Machining of metals involves various processes that require the utmost accuracy and tool optimization which enhances efficiency. One of the major factors which impact the productivity and quality of machining is cutting oil also called metalworking fluid. This article aims to provide a detailed understanding of cutting oils such as their types, properties and application in metalworking processes. Readers will learn through the mechanics of these lubricants the impacts of choosing and administering cutting oils on tool life, equipment longevity, and the machining process overall. This guide seeks to assist not only industry experts, but also novices interested in metalworking by equipping them with foundational insights that enable them to navigate the metalworking industry more strategically.
What is the Role of Lubricant in Metal Machining?
During metal machining, lubricants are essential since they minimize friction between the tool and the workpiece, which decreases thermal energy, tool erosion, and wear. Moreover, lubricants aid in material dragging and surface finish enhancement. In addition, it aids in the evacuation of the chips, thus increasing the efficiency of machining while reducing the chances of causing damages to the equipment. The choice of lubricant depends on the material to be machined, machining speed, and nature of the operation to optimize performance, while controlling costs in industrial processes.
How Does a Lubricant Reduce Friction
Friction is reduced by a lubricant through the formation of a thin film around two opposing contact surfaces, thereby shielding them from friction and wear. This film can be a liquid, gel-like solid, or solid, and is determined by the operating conditions. Furthermore, lubricants increase motion by smoothing out rough surfaces and microscopic irregularities. On top of that, modern lubricants are enhanced with special additives that assist in the reduction of energy expenditure at higher demand levels, such as anti-wear agents and friction reducers. At the heart of it, lubricants improve the efficiency of industrial systems, and increase the lifespan of mechanical equipment while reducing their operational costs through the sustainment of optimal performance and minimal energy expenditure.
Update on Tool Life and Machining Efficiency
Cutting Speed:
Strikingly high cutting speeds result in tool wear and diminishing tool lifespan.
Least cutting speeds do not allow temperature to raise so that tool is spared for works.
Basic Values Range Are: 120 – 300 m/min (changes with material and tool makeup).
Feed Rate:
Improved feed rate is associated with reduced cycle times but may increase cutting forces and wear.
Basic Values Range Are: 0.1 to 2.0 mm/rev (may change with material).
Tool Material and Coating:
Tools made of carbide and ceramic along with coated tools prolong the tool life with an increased hardness.
Decrease in friction and increased resistance to wear is brought forth with titanium nitride or diamond like coatings.
Workpiece Material:
Less harder materials such as aluminum allows for higher speeds of the tool, while harder materials like steel sectors requires careful optimization on tool to avoid wear and overheating during machining.
Hardness Value Range (Usually): 50 to 200 HB (Brinell Hardness For Metalloids).
Cooling and Lubrication:
Used in excessive amounts, cutting fluids lead to reduction in friction along with heat and also help in removing waste material.
Common Fluid Types Are: Water soluble coolants, synthetic oil.
Depth of Cut:
Increase in material removal rates is associated with higher depths of cuts however this also causes increased tool stress and thermal loads.
Basic Values Range Are: 0.5 to 5 mm (depends on the purpose)
Importance of Lubrication in Various Machining Operations
Coolants can achieve a 15 to 50% temperature reduction. The extent of reduction is dependent on the workpiece material, cutting speed, and coolant type used.
Aluminum alloys: Daptation of temperature by an average of 40%.
Hardened steel: Daptation of temperature around 25%.
Appropriate lubrication can prolong the life of the tool from 30 to 70% by reducing the friction at the cutting zone.
Considerable increase in tool life for high-speed steel tools in mild steel machining is around 50%.
Tool’s life is improved by 35% for carbide tools in titanium machining.
Effective lubrication improves the surface finish through the reduction of material adhesion and chatter.
Notable values for Ra (Roughness Average):
In the absence of lubrication, also referred to as dry machining: 2.5 – 4.0 µm.
With lubrication (optimized): 0.4 – 1.5 µm.
Lubricants have a direct consequence on chip morphology and evacuation.
Water-soluble coolants possess a 20 to 30% improvement for chip breaking efficiency relative to their synthetic counterparts.
Performance facts such as these aid engineers in adapting their lubrication strategies to set machining specific targets such as precision, durability, cost, and eco-friendliness.
What are the Different Types of Cutting Fluid?
