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Contemporary Machining Processes
• Plasma methods involve relatively simple and easily up-scalable apparatus,
which enables successive cleaning, activation, and coating deposition without any hazardous handling, simply by changing the processing gas.
• Treatment times (some tens of minutes at most) and numbers of processing steps are also significantly reduced, since components can be exploited
directly after the treatment. Thus, plasma processes are economically
attractive.
• In the area of nanomaterial plasma surface treatment, especially in nanocrystal plasma synthesis, the resistance of particles to aggregation due to a
high degree of surface charging is a very important benefit.
Given the enormous variety of plasma processing and plasma-assisted machining
techniques, it seems convenient to follow a classification of methods according to
their final effect (Dragobetsky et al., 2012):
1. Material removal methods
(a) cutting of pre-fabricated material
(b) shaping of workpiece
2. Joining processes
(a) plasma welding
(b) plasma microwelding
3. Additive methods
(a) plasma cladding
(b) plasma sputtering
According to the classification provided by Quintino (2014), the third category can
be treated as “surface engineering,” since this term covers a diversity of technologies
that alter the chemistry and properties of a thin surface layer of the substrate, including cladding processes which produce thick coatings. From this point of view, there
are several additional methods of surface treatment with plasma aimed at modifying
chemical and physical properties of a surface, such as cleaning, activation, etching, coating, plasma ashing, plasma electrolytic oxidation, plasma functionalization,
plasma polymerization, and plasma modification of surface layer.
Plasma arc cutting (PAC) is a nontraditional metal removal process which
employs a high-temperature and high-velocity constricted arc. The energy content
of the plasma is focused through a nozzle with an increased momentum and the
intense heat melts and partially vaporizes workpiece material. A power density of
10 8 W/m 2 can be generated, which can vaporize almost all solid materials, allowing
to cut stainless steel, manganese steel, high-speed steel, cast iron, and hardened
alloys at greater speeds. Moreover, high tolerance PAC effectively cuts titanium
sheets and the quality characteristics are better with oxygen as plasma gas than
nitrogen because of the oxidation process (Adalarasan et al., 2015). In plasma arc
cutting, an electric arc is established between a workpiece (cathode) and a tungsten
anode with characteristics of ca. 5,000 A/cm 2 , 100 A, and 100 V. The arc causes
a localized melting of the workpiece and a gas flux removes the liquid phase of
Contemporary Machining Processes
• Plasma methods involve relatively simple and easily up-scalable apparatus,
which enables successive cleaning, activation, and coating deposition without any hazardous handling, simply by changing the processing gas.
• Treatment times (some tens of minutes at most) and numbers of processing steps are also significantly reduced, since components can be exploited
directly after the treatment. Thus, plasma processes are economically
attractive.
• In the area of nanomaterial plasma surface treatment, especially in nanocrystal plasma synthesis, the resistance of particles to aggregation due to a
high degree of surface charging is a very important benefit.
Given the enormous variety of plasma processing and plasma-assisted machining
techniques, it seems convenient to follow a classification of methods according to
their final effect (Dragobetsky et al., 2012):
1. Material removal methods
(a) cutting of pre-fabricated material
(b) shaping of workpiece
2. Joining processes
(a) plasma welding
(b) plasma microwelding
3. Additive methods
(a) plasma cladding
(b) plasma sputtering
According to the classification provided by Quintino (2014), the third category can
be treated as “surface engineering,” since this term covers a diversity of technologies
that alter the chemistry and properties of a thin surface layer of the substrate, including cladding processes which produce thick coatings. From this point of view, there
are several additional methods of surface treatment with plasma aimed at modifying
chemical and physical properties of a surface, such as cleaning, activation, etching, coating, plasma ashing, plasma electrolytic oxidation, plasma functionalization,
plasma polymerization, and plasma modification of surface layer.
Plasma arc cutting (PAC) is a nontraditional metal removal process which
employs a high-temperature and high-velocity constricted arc. The energy content
of the plasma is focused through a nozzle with an increased momentum and the
intense heat melts and partially vaporizes workpiece material. A power density of
10 8 W/m 2 can be generated, which can vaporize almost all solid materials, allowing
to cut stainless steel, manganese steel, high-speed steel, cast iron, and hardened
alloys at greater speeds. Moreover, high tolerance PAC effectively cuts titanium
sheets and the quality characteristics are better with oxygen as plasma gas than
nitrogen because of the oxidation process (Adalarasan et al., 2015). In plasma arc
cutting, an electric arc is established between a workpiece (cathode) and a tungsten
anode with characteristics of ca. 5,000 A/cm 2 , 100 A, and 100 V. The arc causes
a localized melting of the workpiece and a gas flux removes the liquid phase of