Natural fiber–reinforced composites: A review on material, manufacturing, and machinability

Abstract

Interest in natural fiber–reinforced composites (NFRCs) is increasing rapidly thanks to their numerous advantages such as low cost, biodegradability, eco-friendly nature, relatively good mechanical properties, and a growing emphasis on the environmental and sustainability aspects of engineering materials. However, large-scale use of NFRCs is still considered as challenging due to the difficulties in manufacturing, limited knowledge of its machinability and appropriate parameter settings, and being prone to machining-induced defects. This article presents a comprehensive review on various aspects of NFRCs, with a focus on the manufacturing and machinability. It covers some recent works related to NFRCs, including the manufacturing processes and parameters, characterization of mechanical properties, applications, and machinability and machining process monitoring, many for the first time. The main challenges associated with machining of NFRCs and the induced damages are outlined, with special attention paid to the effect of physical properties of the fibers and manufacturing process on the machinability, along with the essential machining parameters that affect the quality of the machined surface. The research perspectives and the current application status are also discussed. The article is intended to help readers attain a fundamental understanding of key technologies and the state of the arts in this research area.

Cutting Processes of Natural Fiber-Reinforced Polymer Composites

“…NFRPs are classified based on another classification of polymer based into two types, natural fiber-reinforced thermoplastic polymer that can be remolded and recycled, the other type is natural fiber-reinforced thermosetting polymers which cannot be remolded [ 20 ]. Reinforcement natural fibers are taken from natural sources, either animal, plant, or mineral [ 11 , 21 , 22 ]. In accordance to the source, natural and synthetic fibers can be classified as shown in Figure 1 .…”

“…For example, the turning process is not cost-effective because of high tool wear, in addition to poor surface finish [ 1 ]. Another example of an inefficient process is ultrasonic machining because it is a very slow process caused by the relatively low material removal rate, and it is relatively expensive and unsuitable for quantitative production [ 11 , 12 ]. Since composite materials are manufactured close to the final shape [ 9 , 11 ], the commonly used cutting processes for making holes, trimming or making profiles are covered in this study.…”

“…Cutting speed, feed rate, and tool geometry are the controlling parameters in this type of cutting processes whether it is for cutting composite materials or metals [ 1 ]. Unconventional methods, on the other hand, include relatively modern processes such as laser beam cutting technology and abrasive water jet cutting process, [ 11 , 18 ] and these methods are the focus of this paper. Both processes have a number of control parameters that are discussed separately in this survey.…”

“…[ 2 , 4 , 6 , 7 , 8 ]. Although the NFRP composites are manufactured near-net shape, they still need some final cutting processes to reach the shape required such as drilling, cutting, and trimming processes [ 9 , 10 , 11 , 12 , 13 , 14 ]. Composite materials do not behave like conventional materials under different cutting processes, because of their different properties.…”

“…Which operating parameters are optimal when using a specific cutting process? Cutting processes can be classified into conventional processes that use solid tools such as drilling, sawing and milling, and non-traditional processes which include laser beam machining (LBM), ultrasonic drilling [ 11 ], and abrasive water jet machining (AWJM) [ 19 ]. The most common methods of cutting NFRPs are covered in this study to answer the questions above on determining which cutting methods are more suitable for cutting NFRP composites and which operating parameters are optimal for each process.…”