Understanding the Applications of Soluble Oil
Soluble oils belong to a class of cutting fluids that consists of mineral oil emulsions, having around 30-85\% of their volume made up of water, emulsifiers, biocides, and anti-corrosion additives. They are very effective during cooling and lubrication in various machining such as drilling, turning, and milling operations. The considerable amount of water gives a high level of cooling, preventing tool thermal deformation, while the oil provides enough lubrication to avoid high friction levels. Their versatility and cost-effectiveness provide them great value for use in operations with a balance between cooling and lubricant characteristics. Their performance is, however, challenging to manage due to bacterial growth and emulsion stability over time.
From Traditional Oils To Synthetic Fluids
The comparison of neat oils and synthetic fluids leads to the following conclusion – each of them showcase both differing benefits and performance drawbacks when looking at defining standards of performance-based metrics.
Neat oils, being composed of soy and canola oil, stand out for their high viscosity and oil based composition, offering them upper hand in lubrication. This makes them particulary useful in heavy duty machining operations such as broaching or deep hole drilling. Viscosity maintained under high pressures translates into dependable force and longevity of tools.
Viscosity range: 15-220 cSt at 40°C
Typical Limiting Values:
Max Value (specific/operational)Min Value (ML/l)Viscosity (cSt)
Load Specific and Application Viscosity is Defined Above 50 mPa.s Sengage
Tool Life Improvement: Up to 30% vs. synthetic fluids at high load applications
Neat oils have lower microbial decay, thus allowing for reduced maintenance. On the contrary, they yield more waste and are less eco friendly.
Water-soluble synthetic oils provide higher emulsion stability, thus are better for the environment while needing close monitoring to maintain sink emulsion stability.
Thermal Conductivity: ~0.58 W/mK
Recommended Usage: Cutting speeds over 500 m/min
Reduction of heat deformation plays a vital role in the water cooling these oils can provide to the tool and work piece during machining ensuring suitable processes at high speeds.
Effective thermal conductivity offers support for processes such as the aforementioned while making them suitable for milling and high speed machining during the high critical cooling phase.
Maintenance Cycles: Monthly oxidation for neat oils, weekly pH and concentration checks on synthetic fluids.
The aforementioned highlights the factual importance of checking the essence of the fluid the tooling is required to balance lubrication, cooling, and maintenance demands.
What Cutting Oil to Utilize with Distinct Materials
To achieve optimal performance, mechanical quality, and tool life, distinct materials require certain types of cutting oils. Below is a summary listing the recommendations of cutting oil for various materials:
Recommended Oil Type: Soluble Oils or Semi-Synthetic Fluids
Characteristics: Staining and corrosion of the material is minimized, while excellent lubrication is maintained.
Recommended Oil Type: Neat Oils or Synthetic Fluids with Extreme Pressure (EP) Additives
Characteristics: Enhance protection against wear during high-temperature machining operations and overall thermal stability.
Recommended Oil Type: Chlorine-Free Neat Oils or Heavy-Duty Synthetic Fluids
Characteristics: Reduction of galling and improvement of finish quality is greatly improved due to enhanced lubrication.
Titanium and High-Temperature Alloys
Recommended Oil Type: High-Viscosity Neat Oils or Special EP Additives Synthetic Fluids
Characteristics: Effective heat dissipation and tool performance enhancement is provided under extreme machining conditions.
Recommended Oil Type: Synthetic Fluids or Soluble Oils with Low Viscosity
Characteristics: Tool and chip fouling is prevented via lowering built-up edge (BUE) and debris.
Recommended Oil Type: Soluble Oils or Chlorine-Free Synthetic Fluids
Characteristics: Prevention of surface integrity changes and discoloration leading to better low-speed machining supporting.
Recommended Oil Type: Lightweight Soluble Oils or Water-Based Cooling Fluids
Characteristics: Even cuts along with reducing thermal distortion and no chemical interaction with the material is ensured.
This chart illustrates how to choose cutting oil for safety, performance, and environmental protection based on the material being cut. Performance and sustainability are key with this approach.
How to Choose the Right Metalworking Fluid for Your Machine?
Considerations to Make When Selecting the Appropriate Fluid
These fundamental guiding principles will help you select a fluid that will work with both the metalworking process and the material being machined.
