**4.3 Subtractive and transformative manufacturing processes**

## *4.3.1 Thermally enhanced mechanical machining*

In the process of thermally enhanced mechanical machining externally heat sources is applied to heat the metal locally in front of the cutting tool. The heating effect changes the microstructure of the workpiece and it softened the material which allowed reduction in hardness, cutting forces and tool wear during material removing process on conventional machines. The frequently used external heat sources are laser beam and plasma. Laser assisted mechanical machining has been considered as an alternative process for machining of high-strength materials, such as high-temperature alloys, metal matrix composites, ceramics [18–21].

**Figure 11.** *Polymer Injection Forming process sequence [17].*

stage after part material cured it removed from the mold and finishing operation take place, for example removal of gates and runners. An alternative method also can be applicable in which the mold material is used as a fixturing during finishing

Klelkar et al. developed a re-configurable molding process by using movable pins, as shown in **Figure 10**, to generate a cavity in the mold, the process has limitation as a part surface is only approximated. According to the change of product design the pins can be re-positioned, and a required mold cavity can be produced. Kelkar and Koc introduced multiaxis machining in re-configurable mold tooling. Multi-axis machining was used to improve the surface accuracy of the part after a part is molded. The both process was carried on same setup and make it

operations and then it can be remove in later stage [11–14].

*Computational Optimization Techniques and Applications*

*4.1.4 Injection molding and machining*

**Figure 9.**

*SDM and machining.*

suitable for a batch production [15, 16].

**Figure 10.**

**102**

*Injectioun molding and machining.*

## *4.3.2 Grinding and hardening*

The grind-hardening process shown in **Figure 12** used to surface harden steel parts. This process is using greater depth of cuts, up to 1 mm, and slower workpiece speeds. Rotating grinding wheel generate a heat at contact by which the surface temperature of material raised above that of authentication. Also by introducing self-quenching for heat dissipation by using coolant, martensitic phase transformation takes place [22, 23].

the two sheets at the interface dissolves polymer chains. After a while as solvent evaporates or absorbed it result in an interface weld and a solid part, which allows new molecular bonds between the two sheets to be established. This process is very rapid, and in practical, the platen apply pressure for only 5 seconds. Then by a CNC milling machine the cross-sectional contour cut down with a small diameter end mill cutter. As the machined sheets are preassembled prior to machining, process does not have any requirement of post assembly or special registration. Final product is completed after every layers has been added to the assembly and machined, the part can be removed from the build platform for the post processing as per the

*A Review on Advanced Manufacturing Techniques and Their Applications*

Plasma laser deposition manufacturing working principle is shown in **Figure 14**. Powder is continuously feeding by control system into molten pool where powder is melted due to the focused laser beam and it result in re-solidification. The coatings thickness and 3D CAD model part must be predefined. To reduce oxidation, the whole operation is carried out under inert gas argon environment. The worktable is controlled by the control system. The material is deposited side by side with a defined amount of overlap. After deposition of an entire coating layer, the beam height of laser and plasma considerably keep away from the surface. The variables in the process such as power of combine plasma and laser beam, velocity of beam movement, feeding rate of material are controlled as per requirement of part to manufacture a final product. This proposed PLDM process offers several advantages over conventional sur-

i. The traditional spray coating process can only used for thin coatings; The proposed PLDM process can allow to deposit thick layer coatings and it surfaces coating thickness can be controlled according to their requirements.

ii. The PLDM also allows material with a higher melting point such as alloys and refractory materials to directly fabricating different materials coatings.

iii. The PLDM process also offers comparatively high-quality microstructure

requirement [24, 25].

**4.5 Additive manufacturing processes**

*DOI: http://dx.doi.org/10.5772/intechopen.97702*

*4.5.1 Melting deposited material*

face coatings techniques [26, 27]:

**Figure 14.**

**105**

*Plasma laser deposition manufacturing.*

and other mechanical characteristics.

## **4.4 Subtractive joining process**

A configuration of schematic diagram of Solvent Welding Freeform Fabrication Technique (SWIFT) process is shown in **Figure 13**. In initial stage a standard size solvent weldable thermoplastic sheets placed loaded into a sheet feeder. The most frequently used solvent weldable thermoplastics materials are polystyrene, polycarbonate, PVC, and ABS. A pair of pinch rollers are used to fed sheets forward. Forwared sheet passes through a solvent masking which assist to prevent unwanted welding in desired areas. Solvent has been applied to the underside of the sheet at solvent masking station. Sheets are feeding continuous until it is positioned over the build platform. A platen is used to apply pressure on the sheet which is positioned over the stack of previously assembled sheets. In the process the new sheet placed on the top surface of the previously applied sheet, then the applied solvent between

**Figure 12.** *Grind hardning process.*

**Figure 13.** *Swift process configuration.*

#### *A Review on Advanced Manufacturing Techniques and Their Applications DOI: http://dx.doi.org/10.5772/intechopen.97702*

the two sheets at the interface dissolves polymer chains. After a while as solvent evaporates or absorbed it result in an interface weld and a solid part, which allows new molecular bonds between the two sheets to be established. This process is very rapid, and in practical, the platen apply pressure for only 5 seconds. Then by a CNC milling machine the cross-sectional contour cut down with a small diameter end mill cutter. As the machined sheets are preassembled prior to machining, process does not have any requirement of post assembly or special registration. Final product is completed after every layers has been added to the assembly and machined, the part can be removed from the build platform for the post processing as per the requirement [24, 25].
