Dr. L. K. Gaafar

2. Outline: Laser Technology Processes: Cutting Drilling Welding Rapid Prototyping Other: Precise Measurement, Heat Treatment, Scribing General Advantages and Disadvantages Economics Safety measures

3. Laser Technology Laser is an abbreviation of “light amplification by stimulated emission of radiation” Laser Beam operation are based on producing high energy laser beam that melts and vaporizes the material. Can be used to cut, weld, drill by varying both power and beam intensity, focus, and duration.

4. Laser Technology

5. Laser Technology A relatively weak light flash bounces back and forth between the mirrors causing the lasing material to produce energy (photons) These photons accelerate the intensity of the beam of light which will cause the beam to cross the partial mirror after reaching a certain intensity. A lens focuses the beam on the work piece causing portions of it to melt and vaporize.

6. Laser Technology Beam Generation

8. Laser Technology High Power. Monochromatic: Same wave length (same color). Coherent: light waves in phase. Non-contact.

9. Laser Technology Reflectivity. Thermal Conductivity. Specific Heat Latent Heat

10. Laser Technology 1. Hard Optic Delivery (Moving workpiece): relatively inexpensive. can accommodate large heavy lasers. operate quick (20 m/min). but heavy large piece limited.

11. Laser Technology

12. Laser Technology

13. Processes

14. Processes: Cutting Cutting starts by drilling a hole then moving the beam in a programmed path. A stream of assist gas is used to: blow the molten metal Cool workpiece Minimize heat affected zone

15. Processes: Cutting Mild steel: Oxygen Stainless steel: Oxygen or nitrogen (nitrogen leaves an oxide free edge that can improve weldability) Aluminum: Nitrogen Titanium:Argon (an inert gas because of its reactivity) Nonmetals: Air or inert gas

16. Processes: Cutting Cutting Temperature could reach 11000oC. The more uniform the thermal characteristics of component the better the cut and less thermal damage to the material. Cutting Speed depends on: (can reach 1000in/min in nonmetals) Material Thickness

17. Processes: Cutting Cutting Capabilities: (Thickness) Acrylic and composites 1 in Aluminum ¼ in Mild steel 0.625 in Stainless steel 5/16 in Titanium ¼ in

18. Processes: Cutting Applications

19. Processes: Cutting Advantages: Narrow kerf and heat affected zone Although cutting produces a thin recast surface, no post-cut finishing is required Economic alternative for materials that are difficult to cut by conventional methods(plastics, wood, and composites) Narrow slots Closely spaced patterns Does not require smooth surface

20. Processes: Drilling The repeated pulsed laser beam vaporizes the material layer by layer until a through hole is formed. Larger diameters can be contoured after drilling the through hole if desired. Blind holes are theoretically possible but not practical. Hole diameter depends on material thickness. Cutting and drilling are performed on the same unit.

21. Processes: Drilling Drill micro-holes in metals as thick as 0.1in L:D ratio: 10:1 Cutting Speed decreases? depth increases but: Generates irregular holes Recast layer increases Heat affected zone increases

22. Processes: Drilling Applications: Bleeder holes for fuel pump covers Drilling holes in delicate medical materials Drilling holes in small polymer tubes Drills tiny holes in turbine blades of jet engine

23. Processes: Drilling Advantages: Burr free holes Eliminates drill breakage and wear Drills in difficult to access areas, curved surfaces and parts incased in glass Drills holes of almost any shape High quality and precision holes Close tolerances Limitations: Holes up to 1” deep in plastics and ferrous metals, and 0.125” in reflective materials.

24. Processes: Welding High intensity beam produces a cause the material to melt and flow into the channel (gap) as the beam advances. Careful joint preparation is needed to produce the thin gap. forms a very thin heat affected zone and little thermal distortion.

25. Processes: Welding Solidifies quickly Filler material is used if gap is large. Inert (Shielding) gas is may be used to prevent oxidation of weld pool. Can be used to produce deep penetration welds Effective with thin workpiece

26. Processes: Welding Applications Razor blades: 13 pinpoint welds 0.5 mm in diameter Electronic circuits

27. Processes: Welding Advantages: Does not require vacuum Better quality of weld Beam easily shaped, directed, and focused No direct contact is necessary to produce a weld Encapsulated (with transparent containers) and inaccessible areas can be welded Can be made with access to only one side of joint Increase speed and strength of welding Produces maximum penetration and minimum distortion in the material

28. Processes: Rapid Prototyping 3D CAD Software is used to slice a 3D model into 2D horizontal layers packed on top of each other A laser beam then starts to build the first layer by melting and fusing powder metal.

29. Processes: Rapid Prototyping The layer then solidifies and fresh power is added on top of it for the next layer The laser beam proceeds building the physical prototype layer by layer until it is done. Model is cleaned, cured, and then can be used for testing in environments similar to that of the final product

30. Processes: Rapid Prototyping Applications:

31. Processes: Rapid Prototyping Advantages: Speeds up the design and manufacturing process. Reduces product development cost. Allows for instant feedback to design engineers. Allows for design corrections at an early stage. The model is used in pre-production planning and tool design.

32. Processes: Rapid Prototyping Disadvantages: The generated model has shrinkage cracks The model has high hardness, which makes it brittle Thick walled structures can’t be built up very well

33. Processes: Measurements Helium-Neon laser beam is split into two beams one beam goes to a reference point and reflects back using a retro-reflector, while the other hits the object. Then the two beams are recombined, and their relative motion creates a frequency shift. This shift is then converted into a distance measurement.

34. Processes: Measurements Applications To align and calibrate machine tools Useful in Large assembly jigs Non-contact: used to inspect hot rolled material

35. Processes: Heat Treatment Produces hardened surfaces For wide variety of geometries Can work on limited area Produces little distortion

36. Processes: Scribing Composed of series of closely placed holes To produce lines and characters with different fonts on materials As wide as laser beam Set to a specific tolerance depth

37. General Advantages Operates in fully automated environment Minimum heat affected zone compared to other thermal processes Clean Small clamping force is applied Can be used with metals, nonmetals, and composites Excellent surface quality Minimum thermal stresses on the material No tooling required

38. General Disadvantages Requires specially trained operators Not for mass metal removal processes Requires greater control of joint tolerances Expensive equipment Consumes much energy

39. Economics Expensive equipment Requires skilled operators Compensated by: Fast material removal rate (0.5-7.5m/min) ? high production rates Finishing costs are eliminated Can be automated ? reducing operational costs

40. Economics Cost of Laser Cutting Machine New: $200,000 Used: starting $30,000 CNC: $750,000

41. Safety Measures Lasers can burn and blind: Eyes and skin should be protected from scattered beams Even low powers can cause damage to retina Operator should wear gas masks to protect against generated fumes