- Material Type: Different materials require specific fluid properties. For instance, ferrous alloys need rust inhibitors in the fluid while non-ferrous alloys are better off with low activity varnish non-staining formulations.
- Environmental Compliance: Using non biodegradable fluids highly contradicts the OSHA’s goals which are to protect the worker’s health as well as cut down on the contamination of nature.
- Machine Usage: Check the fluid for possible corrosion, residue formation, or any other damage that might be inflicted to the machine by the fluid.
Achieving a balance among all these helps optimize operational efficiency and precision while prolonging the equipment durability and life.
Role of Metal Being Worked
The particular type of metal to be worked with will greatly affect the kind of cutting fluid to be used. Each material has specific thermomechanical behaviors which affect how machining will be performed on it. Following are considerations for some common metals:
Aluminum: Since this metal is quite soft, it tends to stick to cutting tools and thus, requires a cutting fluid with strong lubrication. Recommended fluids are water-soluble with anti-welding additives. Certain aluminum alloys that contain high amounts of silica may need extra cooling to efficiently get rid of chips.
Stainless Steel: The strength and thermal conductivity of this type of steel is relatively high which results in having too much tool wear—or too much heat being created—at one time. To avoid galling and to promote longer tool life, high-performance cutting fluids that incorporate cooling, extreme pressure (EP) additives, and others are required. Studies indicate that up to 30% of tool wear rates in machining processes of stainless steel are reduced by the use of EP fluids.
Cast Iron: Cast Iron is brittle in nature and this results in precision milling generating fine particles and dust. While dry machining is the most common method used, if cutting fluids are to be used, lower viscosity oils or water-based alternatives are the most effective in getting rid of dust without creating sludge.
Titanium Alloys: As a result of possessing a high strength-to-weight ratio alongside heat resistance, titanium alloys require cutting fluids with extreme cooling ability to control thermal buildup. Research suggests that the machining efficacy of titanium alloys is enhanced with the use of high-pressure coolant delivery systems by as much as 20%.
Knowing these properties enables more precise matching of cutting fluids to the materials being machined, optimizing performance, which translates to improved productivity and lower costs.
Impact on Productivity, Quality of Work, and Wording
To analyze more specifically the impact of cutting fluids on machining titanium alloys, the following metrics were recorded:
Tool life with high-pressure coolant systems increases by approximately 25-35% in comparison to standard cooling methods.
Enhanced lubrication minimizes friction and wear on the tool, as well as undercutting in high-speed machining.
Usage of cutting fluids results in an average surface roughness reduction of up to 40%.
The most reliable surface profile is provided The removal of chips and debris.
Cutting fluid applications lower cutting temperatures by an estimated 50-70°C, thermally shocking the tool and workpiece.
This effect is most critical for maintaining the integrity of the structure in titanium alloys.
By adjusting your cut speeds and feed rates, high-performance cooling systems can help you reduce cycle times by up to 20%.
You do get significant savings in production time and precision is not made lower at all.
The prevention of tool re-cutting and reduction of work surface defects is achieved by improvement of fluid delivery for chip evacuation, which is enhanced by 30%.
What are the Best Practices for Managing Coolant in CNC Machines?
Maintenance of the Coolant System in CNC Machines
Correct maintenance of the coolant systems of CNC machines is very important for proper operation, tool longevity, and preservation of precision in machining. The following guidelines should be observed:
Check the coolant level, concentration, and pH balance at the least on a quarterly basis. All parameters must meet specified benchmarks. Corrosion, bacteria, and lessened cooling ability can be caused due to improper coolant concentration.
High-performance filtration systems must be applied for the extraction of chip, debris, and finely graded particles from the coolant. This ensures that the coolant does not lose its integrity or hurt the machine and tools.
Coolant tanks must be cleaned periodically to remove sludge and other microbial growth. System sanitation creates a cleaner environment while prolonging coolant life.
Use CNC form of coolants because they offer superior lubrication, heat, and resistance to bacterial formation which is good for the machine.
Consistency, ajustment of coolant flow rate and temperature, to the required parameters that match the machine operation should be done to prevent overheating and ensure efficient chip removal during high-speed operations.
Following these procedures will allow for better trust in the machines, less down-time, and overall improvement in the quality of changes made to the systems.
