5
Contemporary Machining Processes
Open‑loop recycling: conversion of materials from one or more products into
a new product, involving degradation in inherent material properties (downcycling). In open-loop recycling, inherent properties of a recycled material
differ from those of the virgin material in such a way that it is only usable
for other product applications, substituting other materials.
Apart from reuse, remanufacturing, and recycling, three more EoL strategies
can be found in the literature (Fegade et al., 2015):
Reconditioning: it is a process of restoring parts or components to a functional
state but not above original specifications by resurfacing, repainting, etc.
Refurbishment: part or components are cleaned and repaired for reuse or
resell.
Component Cannibalization: limited number of components are extracted
from product and used to repair or rebuild another unit of same product.
Apart from benefiting the environment and ecosystem, the remanufacturing strategy
has positively affected socioeconomies of various countries (Wahab et al., 2018). Being
one of the EoL recovery strategies, remanufacturing is widely implemented in the transportation industry, namely aircraft, automotive, rail, and marine sectors. To date, the
world’s largest sector that benefits from remanufacturing is the automobile parts industry. In the aerospace/aircraft industry, original equipment manufacturers are involved
in the remanufacturing process to a very great degree. It is known that many assemblies and structures such as engines, avionics, landing gear, and cabin interiors undergo
remanufacturing procedures at least once. It is reported that some high-performance
products such as Caterpillar’s heavy-duty engines can be remanufactured as many as
six times and serve seven use cycles. In the marine industry, intensity of remanufacturing is low compared to other transportation sectors such as aerospace, automotive, and
rail. For example, marine components such as engines, propeller shafts, compressors,
and pumps have been successfully remanufactured in many countries, but remanufacturing of large structures such as hull and vessels has not been reported thus far. Today,
with a large number of ships approaching EoL, the share of remanufacturing should be
increasing due to its positive impact on the environment (Wahab et al., 2018).
Used-up EoL products or components received for restoration are of a significant
uncertainty and variability when it comes to their quantity and quality. In order
to determine key characteristics of remanufactured products, the following steps
should be undertaken (Lahrour and Brissaud, 2018):
1. Determining steps of the remanufacturing process
2. Proposing a framework of additive remanufacturing
3. Identifying key steps and characteristics of products that might be remanufactured by a chosen process
Remanufacturability evaluation should consider also effects of fatigue failure on the
model of the remanufacturing critical threshold. Such models were analyzed based on
a qualitative relationship between the fatigue life and remanufacturing requirements
and compared with existing remanufacturing evaluation systems as reference, proposing two new remanufacturability evaluation indexes (Wang, Yu et al., 2020).
Contemporary Machining Processes
Open‑loop recycling: conversion of materials from one or more products into
a new product, involving degradation in inherent material properties (downcycling). In open-loop recycling, inherent properties of a recycled material
differ from those of the virgin material in such a way that it is only usable
for other product applications, substituting other materials.
Apart from reuse, remanufacturing, and recycling, three more EoL strategies
can be found in the literature (Fegade et al., 2015):
Reconditioning: it is a process of restoring parts or components to a functional
state but not above original specifications by resurfacing, repainting, etc.
Refurbishment: part or components are cleaned and repaired for reuse or
resell.
Component Cannibalization: limited number of components are extracted
from product and used to repair or rebuild another unit of same product.
Apart from benefiting the environment and ecosystem, the remanufacturing strategy
has positively affected socioeconomies of various countries (Wahab et al., 2018). Being
one of the EoL recovery strategies, remanufacturing is widely implemented in the transportation industry, namely aircraft, automotive, rail, and marine sectors. To date, the
world’s largest sector that benefits from remanufacturing is the automobile parts industry. In the aerospace/aircraft industry, original equipment manufacturers are involved
in the remanufacturing process to a very great degree. It is known that many assemblies and structures such as engines, avionics, landing gear, and cabin interiors undergo
remanufacturing procedures at least once. It is reported that some high-performance
products such as Caterpillar’s heavy-duty engines can be remanufactured as many as
six times and serve seven use cycles. In the marine industry, intensity of remanufacturing is low compared to other transportation sectors such as aerospace, automotive, and
rail. For example, marine components such as engines, propeller shafts, compressors,
and pumps have been successfully remanufactured in many countries, but remanufacturing of large structures such as hull and vessels has not been reported thus far. Today,
with a large number of ships approaching EoL, the share of remanufacturing should be
increasing due to its positive impact on the environment (Wahab et al., 2018).
Used-up EoL products or components received for restoration are of a significant
uncertainty and variability when it comes to their quantity and quality. In order
to determine key characteristics of remanufactured products, the following steps
should be undertaken (Lahrour and Brissaud, 2018):
1. Determining steps of the remanufacturing process
2. Proposing a framework of additive remanufacturing
3. Identifying key steps and characteristics of products that might be remanufactured by a chosen process
Remanufacturability evaluation should consider also effects of fatigue failure on the
model of the remanufacturing critical threshold. Such models were analyzed based on
a qualitative relationship between the fatigue life and remanufacturing requirements
and compared with existing remanufacturing evaluation systems as reference, proposing two new remanufacturability evaluation indexes (Wang, Yu et al., 2020).