**6.2 Cutting using LBM**

Cutting is an essential operation in any material removal processes. A relative motion between work piece and the laser beam is required to produce a twodimensional 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

**Figure 13.** *LBM for cutting operation.*

**Figure 14.**

*Three-dimensional LBM for (a) lathe operation and (b) milling operation.*

materials where mechanism of material removal is similar to drilling operation. In contrast to the drilling process, the erosion front is located at the front of line of laser beam as shown in **Figure 13**. However, the temperature field and erosion front is fixed based on the coordinate moves along with produced laser source that ensures steady state process. The erosion front molten material is flushed away using a gas jet during the cutting process.

## **6.3 Three-dimensional LBM**

Three-dimensional LBM uses two or more number of laser beams simultaneously focused to obtain an intersected volume for material removal. To precisely create such volumes with relative motions, highly accurate optical manipulating systems are therefore necessary. Recent systems equipped with optical scanning systems have high level of control over the motion of laser beams which enables efficient and effective machining operations. The material removal using these tools is referred as 3-dimensional (3D) laser material processing. In general, the 3D laser material processing is grouped into various categories such as laser beams along with 3D LBM, 5-axis heads along with 3D processing workstation and 3D remote laser processing. **Figure 14** illustrate the graphical picture of two-beam laser machining processes for lathe and milling operations. Each beam creates a groove like volume of material removal when they intersect with some incidence angle. The incidence angle may be changed and dynamically varied along with relative motion to get intricate shapes of machining.

LBM is successfully adapted in micromachining field due to its high flexibility to automation and high degree of radiance. Laser beam micromachining is capable of producing parts with sizes ranging from micro to sub-micro scales. It usually employs the pulsed lasers with an average power of less than 1 kW. The pulses of femtosecond duration are widely used for micromachining. Micromachining can be performed on wide range of materials such as metals, glasses, diamond and other difficult to machining materials. Laser-assisted manufacturing (LAM) is another technique helps to enhance the maximum productivity, quality with minimized machine tool vibrations, machining forces and tool wear. LAM is also an effective technique to machine brittle materials without cracks and failure. This hybrid machining process, laser beam is focused on the work piece just before the cutting tool engages. Scanning of laser initially heats up the work therefore helps in plastic deformation rather than brittle deformation during machining. The LAM processes are suitable for brittle and hard type of material such as ceramics, nickel alloys and the higher amount of silicon element material.

**99**

also has several limitations such as,

*Laser Machining*

**7. Advantages**

machining.

**8. Limitations**

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

machining processes due to many advantages as follow:

therefore post processing can be eliminated.

no requirement of chemicals or solvents for machining.

damages, vibrations, frequent tooling requirements.

ity and conductivity can be machined.

• Degree of accuracy in machining complex geometry is high.

LBM is an excellent manufacturing technique to process wide ranges of difficult to machine materials especially ceramics and advanced composite materials. LBM technique is capable of machining intricate shapes that cannot be reached or processed by conventional machining processes. LBM is an alternate to conventional

• Due to precise machining capability, LBM can produce excellent surface finish

• LBM is a clean manufacturing technique due to less environment pollution and

• LBM can be easily automated for higher productivity and to achieve high speed

• It uses no cutting tool therefore no cutting forces involved during machining. This phenomenon helps to avoid heavy construction of machine tools, physical

• LBM depends on thermal and few optical properties of work material rather than mechanical properties such as hardness and brittleness. As a result, most of the materials with any degree of mechanical properties with lower diffusiv-

• Wide range of materials from plastics to diamond can be machined.

• Machining micro features with large aspect ratio is possible with LBM.

There are many issues and limitations associated with the aforementioned LBM technique. The major issues are produced accuracy, achieved surface quality and rate of material removal. The erosion front is the main factor decides the amount of material removal in LBM technique. In one-dimensional machining, the speed of propagation in erosion front in the straight line decides the rate of material removal. In another hand, the scanning speed plays a significant role in metal removal during the two-dimensional machining processes. Similarly, the laser scanning speed is produced the intersecting surfaces for volume formation and the decisive factor for material removal rate during the 3D machining processes. Controlling the LBM parameters for a balanced and effective machining is a real challenge faced by industries. Secondly, the dimensional accuracy is affected by the kerf shape of laser which leads to tapered holes instead of narrow holes. Surface quality is the other important aspect of machining, which is measured by surface roughness, formation of dross and the HAZ. Since LBM is completely thermal based machining process it

• Residual stresses caused due to HAZ are very less in LBM.