Addressing Tramp Oil and Contamination Issues
Tramp oil and contamination in working metal fluids can negatively affect machining operations and their end product. The sources of oil contamination may include bleed and feed hydraulic systems, ambient dust and chips, or even the breakdown of cutting fluids due to their own use. The tramp oil contaminant causes high bacterial proliferation, emulsion inefficacy, and lubrication stagflation which can lead to an ineffective machining process and reduced tool longevity.
Studies show the presence of tramp oil can account for up to 15 – 25 percent increase on lubricating effectiveness decrease for every 1-2 percent surge on tramp oil concentration in the coolant system. This leads to greater lubricant viscosity, elevating tool wear and tear, and generating excess friction. Particulate matter above the 10-micron threshold is especially fatal as these contaminants tend to result in faster damage to tools as well as surface treatment on parts that are machined.
Best practices for tramp oil control involve the periodic application of oil skimmers or centrifuge systems to recover oil from the coolant reservoir. Implementation of a strong filtration unit that can trap particles smaller than 5 micrometers will also reduce contamination. Use of refractometers and pH testing allow for the monitoring of the cutting fluid composition ensuring that the coolant retains its intended attributes. Proper maintenance strategies and early detection techniques combined can reduce contamination-related problems by 40% according to engineering studies.
Maintaining Adequate Levels of Coolant and Lubricants
For machinery, maintaining strict oversight of both coolant and lubricant quality is a prerequisite to their proper functioning. Given below is a record of underlying data points and other relevant factors:
Particulate Size Captured: Smaller than five microns
Recommended Filtration Methods:
High Pressure Filters
Magnetic Filtration Systems
Vertical Ayers s suction filters and centrifugal cleaning
Optimal Concentration Levels
Correct range of coolant concentration: 5% to 10% (depending on the specific use)
Methods of Monitoring:
Regular pH monitoring to ensure consistent range (ideal range is between 8.5 to 9.2)
Periodic pH measuring with hand-held refractometers for more reliable concentration assessments
Potential Contaminants:
Tramp Oil
Fine Metal Particulate
Fungal or bacterial contamination
Management Practices:
Regular tank and reservoir cleaning and maintenance as routine cleaning
Biocide treatment as soon as there is suspicion of microbial contamination
Tramp oil removal through skimming devices
Routine Monitoring Frequency
Concentration Testing: Every one to two days for machines under high usage
Full coolant replacement cycle:
Every six months for low intensity applications
Every three months for high intensity applications
System optimization
Temperature control:
Ideal operating: 60°F to 90°F (15 °C to 32 °C)
Temperature extremes are controlled with heat exchangers or cooling units
Flow Rate Recommendations:
Smoothing lubrication carried out with flow rates within the boundaries set to 2 – 5 gallons per minute (GPM)
Sticking to these parameters allows organization’s sharpen operational efficiency, increase unplanned downtime, and slow down for overused cutting fluids and machine parts.
How Do Different Metals Influence the Choice of Cutting Fluid?
Additional Details for Other Stainless Steel Alloys
Selection of cutting fluids with high lubricity is a requirement for reducing heat and work hardening during stainless steel machining. Aluminum or titanium alloys require cutting fluids that are more cooling to reduce thermal expansion and retain surface finish quality. The cutting fluid must be compatible with the metal fluid to prevent detrimental chemical reactions that could damage the material or performance of the tool.
Working with Ferrous Metals and Their Challenges
For ferrous metals, critical issues include heat control, tool life, and surface oxidation. Containing iron, these metals are harder and tougher, which necessitates strong cutting tools made of carbide or coated high-speed steel. Risks of thermal deformation also require effective cooling cutting fluids. Enhanced efficiency in machining is achieved through proper chip evacuation and consistent cutting parameters to avoid excess tool or material damage. Reliable and high-quality results require proactive maintenance of the tools and equipment used.
Changing Tool Life Strategies per Metal
When optimizing tool life during cutting of different metals, the following data values and parameters need attention:
Plain low carbon steel: 100 – 150 ft/min
Stainless steel (Austenitic): 50 – 80 ft/min
Soft aluminum alloys: 300 – 600 ft/min
Steel (Medium-Cutting): 0.010 – 0.020 in/rev
Gray iron (cast iron): 0.005 – 0.015 in/rev
Aluminum (during high-speed machining): 0.005 – 0.030 in/rev
Hard metals (tool steel): 0.030 – 0.050 inches per pass
Malleable metals (aluminum): 0.050 – 0.100 inches per pass
Moderate speed and low-cost applications use High-Speed Steel (HSS).
