Process Pros and Cons

Question 1

What are the advantages and disadvantages of using a laser for hardening compared to electron beam, induction, flame, and arc?

Answer 1

Pros:
- minimum part distortion
- selective hardening
- no quenching required
- case depth controllable
- eliminates post processing
- improved fatigue life

Cons:
- high equipment cost
- coverage area restricted
- multiple passes can lead to inconsistent hardening

Question 2

What are the advantages of laser shock hardening over shot peening?

Answer 2

• Less surface roughness
• No embedded particles
• Hardening can be done in corners
• No recycling of material (shot)
• No equipment wear
• Radioactive materials can be treated (shot would get contaminated)

Question 3

What are the pros and cons of using laser marking for colour change?

Answer 3

Pros:
- no chemicals
- very fine detail
- multicolour possible - unlike with anodising

Cons:
- cost of laser equipment
- slower than printing
- unknown long term properties of surface

Question 4

What are the pros and cons of using lasers for marking?

Answer 4

Pros:
- very fast
- low running cost
- consistent high quality
- process is cleaner than painting, inking etc
- no tool wear
- can mark soft and hard surfaces

Cons:
- fume collection, treatment and disposal

Question 5

What are the pros and cons of laser alloying?

Answer 5

Pros:
- controllable energy delivery and localised heating
- non-contact and flexible
- thick layer alloying

Cons:
- control of repeatable alloying composition is difficult
- inefficient for large area coverage

Question 6

What are the advantages of laser cladding compared to traditional forming or machining?

Answer 6

• reduced no. of pre-production stages
• greater material efficiency
• cost not dependent on complexity
• no tool wear
• complex internal geometry possible

Question 7

What are the advantages of laser cladding to other cladding techniques like 3D printing?

Answer 7

• wide range of metallic materials can be used
• standard powders can be used
• fully dense part is produced in one stage (no post processing)
• self quenching (fine microstructure) - good final material properties
• small heat affected zone and little part distortion

Question 8

What are the disadvantages of laser cladding?

Answer 8

• accuracy
• surface finish
• part size limitations
• initial cost of equipment
• low deposition rate
• part reorientation required for overhang structures

Question 9

What are the advantages and limitations of laser welding?

Answer 9

Pros:
- non-contact
- high precision
- high speed
- no contamination
- small heat affected zone
- no filler material required
- high tensile strength
- high depth/width ratio

Cons:
- high capital cost
- weld thickness less than electron beam welding
- machined joint required to ensure good fit-up
- accurate seam tracking required

Question 10

What are the advantages of using a DOE ?

Answer 10

• allows beam distribution to be optimised for process
• rapid beam distribution change
• no maintenance
• increased depth of field (+-30mm compared to +-12mm with equivalent Gaussian lens)

Question 11

What are the alternate methods to laser drilling?

Answer 11

• mechanical drilling
• electric discharge machining
• electro chemical machining
• ion and electron beam machining

Question 12

What are the pros of laser drilling?

Answer 12

• faster than alternatives (holes drilled in fraction of a second)
• non-contact
• can drill very hard substrates
• very small hole sizes with high aspect ratios

Question 13

What are the limitations of laser drilling?

Answer 13

• high capital cost
• limited material thickness to 50m
• heat affected zones, recast layer and microcracking can occur
• spatter deposition
• tapering often occurs