1.5)

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Initial Lasing

N2 CO2

 Excited N2 molecules collide with excited CO2 molecules  Unstable CO2 molecules releases energy by emitting a photon of light  Photons bounce around in resonator (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Avalanche Effect (Stimulated Emission)

 Photons collide and emit other photons in the same direction  Eventually hit a mirror and reflect back  Optics are aligned so photons bounce back and forth (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Total Lasing (Light Amplification)

 Lasing occurs when photons are traveling back and forth between the optics

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Laser Output (Radiation) Front mirror (output coupler)

Rear mirror

 Laser beam exits resonator through an optical coupler  The output optic is 60% reflective 40% transmissive (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Electrode Uniform Discharge O-ring Seal Gas In

Electrode

RF-excitation Anode

O-ring Seals

O-ring Seal

Gas In

Gas Out

Cathode Discharge Gas Out

O-ring Seals

DC-excitation (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals RF- Excitation Benefits  Low maintenance and high reliability of resonator and optics  Electrodes mounted external to discharge  Fewer O-ring seals  Mode stability  Consistent mode throughout the power range  Better efficiency  Uses less laser gas  Flexible power control  High frequency pulsing (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Laser Resonator Optics

Linear

Square Folded

Maximum power output depends on the resonator length! (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals TRUMPF Laser Resonator Design Bending Mirror Turbo Pump Gas Cooler Frame Rear Mirror Output Mirror

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Beam Quality I

 The beam quality influences the cutting performance  Thin and medium thick material cut best with a TEM00 mode (Gaussian distribution) and narrow focussing  For thick plate (above 0.75”) a TEM01 mode (ring mode) is the optimum beam for best cut quality

Fundamental Mode TEM 00 x

nearly Fundamental Mode

I

TEM 00/01*

x

I

Ring Mode TEM 01* x (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Beam In

The Cutting Process

Lens Assist Gas

Height Regulation

Work piece

Nozzle (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Before Cutting Begins  90% of power is reflected  10% of power is absorbed  Material melts immediately

Reflected laser power

 Molten pool is called “The Keyhole”

Absorbed laser power (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals As the Cutting Starts

 The Keyhole is blown away by the assist gas  10% of power is reflected  90% of power is absorbed (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Laser Cutting  Cutting begins when the beam is through the material  The beam, or workpiece, or both, must move to create the desired cut path

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Processing Parameters  Laser power  Cutting speed  Assist gas

- type of gas, pressure

 Focus

- length, position

 Nozzle

- diameter, standoff

 Pulsing

- frequency, time delay

 Piercing

- time, power ramp, standoff (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Defining Process Parameters  Material type  Thickness  Edge quality  Other process parameters

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Types of Metal for Laser Cutting  Mild Steel  Aluminum  Stainless  Aerospace Alloys  Coated Steels

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Types of Laser Power Control  Pierce 

Start the cut



Small hole drilling

 Continuous Wave (CW) 

Process cutting

 Pulse 

Small areas



Reduce heat input

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Process Parameters Cutting Gas  Type 

O2 or N2 or shop air

 Pressure 

0 to 450psi

 Nozzle 

Hole size (more volume)



Flow design



Stand-off distance / length (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Process Parameters Focus / Lens  Focal length lens 

Stand-off distance



Power density



Working depth of field

 Focal height control systems

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Focal Length Definition Spot diameter = 2D

Focal length = 2L L Spot diameter = D

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Capacitive Height Regulation System (DIAS III)

220 V

Digital outputs

Digital inputs

Z-drive

to NC/PLC Z-position meas. syst.

Z-position meas. system

DIAS III-System

Nominal value Z-axis

Frequency meas. signal Oscillator

Bitbus fiber-optics cable (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Laser Cutting Head  Height Regulation  DIAS insures a constant standoff between nozzle and material  Quick cutting head change  Fast and precision adjustment by means of micrometer screws and dial indicator  Change of lenses or cutting head reduced to a minimum  Nozzle cooled with compressed air 1 2 3 4

0001 5"D1,5"  HD

2 1

X adjustment screw with scale Clamping pin Y adjustment screw with scale Nozzle

3

1

Serien­Nr. 0001 Ident­Nr. 256133

4 (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Focal Height Control Systems Ball Rollers  Positive control method  Rolls on material  All materials  Allows for multi-layer cut  Simple design  Difficult to process very close to edge  Flexible nesting nearly impossible  Scratches on top of material (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Focal Height Control Systems Spoon  All materials  Simple / Inexpensive  Rides on material  Difficult to process very close to edge  Flexible nesting nearly impossible

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Machine System Configuration  Sheet mover (tracker) - moving sheet in X and Y  Hybrid

- moving pallet in X only

 Flying optics

- moving cutting head in X and Y

 Flat sheet or tube and pipe  Multi-axis  Robotics

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Maximum Thickness(in(ininch) inch) Maximum Cutting Cutting Thickness 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0

aluminum stainless mild steel

TLF 1800 t

TLF 2400 t

TLF 3000 t

TLF 3800 t

TRUMPF RF-excited Laser Resonator

TRUMPF RF-excited Laser Resonator (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Cutting Rules of Thumb for Mild Steel  Gas type 

Oxygen

 Pressure 

10 to 60 psi

 Nozzle 

0.040” dia.

