**6. Applications**

In general, the use of lasers found in many applications includes chemical, biochemical, optics, medical, military operations, polymer sciences, nuclear physics [8–12] and so on. In manufacturing, lasers are successfully applied for material removal, metal joining, cladding and alloying processes. Specifically, this chapter discusses the material removal applications of lasers. Drilling, grooving, cutting, three-dimensional machining operations such as lathe and milling operations, micro machining and laser assisted machining processes are the extended applications of lasers in LBM [3].

#### **6.1 Drilling using LBM**

One of the major advantages in drilling using lasers compared to conventional machining process is the aspect ratio (max 1:20) and small size of the hole drilled. Both continuous and pulse laser are used for drilling operations in which pulsed laser gives lesser plasma generation. The types of drilling operations that can be performed using LBM are single-pulsed drilling, percussion drilling, trepanning and helical drilling. When laser beam is focused into the material, the temperature is created by absorbing the photons. The material melts and vaporizes when the temperature exceeds the melting temperature of the material. If the radiation of laser is set lesser than particular threshold (106 W/cm2 for steels), the material melts but not vaporizes and using a jet of gas the molten material is ejected [13]. The single pulse drilling process makes either through or blind holes with less than 1:15 aspect ratio. This is a rapid drilling process mainly suitable where production rate is more important than quality. Single pulse drilling is mostly adapted in automotive industry for processing connecting rods and filters. Percussion drilling uses pulsed-lasers' focus on the same spot to produce a hole while maintaining a balance between throughput and quality. Due to major advantages like its precision and quick processing capability, percussion drilling is adapted in making holes in the blades of turbine-airfoil. Though it has major advantages, there are drawbacks reported such as dross, spatter, and tapering.

Trepanning technique is another hole making technique where the material removal is performed on the circumference of any circle to make holes of higher diameters. It is considered to be a standard technique for making holes around 500 micrometers diameter. The nanosecond pulsed laser source is utilized for material removal around the circumference hence the drawbacks of percussion drilling remains in this application also. Trepanning technique reduces the taper effect and produces more jagged edge quality. To overcome the drawbacks of trepanning a relatively new technique called helical drilling is introduced. Helical drilling follows multitude ablation steps. The advantages of helical drilling over trepanning using percussion drilling are improved circularity of drilled holes, minimized loads on opposite walls and more importantly reduced recast layers or sometimes completely

**97**

**Figure 13.**

*LBM for cutting operation.*

*Laser Machining*

rial as shown in **Figure 12**.

**6.2 Cutting using LBM**

*Schematic of laser drilling.*

**Figure 12.**

*DOI: http://dx.doi.org/10.5772/intechopen.93779*

avoided. Helical drilling is more preferred in the case of laser beam diameter is very near to helical diameter at focus point. Energy balance is important in laser drilling among the energy released by laser beam, energy absorbed by material, energy lost to the surrounding and the energy utilized for melting (phase changing) the mate-

Cutting is an essential operation in any material removal processes. A relative

dimensional working plane where the material removal takes place. During relative motion of laser beam and work piece, a kerf is produced which removes the material in its path. Complex two-dimensional shapes can be cut from the flat work piece

motion between work piece and the laser beam is required to produce a two-

*Laser Machining DOI: http://dx.doi.org/10.5772/intechopen.93779*

*Practical Applications of Laser Ablation*

applications of lasers in LBM [3].

laser is set lesser than particular threshold (106 W/cm2

reported such as dross, spatter, and tapering.

**6.1 Drilling using LBM**

**6. Applications**

resulting in a creation of two-dimensional surface as shown in **Figure 11**. Twodimensional LBM is most suitable for cutting operations. Three-dimensional LBM uses two or more sources of laser beams. Each laser beam forms two-dimensional surfaces according to their relative motion with the work piece. When the surfaces formed by each laser beams intersects a three-dimensional space is created that defines the shape of material to be removed. Three-dimensional LBM process is generally used for milling process. For better understanding of different types of

In general, the use of lasers found in many applications includes chemical, biochemical, optics, medical, military operations, polymer sciences, nuclear physics [8–12] and so on. In manufacturing, lasers are successfully applied for material removal, metal joining, cladding and alloying processes. Specifically, this chapter discusses the material removal applications of lasers. Drilling, grooving, cutting, three-dimensional machining operations such as lathe and milling operations, micro machining and laser assisted machining processes are the extended

One of the major advantages in drilling using lasers compared to conventional machining process is the aspect ratio (max 1:20) and small size of the hole drilled. Both continuous and pulse laser are used for drilling operations in which pulsed laser gives lesser plasma generation. The types of drilling operations that can be performed using LBM are single-pulsed drilling, percussion drilling, trepanning and helical drilling. When laser beam is focused into the material, the temperature is created by absorbing the photons. The material melts and vaporizes when the temperature exceeds the melting temperature of the material. If the radiation of

melts but not vaporizes and using a jet of gas the molten material is ejected [13]. The single pulse drilling process makes either through or blind holes with less than 1:15 aspect ratio. This is a rapid drilling process mainly suitable where production rate is more important than quality. Single pulse drilling is mostly adapted in automotive industry for processing connecting rods and filters. Percussion drilling uses pulsed-lasers' focus on the same spot to produce a hole while maintaining a balance between throughput and quality. Due to major advantages like its precision and quick processing capability, percussion drilling is adapted in making holes in the blades of turbine-airfoil. Though it has major advantages, there are drawbacks

Trepanning technique is another hole making technique where the material removal is performed on the circumference of any circle to make holes of higher diameters. It is considered to be a standard technique for making holes around 500 micrometers diameter. The nanosecond pulsed laser source is utilized for material removal around the circumference hence the drawbacks of percussion drilling remains in this application also. Trepanning technique reduces the taper effect and produces more jagged edge quality. To overcome the drawbacks of trepanning a relatively new technique called helical drilling is introduced. Helical drilling follows multitude ablation steps. The advantages of helical drilling over trepanning using percussion drilling are improved circularity of drilled holes, minimized loads on opposite walls and more importantly reduced recast layers or sometimes completely

for steels), the material

LBM processes a schematic representation is given in **Figure 11** [7].

**96**

#### **Figure 12.** *Schematic of laser drilling.*

avoided. Helical drilling is more preferred in the case of laser beam diameter is very near to helical diameter at focus point. Energy balance is important in laser drilling among the energy released by laser beam, energy absorbed by material, energy lost to the surrounding and the energy utilized for melting (phase changing) the material as shown in **Figure 12**.