Carbide Tools: Used in high-speed operations and are thermally wear-resistant.
Ceramics and Cermets: Recommended for extremely high cutting speeds and dry machining.
Water-Soluble Coolants for primary machining.
Synthetic Coolants for precision work and thermal stability.
Cutting Oils for low speed lapping and lubrication required operations.
Positive Rake Angles for softer materials like aluminum and brass.
Neutral Rake when cutting steels to maintain edge strength.
Negative Rake Angles for harder alloys to increase tool life through minimized wear.
Contaminant free Dry Machining for non-ferrous materials.
Flooding with coolant is ideal for tools made of high speed steel and carbide during heavy cutting.
Localized Mist Application is used for cooling and avoiding evaporation.
What are the Latest Innovations in Machining Lubricants?
Innovations in Technology Surrounding Metalworking Fluids
The recent developments in machining lubricants target operational efficacy, environment friendliness, and worker safety. Some of the changes highlighted below will be discussed alongside supporting details and data.
Additional Additive Synthetic Lubricants: More advanced synthetic fluids include new additive technologies designed for enhanced lubrication and heat transfer sponsion problem. A report from industry in 2022 noted that synthetic lubricants could out-perform mineral oil-based lubricants in tool wear by as much as thirty percent, increasing the tool life and reducing the operational costs.
Biodegradable and Environment Friendly Fluids: Stricter regulations on environmental protection and other policies have driven research into lubricants based on renewable resources like vegetable oil. Studies conducting cutting and grinding of these fluids show at least a twenty percent reduction in thermal damage during machining, marking them as a suitable sustainable option.
Nanotechnology Application: Research related to nanoparticle infused fluids demonstrates major improvements in friction heat reduction and heat transfer efficiency. In 2021, a study noted a forty percent reduction in cutting forces during the machining of titanium alloy with the application of nano lubricant.
Low-foaming and High Tailorability Designs: Modern lubricants are increasingly designed to be low-foam for high-pressure systems while allowing foam-tailorability to meet specific industry requirements. For example, lubricants tailored for aerospace applications enhanced machining complex alloy dimensional accuracy by 25%.
These developments illustrate how the industry is striving to achieve a balance between performance, sustainability, and cost-efficiency for the growing demands of contemporary manufacturing processes.
Innovative Solutions from Master Fluid Solutions
The following data highlights the measurable market and operational gains offered by advanced lubricant innovations across the industries:
Enhanced biocompatibility of lubricants to meet more stringent regulations.
Increased dimensional accuracy in machining alloys by 25%.
Improved surface finish quality, achieving roughness values below 0.4 µm.
Improvement in tool wear reduced by 30% extending tool life.
Decrease in energy consumption during machining by 20%.
Fluid waste generation decreased by 35% improving environmental sustainability.
Enhanced precision micro machining processes with tighter tolerances achieved by 40% improvement.
Process downtime due to improved biostable fluids was reduced resulting in 50% lower maintenance requirement.
Machining throughput for large components improved by 18%.
Operational temperatures lowered by an average of 12% reducing deformation from heat.
Maintenance free biostable fluids providing increased system reliability made significant improvements in system uptime.
The development of eco-friendly lubricants with biodegradable components helps reduce the overall environmental impact.
The Development of Coolant and Lubricant in Metal Machining
The application of modern coolant techniques has provided measurable operating improvements in metal machining. Based on thorough evaluation and application, the key data points are as follows:
Increased coolant lifespan: Enhanced filtration systems increased coolant life by an average of 35%, lowering coolant replacement and associated system <downtime>.
Reduction in Energy Expenditure: Facilities with energy-efficient coolant pumps evidenced a 22% drop in energy utilization leading to additional cost and sustainability targets.
Surface Finishing Quality: Stricter compliance with precision components technical specifications due to advanced surface roughness (Ra) metrics surpassing 15% improvement on audeed surface.
Improved Employee Safety: Volatile particulate matter in the air was reduced by 30% due to low-volatile new coolants, enhancing workplace cleanliness and safety.
Frequently Asked Questions (FAQs)
Q: What significance do metalworking fluids hold for metal machining?
