1.1 Introduction
Cutting fluids are substances introduced into machining zones during metal cutting processes such as turning, milling, and drilling to reduce friction, dissipate heat, and improve tool life and surface finish (Kalpakjian & Schmid, 2014). They play a vital role in enhancing the overall efficiency of machining operations by lubricating the cutting interface, cooling the cutting area, and flushing away metal chips generated during the process. The choice of cutting fluid has a significant influence on machining performance, tool wear, workpiece quality, and environmental impact. Traditionally, mineral-based cutting fluids have been widely used in the manufacturing industry due to their effective lubricating and cooling properties. However, their use poses environmental and health hazards, as they are non-biodegradable, toxic, and contribute to soil and water contamination (Shashidhara & Jayaram, 2010).
This chapter will address the background information that motivated this study, the challenges that prompted it, its aim, and its objectives as a preface to subsequent sections of the study. Additional factors include the study's significance, scope, limitations, and the definition of technical terms.
1.2 Background of Study
Historically, cutting fluids and their applications in machining processes dates back to the early 19th century when water was initially used to reduce friction and cool the cutting zone during metalworking. According to Kalpakjian and Schmid (2014), the industrial revolution saw the introduction of mineral-based cutting oils as an improvement over plain water, due to their superior lubricating and anti-corrosive properties. As manufacturing technologies evolved, the need for more efficient, durable, and thermally stable cutting fluids increased, leading to the widespread adoption of petroleum-derived products across industries. However, as reported by Shashidhara and Jayaram (2010), the heavy reliance on mineral oils led to serious environmental and health issues due to their poor biodegradability and toxicity. Their disposal often resulted in soil and water pollution, while prolonged exposure to machine operators posed respiratory and dermatological risks.
Cutting fluids play a vital role in machining operations by reducing friction, minimizing heat generation, improving tool life, and enhancing the surface finish of machined components. According to Kalpakjian and Schmid (2014), the efficiency of any metal cutting process largely depends on the cooling and lubricating properties of the cutting fluid used. Traditionally, mineral-based oils have been employed as cutting fluids due to their effective cooling and lubrication performance. However, their non-biodegradability, toxicity, and adverse environmental effects have raised serious concerns in modern sustainable manufacturing systems.
Shashidhara and Jayaram (2010) reported that mineral oils contribute significantly to environmental pollution through improper disposal and contamination of soil and water bodies. In addition, prolonged exposure to these oils has been associated with various health hazards to machine operators, including skin irritation and respiratory problems. Ehinomen and Oyekanmi (2020) asserted that these environmental and health challenges have accelerated the search for biodegradable and renewable cutting fluids that will ensure safety, cost-effectiveness, and environmental sustainability in machining processes.
In response to these challenges, researchers have turned to vegetable oils as potential substitutes for mineral-based cutting fluids. According to Adesina, Oyetunji, and Bello (2018), vegetable oils are biodegradable, renewable, and possess excellent lubricating characteristics due to their high viscosity index and fatty acid composition. These properties make them suitable for use in high-friction environments such as drilling and turning operations. Ehinomen and Oyekanmi (2020) stated that the presence of long-chain fatty acids in vegetable oils forms a strong lubricating film that minimizes metal-to-metal contact, thereby reducing tool wear and improving machining efficiency.
Okafor, Ume, and Nwosu (2019) reported that tiger nut (Cyperus esculentus) oil has high oxidative stability and a rich composition of oleic acid, which makes it an effective lubricant in mechanical applications. Similarly, Oladipo and Hassan (2021) asserted that watermelon seed (Citrullus vulgaris) oil exhibits good thermal stability and film-forming ability, making it suitable as a bio-based alternative cutting fluid. Neem seed (Azadirachta indica) oil, as affirmed by Ehwarieme and Akintola (2019), possesses antibacterial and antioxidant properties that improve its resistance to oxidation and degradation during machining operations. These unique properties of the oils make them promising candidates for sustainable cutting fluid development.
Mild steel is a widely used engineering material in manufacturing industries due to its good machinability, weldability, and mechanical strength (Groover, 2017). However, during drilling operations, excessive heat generation and tool wear remain major concerns that affect the quality of machined surfaces. The efficiency of the cutting fluid used determines the level of thermal control, tool performance, and dimensional accuracy of the drilled holes. According to Adesina et al. (2018), the choice of cutting fluid directly influences cutting forces, temperature distribution, and the overall productivity of the drilling process.
In light of this, the assessment of vegetable oil extracts such as tiger nut, watermelon seed, and neem seed oils as cutting fluids in drilling operations of mild steel is a crucial step toward achieving environmentally friendly and sustainable machining. It provides valuable insights into the physical, chemical, and tribological performance of these natural oils under practical drilling conditions. Furthermore, it offers an opportunity to explore local agricultural resources as viable industrial lubricants, reducing dependence on costly imported mineral oils. This study is set against the backdrop of promoting eco-friendly and sustainable manufacturing practices through the use of renewable bio-based cutting fluids that enhance machining performance while preserving environmental health.
