Laser Beam Machining

Question 1

Laser Beam Machining

Answer 1

Melting and evaporating of particles from the surface of a workpiece by using the highly focused optical energy from a laser light beam

Question 2

Laser Principle

Answer 2

Each photon is capable of initiating the release of other photons, thereby forming a chain reaction
Photons have same properties such as wavelength, direction and colour
Maximum stimulated emission is achieved by reflecting photons within the optical resonator (aligned mirrors); after enough photons have been created they pass through a partially transparent mirror as an intense coherent light – laser beam

Question 3

What are the 3 main components of the Laser?

Answer 3

Gain medium (active medium)

Pump source (excitation mechanism; energy source)

Optical resonator (feedback mechanism)

Question 4

Types of Lasers?

Answer 4

• Gas Laser
• Solid state laser
• Excimer

Question 5

How many classes of Lasers are there? in order of the strongest

Answer 5

Class 1
Class 2
Class 3
Class 4

Question 6

LBM - Process Mechanism

Answer 6

• Digital CAD data is divided into layers to determine depth and contour of each cut
• Surface of the workpiece is heated and melting occurs
  Material (i. e. liquid metal) evaporates or gets removed by the impulse in liquid form at high velocity
• Machining operation is enhanced by introducing an assist gas

Question 7

List a 4 conditions LBM is dependent on..

Answer 7

Reflectivity and thermal conductivity of the workpiece surface

Specific and latent heat of melting and evaporation

Surface roughness

Wavelength of the laser beam

Question 8

Variations of Laser Beam Machining ?

Answer 8

Laser Beam Cutting
Laser Beam Drilling
Laser Beam Welding

Question 9

Advantages of Laser Beam Machining?

Answer 9

High flexibility – generally simple fixtures, low setup times

Significant cost savings possible, no tooling required, compete with EDM

Minimal stress on the workpiece; no cutting forces

Direct data input from CAD systems

Quick cycle times

Automation and 3D CNC robotics allows high volume manufacture

No special operating environment required

Question 10

LBM Limitations

Answer 10

Tapered walls when drilling deep holes

Shiny and polished surfaces cause reflection

Often impossible to avoid lots of offcuts (laser cutting); careful planning required

Medium to high equipment costs

High energy consumption

Health and safety risk; requires training, personal protective equipment