65
Contemporary Machining Processes
such wide possibilities, PEO is a promising method able to produce porous, high
crystalline, and about 1–100 μm thick oxide coatings. As-obtained coatings have
demonstrated good adhesion to the substrate, high surface microhardness, high-temperature shock tolerance, significant resistance to corrosion and wear, and a significant insulation resistance in working conditions (Attarzadeh et al., 2021).
Plasma beam can be used for polishing of some metals and alloys. Deng et al.
(2018) propose a method of micro-beam plasma polishing using a modified microplasma welding machine. Their plasma was operated in a continuous-wave mode,
with a maximum electric current of 11 A. The micro-plasma torch consisted of a
tungsten electrode bur (d = 1.0 mm), a nozzle (d = 1.2 mm), a plasma protective
cap (d = 7 mm), and a pipe liner for centering. Argon was used for the purposes
of both ionization and protection of alloy steel from oxidization, at a constant gas
flow rate of 6 L/min for protection and a maximum of 0.5 L/min for ionization. The
authors concluded that micro-beam plasma polishing could reduce surface altitude
differences by 91% and surface roughness by 88%, e.g., from Ra = 4.07 μm to Ra =
0.46 μm. Additionally, micro-beam plasma polishing provided some improvement to
the hardness of tested steels and alloys without surface impurity defects.
In remanufacturing processes, micro-plasma transferred arc (μPTA) is one of
the latest options. It can be applied to remanufacturing of die and mold surfaces in a
near-millimeter range in order to extend their usage and become a viable economical
and cleaner methodology for potential industrial applications (Jhavar et al., 2016).
μPTA deposition is advantageous in terms of lower initial setup and running costs
with adequate quality of repaired components. A comparison of power consumption per unit weight of filler material and consumption rate of filler material for
material deposition using laser between gas metal arc welding and μPTA sources
demonstrated that μPTA is a successful alternative for remanufacturing of tool steel
surfaces.
Plasma can also be employed in methods of plasma-enhanced chemical vapor
deposition. The chemical reactions required for the deposition are facilitated by the
presence of a plasma arc containing hot electrons. Following deposition of a vapor
phase on the substrate, a coating is produced out of metals, ceramics, and carbonbased nanomaterials (Biesuz et al., 2021).
1.12 WATERJET MACHINING
New materials, such as high-temperature alloys, high-performance ceramics, metalmatrix composites, and fiber-reinforced plastics, are examples of materials which
have to be machined with adapted conventional machining techniques or by means of
new machining processes due to their wear resistance and high strength maintained
kept even in aggressive environments or at high temperatures (König et al., 1990).
1.12.1 waTerjeT machining PrinciPle and influencing facTors
Waterjet machining can be considered a cold cutting process, because it involves the
removal of material without releasing heat. This revolutionary technology is able to
Contemporary Machining Processes
such wide possibilities, PEO is a promising method able to produce porous, high
crystalline, and about 1–100 μm thick oxide coatings. As-obtained coatings have
demonstrated good adhesion to the substrate, high surface microhardness, high-temperature shock tolerance, significant resistance to corrosion and wear, and a significant insulation resistance in working conditions (Attarzadeh et al., 2021).
Plasma beam can be used for polishing of some metals and alloys. Deng et al.
(2018) propose a method of micro-beam plasma polishing using a modified microplasma welding machine. Their plasma was operated in a continuous-wave mode,
with a maximum electric current of 11 A. The micro-plasma torch consisted of a
tungsten electrode bur (d = 1.0 mm), a nozzle (d = 1.2 mm), a plasma protective
cap (d = 7 mm), and a pipe liner for centering. Argon was used for the purposes
of both ionization and protection of alloy steel from oxidization, at a constant gas
flow rate of 6 L/min for protection and a maximum of 0.5 L/min for ionization. The
authors concluded that micro-beam plasma polishing could reduce surface altitude
differences by 91% and surface roughness by 88%, e.g., from Ra = 4.07 μm to Ra =
0.46 μm. Additionally, micro-beam plasma polishing provided some improvement to
the hardness of tested steels and alloys without surface impurity defects.
In remanufacturing processes, micro-plasma transferred arc (μPTA) is one of
the latest options. It can be applied to remanufacturing of die and mold surfaces in a
near-millimeter range in order to extend their usage and become a viable economical
and cleaner methodology for potential industrial applications (Jhavar et al., 2016).
μPTA deposition is advantageous in terms of lower initial setup and running costs
with adequate quality of repaired components. A comparison of power consumption per unit weight of filler material and consumption rate of filler material for
material deposition using laser between gas metal arc welding and μPTA sources
demonstrated that μPTA is a successful alternative for remanufacturing of tool steel
surfaces.
Plasma can also be employed in methods of plasma-enhanced chemical vapor
deposition. The chemical reactions required for the deposition are facilitated by the
presence of a plasma arc containing hot electrons. Following deposition of a vapor
phase on the substrate, a coating is produced out of metals, ceramics, and carbonbased nanomaterials (Biesuz et al., 2021).
1.12 WATERJET MACHINING
New materials, such as high-temperature alloys, high-performance ceramics, metalmatrix composites, and fiber-reinforced plastics, are examples of materials which
have to be machined with adapted conventional machining techniques or by means of
new machining processes due to their wear resistance and high strength maintained
kept even in aggressive environments or at high temperatures (König et al., 1990).
1.12.1 waTerjeT machining PrinciPle and influencing facTors
Waterjet machining can be considered a cold cutting process, because it involves the
removal of material without releasing heat. This revolutionary technology is able to