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Remanufacturing and Advanced Machining
The main technical challenges of LCR include:
• Low repeatability and quality of repair layers
• It is difficult to achieve adaptive control
• Difficult and expensive post-process inspection
• Accumulative error
Through optimization of the laser cladding parameters, it is possible to produce
smooth, crack-free, and low porosity rate Ni60A clad layers which are metallurgically bonded to a 45 steel substrate (Wu, Li et al., 2019). The authors reported that
linear energy density served to identify a threshold for the elimination of large
porosity and statistical analysis helped to optimize process parameters. It was
demonstrated that powder feed rate in the coating process was the most significant
parameter considering the porosity area and cracks were effectively eliminated by
a combination of preheating to 300°C and placing an insulated plank under the
substrate. Coating of a crack-free large and low porosity of 0.027% were obtained
successfully. Its average microhardness was about 2.7 times higher than that of the
substrate.
In the case of Inconel 718 and other nickel-based superalloys that are generally used in aerospace, gas turbines, turbochargers, etc., directed energy deposition
techniques provide a cost-effective solution for repairing highly valuable components and reduce the turnaround time for fabrication and replacement with a new
component (Shrivastava et al., 2021). However, component parts deposited near the
edges show the presence of pores which affect the strength and functionality of the
component. Moreover, alloy microstructure is sensitive to the process parameters
causing considerable variations in the microstructure of deposition layers in the +z
direction.
The following can be mentioned among recently reported achievements of LCR:
repair of turbine blades from Ni-based superalloy CMSX-4 through the formation
of monocrystalline CMSX-4, repair of tools used in soil cultivation to enhance wear
resistance due to formation of intermetallic compounds Stellite-6/WC on a B27
boron steel substrate, upgrades to a barrel-screw system Ni40 and Ni60 on C60 steel
used in plastic injection molding to improve microhardness, repair of molds and dies
employed in hot and cold working through cladding CPM9V steel on an H13 tool
steel substrate, repair of railway wheels to increase the hardness of clad materials
and reduce wear, or replacement of natural bone, possible through cladding titanium
hydroxylapatite on a nitinol substrate, since hydroxyapatite coating reduces nickel
release (Siddiqui and Dubey, 2021).
Environmental impacts of remanufacturing can be understood in the example of a
cast iron cylinder head block. The analysis performed by Liu et al. (2016) compared
remanufacturing through laser cladding with new cylinder head block manufacturing. Considering resource and energy consumptions of these processes and based on
six selected environmental impact categories, it was demonstrated that cylinder head
remanufacturing by laser cladding would achieve large environmental benefits, cutting environment impact over the entire life cycle by 63.8% on average.
Remanufacturing and Advanced Machining
The main technical challenges of LCR include:
• Low repeatability and quality of repair layers
• It is difficult to achieve adaptive control
• Difficult and expensive post-process inspection
• Accumulative error
Through optimization of the laser cladding parameters, it is possible to produce
smooth, crack-free, and low porosity rate Ni60A clad layers which are metallurgically bonded to a 45 steel substrate (Wu, Li et al., 2019). The authors reported that
linear energy density served to identify a threshold for the elimination of large
porosity and statistical analysis helped to optimize process parameters. It was
demonstrated that powder feed rate in the coating process was the most significant
parameter considering the porosity area and cracks were effectively eliminated by
a combination of preheating to 300°C and placing an insulated plank under the
substrate. Coating of a crack-free large and low porosity of 0.027% were obtained
successfully. Its average microhardness was about 2.7 times higher than that of the
substrate.
In the case of Inconel 718 and other nickel-based superalloys that are generally used in aerospace, gas turbines, turbochargers, etc., directed energy deposition
techniques provide a cost-effective solution for repairing highly valuable components and reduce the turnaround time for fabrication and replacement with a new
component (Shrivastava et al., 2021). However, component parts deposited near the
edges show the presence of pores which affect the strength and functionality of the
component. Moreover, alloy microstructure is sensitive to the process parameters
causing considerable variations in the microstructure of deposition layers in the +z
direction.
The following can be mentioned among recently reported achievements of LCR:
repair of turbine blades from Ni-based superalloy CMSX-4 through the formation
of monocrystalline CMSX-4, repair of tools used in soil cultivation to enhance wear
resistance due to formation of intermetallic compounds Stellite-6/WC on a B27
boron steel substrate, upgrades to a barrel-screw system Ni40 and Ni60 on C60 steel
used in plastic injection molding to improve microhardness, repair of molds and dies
employed in hot and cold working through cladding CPM9V steel on an H13 tool
steel substrate, repair of railway wheels to increase the hardness of clad materials
and reduce wear, or replacement of natural bone, possible through cladding titanium
hydroxylapatite on a nitinol substrate, since hydroxyapatite coating reduces nickel
release (Siddiqui and Dubey, 2021).
Environmental impacts of remanufacturing can be understood in the example of a
cast iron cylinder head block. The analysis performed by Liu et al. (2016) compared
remanufacturing through laser cladding with new cylinder head block manufacturing. Considering resource and energy consumptions of these processes and based on
six selected environmental impact categories, it was demonstrated that cylinder head
remanufacturing by laser cladding would achieve large environmental benefits, cutting environment impact over the entire life cycle by 63.8% on average.