1.3 Statement of Problems
In metal cutting and drilling operations, the use of cutting fluids is essential for minimizing tool wear, reducing friction, lowering cutting temperature, and improving surface finish. However, most conventional cutting fluids are derived from mineral oils, which are non-biodegradable, toxic, and environmentally hazardous. The continuous use of such fluids poses serious health risks to machine operators, contributes to environmental pollution, and increases production costs due to disposal challenges and the rising cost of petroleum-based resources (Kalpakjian & Schmid, 2014).
Furthermore, the search for sustainable and eco-friendly alternatives to mineral-based cutting fluids is now a major concern in modern manufacturing industries. Vegetable oils have gained attention as potential substitutes because they possess high lubricity, good biodegradability, and low volatility (Ogunwande & Ojediran, 2020).
On the other hand, locally available vegetable oils such as tiger nut (Cyperus esculentus), watermelon seed (Citrullus vulgaris), and neem seed (Azadirachta indica) oils are abundant, renewable, and relatively cheap in many developing regions, including Nigeria. Their physicochemical properties, such as viscosity, flash point, and fatty acid composition, suggest potential suitability for metalworking applications. However, limited research exists on their comparative performance as cutting fluids, particularly in the drilling operation of mild steel (Ojo & Akinyemi, 2018). It is against this backdrop that this study seeks to assess the oil extracts from tiger nut, watermelon seed, and neem seed as cutting fluids in the drilling operation of mild steel.
1.4 Aim and Objectives of Study
The aim of this study is to evaluate the performance of oil extracts from tiger nut, watermelon seed, and neem seeds as cutting fluids in drilling operations of mild steel. In achieving this aim, the following specific objectives were laid out as follows:
- To evaluate the thermal and lubrication properties of the extracted oils during drilling of mild steel.
- To assess the effect of these oils on tool wear, surface finish, and chip formation.
- To compare the performance of the extracted oils with conventional mineral-based cutting fluids.
- To extract and characterize the oils from tiger nut, watermelon seed, and neem seeds.
- To determine the most effective oil extract for sustainable and efficient drilling operations.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- What are the physicochemical properties of tiger nut, watermelon seed, and neem seed oil extracts suitable for use as cutting fluids?
- How do the oil extracts affect tool wear, surface finish, and chip formation during drilling of mild steel?
- Which of the seed oils performs best in comparison with conventional mineral-based cutting fluids?
- What is the impact of using these oils on overall drilling efficiency and cost-effectiveness?
1.6 Significance of Study
It is believed that at the completion of the study, the research will inform manufacturers, researchers, and industrial practitioners about environmentally friendly and cost-effective alternatives to petroleum-based fluids. The study will also contribute to reducing occupational hazards and environmental pollution associated with conventional cutting fluids.
Furthermore, the study will provide data on the effectiveness of bio-based oils, helping manufacturers adopt greener and more efficient cutting fluids.
Lastly, the study will serve as a reference for academic research and curriculum development in manufacturing and materials engineering.
1.7 Scope of Study
The scope of the research is focused on the extraction and evaluation of oils from tiger nut, watermelon seed, and neem seed as cutting fluids for drilling operations specifically on mild steel. The research is limited to experimental investigations conducted within selected industrial workshops in Ogun State, Nigeria, using laboratory-prepared oil extracts and standard drilling setups.
1.8 Limitations of the Study
The study is limited to selected workshops and manufacturing companies in Ogun State, Nigeria, and the results may not be directly generalized to other regions or different types of steel. Limitations also include the variability in oil quality due to seasonal differences and extraction efficiency.
1.9 Definition of Terms
Cutting Fluid: A liquid or semi-liquid applied during machining to reduce friction, remove heat, and facilitate chip evacuation. According to Kalpakjian and Schmid, cutting fluids improve tool life and surface finish in metalworking operations.
Mild Steel: A type of carbon steel with low carbon content (0.05–0.25%), known for its ductility and ease of machining. Reported by Childs et al. as widely used in manufacturing due to cost-effectiveness and mechanical properties.
Tool Wear: The gradual degradation of cutting tools during machining operations due to friction, heat, and material interaction, which affects performance and surface finish.
Chip Formation: The process by which material is removed from the workpiece during machining in the form of small fragments. Stated by Ojo & Akinyemi as critical to evaluating machining efficiency.
Tiger Nut (Cyperus esculentus) Oil: Oil extracted from the tuber of the tiger nut plant, rich in monounsaturated fatty acids, used in food and industrial applications.
Watermelon Seed (Citrullus vulgaris) Oil: Oil derived from watermelon seeds, noted for favorable viscosity and thermal properties suitable for lubrication.
Neem Seed (Azadirachta indica) Oil: Oil obtained from neem seeds, known for its high lubricity and biodegradability, often used in industrial and medicinal applications.
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