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Remanufacturing and Advanced Machining
• Universality of the process means AWJ machining applicability to virtually
any material. In the case of composites or multicomponent sandwich-like
structures, the water jet does not cause disruption of the original structure
and thus initial properties of a material are retained after AWJ machining.
• Ability to reproduce complex profiles and shapes at any declination angle.
In this respect, the water jet can be compared with a point-cutting tool with
all its benefits. Especially while machining a brittle material like glass,
AWJ allows for producing shapes unachievable by other techniques. While
straight cutting of glass with diamond is more efficient, no other cutting
technology can produce such a complex shape out of glass.
• Good surface quality of roughness Ra between 0.5 and 1.5 μm is achieved,
so that additional finishing is not necessary in many cases.
• Technological flexibility of the process is due to the unique properties of the
cutting tool. It is not worn, so there is no need to replace or sharpen it, tool
load on the workpiece is minimal, backward pressure is absent, since there
is no direct contact between the cutting head and the workpiece. The same
tool can perform different technological operations and its low tangential
force allows for avoiding fixation of the workpiece. It is possible to use the
waterjet cutting head even 200 m away from the pump, and one pump can
feed two or more cutting heads operating either on the same table or on different tables. AWJ machining can be performed in various conditions, e.g.,
at a height of hundreds of meters and even under water.
• Economic benefits can be derived from the high cutting speed. The operation can be started at any point on the workpiece surface with no need for
pre-drilling. The small width of a slot after cutting indicates savings of the
cut material. Added to all that, water consumption is rather small despite
high pressure and is kept in the range of 3–4 l/min.
• Automation of the process is very easy, digital control can be applied
together with optical inspection devices, so that AWJ can be realized by
6-axis full robots.
• Availability of the process is easy due to the simple and relatively cheap
media like water and quartz sand.
• Safety conditions are assured because no heat is accumulated during AWJ
machining, with no danger of fire or explosion. There is no radiation, dust,
or smoke either, and the noise level is between 85 and 95 dB.
1.12.4 limiTaTions and environmenTal imPacT of awj machining
Though well established, the AWJ machining process has some limitations that prevent the wider industrial application of this method. These include generation of a
higher volume of secondary wastage following machining and of heat developed
in the primary impact zone, abrasive contamination, taper and striation formation,
rough surface, and low energy-transfer efficiency from the nozzle to the workpiece,
which causes a low depth of penetration and low material removal rate (Natarajan
et al., 2020). Additional limitations are listed by Korzhov (2006):
Remanufacturing and Advanced Machining
• Universality of the process means AWJ machining applicability to virtually
any material. In the case of composites or multicomponent sandwich-like
structures, the water jet does not cause disruption of the original structure
and thus initial properties of a material are retained after AWJ machining.
• Ability to reproduce complex profiles and shapes at any declination angle.
In this respect, the water jet can be compared with a point-cutting tool with
all its benefits. Especially while machining a brittle material like glass,
AWJ allows for producing shapes unachievable by other techniques. While
straight cutting of glass with diamond is more efficient, no other cutting
technology can produce such a complex shape out of glass.
• Good surface quality of roughness Ra between 0.5 and 1.5 μm is achieved,
so that additional finishing is not necessary in many cases.
• Technological flexibility of the process is due to the unique properties of the
cutting tool. It is not worn, so there is no need to replace or sharpen it, tool
load on the workpiece is minimal, backward pressure is absent, since there
is no direct contact between the cutting head and the workpiece. The same
tool can perform different technological operations and its low tangential
force allows for avoiding fixation of the workpiece. It is possible to use the
waterjet cutting head even 200 m away from the pump, and one pump can
feed two or more cutting heads operating either on the same table or on different tables. AWJ machining can be performed in various conditions, e.g.,
at a height of hundreds of meters and even under water.
• Economic benefits can be derived from the high cutting speed. The operation can be started at any point on the workpiece surface with no need for
pre-drilling. The small width of a slot after cutting indicates savings of the
cut material. Added to all that, water consumption is rather small despite
high pressure and is kept in the range of 3–4 l/min.
• Automation of the process is very easy, digital control can be applied
together with optical inspection devices, so that AWJ can be realized by
6-axis full robots.
• Availability of the process is easy due to the simple and relatively cheap
media like water and quartz sand.
• Safety conditions are assured because no heat is accumulated during AWJ
machining, with no danger of fire or explosion. There is no radiation, dust,
or smoke either, and the noise level is between 85 and 95 dB.
1.12.4 limiTaTions and environmenTal imPacT of awj machining
Though well established, the AWJ machining process has some limitations that prevent the wider industrial application of this method. These include generation of a
higher volume of secondary wastage following machining and of heat developed
in the primary impact zone, abrasive contamination, taper and striation formation,
rough surface, and low energy-transfer efficiency from the nozzle to the workpiece,
which causes a low depth of penetration and low material removal rate (Natarajan
et al., 2020). Additional limitations are listed by Korzhov (2006):