 Focus lenses 

5” or 7.5”

 Speed / Power relationship (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Other Cutting Techniques  High pressure cutting 

Air / Inert gas up to 450 psi



Oxide-free surface edge

 Thick material cutting 

Longer focal length lens



Lower gas pressure

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Quality Cutting Goes Beyond Process Parameters  Beam Quality / Stability  Best focus ability  Optimizes parameters  Best part quality  Smallest nozzle diameter − Closer to material − Less gas consumption  Reliable process results  Beam Delivery System  External mirror maintenance  Mirror alignment  Lens removal and alignment

Re-alignment

Downtim e

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Quality Cutting Goes Beyond Process Parameters  Assist Gas Quality  Gas purity  Reliable gas flow  System Performance  Smooth accurate motion system  Interface and control  Reliability  Material Quality  Carbon steels  Rust and scale  Grease penciled or painted material (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Cutting of Small Holes 

Cutting in pulse mode with a frequency of 10Hz



Diameter smaller than material thickness



High accuracy of contour

Ø = 0.2 in.

Example: Material Material thickness Smallest hole diameter

Mild steel 0.5 in. 0.4 in. x thickness (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals SprintLas - Increase in Productivity: 40 - 50% ®

0

Machine: Laser: Material:

1

2

3

4

5

6

7

8

9

L3030 TLF 3000t Mild steel

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

Material thickness: 0.060 in Cutting time w/out SprintLas : 78 s Cutting time with SprintLas : 43 s ®

®

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals ToPs 100: Programming System for Lasers  Geometry data input from CAD-systems (DXF, IGES, ...)  Integrated Know-How:  Cutting parameters (SprintLas, common line, ...)  Technology tables  Job-related nesting; "true shape" or “rectangular” nesting processor  Automatic processing definition  Automatic collision check (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Difference in CO2 vs. Nd:YAG Lasers  Gain Medium  Excitation Methods  Resonator Design  Difference between CO2 & Nd:YAG  Operating Costs  Applications - Cutting  Applications - Welding  Choosing between CO2 & Nd:YAG  Future Developments (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Excitation Methods Electrode Discharge

CO2

Electrical

Electrode

Gas In

Gas Out

Discharge

Nd:YAG

Light (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Resonator Designs CO2

Nd:YAG

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Differences Between CO2 & Nd:YAG  Maximum output power / Pulsing  Mechanical  Wavelength  Beam Quality / Focus ability  Maintenance / Reliability / Consumables  Application

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Operating Costs 3000 W - CO2

3000 W - Nd:YAG

 Laser Gases

 Flash lamps

 Process gas (welding)

 Ion Exchanger

 Beam delivery purge / components

 Protection glass

 Maintenance /hour  Electrical  Total cost per hour $10

 Maintenance /hour  Electrical  Total cost per hour $12

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Applications - Cutting CO2

Nd:YAG

 Sharper edge

 Smooth cut edge

 Fast cut speeds

 Cuts highly reflective materials copper, silver, gold

 Can cut up to 1 inch thick mild steel  Best in metals > 4.0mm

 Best in metals < 1.0mm

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Applications - Welding CO2

Nd:YAG

 Best in deep penetration welds

 Faster in thinner materials (<1.0mm)

 Good for mild and Stainless Steel

 Absorption in Aluminum is 12% to 80%

 Absorption in Aluminum is 5% to 62%  Can use longer focal length lens (TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Choosing Between CO2 & Nd:YAG  Look at the application first  Weigh the importance of each lasers’ characteristics  Consider overall costs and not just initial purchase

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)

Laser Cutting Fundamentals Future Developments  The gray area between CO2 and Nd:YAG will increase as YAG’s increase in power  Flexible cable for lower power CO2 beam delivery  Diode pumped Nd:YAG lasers (eliminates flash lamps)  40 kW CO2 lasers with cut beam quality

(TAI 11/11/98 - Laser-Fundamentals-V1.ppt - 23/AS)