A: Metalworking fluids are essential for metal machining since they facilitate lubrication, cooling, and chip removal. Their use reduces frictional contact at the cutting edge, improves tool life, and enhances the quality of the product. Choosing the correct metalworking fluid is important for maximizing performance while safeguarding the tools and equipment used.
Q: What parameters should I consider before cutting oil is applied to a type of metal?
A: A specific type of cutting oil is determined by the type of metal to be machined, the machining operation employed, and the level of polish required. Different cutting oils may be needed for materials such as aluminum, steels, and even titanium. Master fluid solutions assist machinists with selecting the appropriate oil for a given task.
Q: Are there differences between oils used for different types of machining operations?
A: Yes, there are oils differ from one machining operation to the other. For instance, very high speed operations are likely to need a cutting oil of high content in oil for effective lubrication and cooling as opposed to lower speed operations where a different formulation is needed to prevent excessive residue buildup.
Q: Can motor oil be used in a machining process?
A: No. Motor oil is not suggested for use in machining operations because it does not have the characteristics that make metals working efficient. In metalworking fluids, their formulations are usually tailored to provide adequate cooling, lubrication, and even chip removal that motor oil cannot provide.
Q: How do machinists handle chips from the cutting process?
A: Chip removal from the cutting process is done by the application of the proper metalworking fluids and tools. These fluids assist in removing pieces of metal from the working region which would otherwise remain in the way and ensure that an unobstructed cut with smooth finish is achieved.
Q: What considerations apply for applying titanium cutting oils to titanium and other similar metals?
A: When dealing with titanium metals specifically, their cutting oils need special attention on temperature tolerances and limitations regarding lubricational effectiveness of the oils. Soils also needs to attend to specialized configurations to aid in the machining of titaniums.
Q: What other functions does having a high concentration of oils in some cutting fluids serve?
A: High concentrations of oils or fats in some cutting fluids primary functions rest in the lubrication as well as the cooling of the machine’s parts during either heavy workload or rapid succession drives. In other ways, there is less friction, ensuring lower heat creation and further ensuring longevity of the cutting tools employed.
Q: In what respects do steels possess similar machining works?
A: The similarity in the alloys’ physical characteristics explains why steels often renew a number of machining operations. That winning at the supper put it tells us the patent composition and nature of the machining done onto a metal affects the type the compress machine oil used. Master fluids help aids any professional o ill adapting to optomis aid the formulated called fuids of this type heavily tailored to the steeled being worked on.
Q: Do I need to consult specialists when picking metalworking fluids?
A: For example, consulting master fluids solution professionals may prove to be very helpful with metalworking fluids selection. They provide information into what is required for a given application ensuring that the correct cutting fluid selection which boosts the performance and efficiency is made.
Reference Sources
- Conventional and Recent Advances of Vegetable Oils as Metalworking Fluids (MWFs): A Review
- Authors: Inês S. Afonso et al.
- Publication Date: March 30, 2023
- Summary: This review discusses the historical and contemporary use of vegetable oils as metalworking fluids. It highlights their biodegradability and environmental benefits compared to traditional mineral oils. The paper emphasizes the importance of additives to enhance the performance of vegetable oils, such as improving lubricity and cooling properties. The review concludes that vegetable oils are a viable alternative to conventional MWFs, especially in environmentally sensitive applications(Afonso et al., 2023).
- Tribological Effects of Metalworking Fluids in Cutting Processes
- Authors: F. Pape et al.
- Publication Date: May 16, 2023
- Summary: This study investigates the tribological performance of various metalworking fluids during cutting processes. It examines the effects of lubricant film formation and cooling conditions on tool wear and chip transport. The findings indicate that the boundary friction of MWFs significantly influences the machining process, suggesting that the selection of appropriate additives can enhance performance(Pape et al., 2023).
- Characterization and Machine Learning-Based Parameter Estimation in MQL Machining of a Superalloy for Developed Green Nano-Metalworking Fluids
- Authors: Muralidhar Vardhanapu et al.
- Publication Date: February 14, 2023
- Summary: This paper characterizes the performance of newly developed green nano-metalworking fluids in Minimum Quantity Lubrication (MQL) machining of superalloys. The study employs machine learning techniques to estimate optimal machining parameters, demonstrating that the use of nano-fluids can improve machining efficiency and reduce environmental impact(Vardhanapu et al., 2023, pp. 1–34).
