Chip Formation Research Articles

Decoding physical sensor signals to reveal chip formation and surface deformation: An example in machining nickel-based superalloys

Decoding physical sensor signals to reveal chip formation and surface deformation: An example in machining nickel-based superalloys

Research on the chip formation mechanism of orthogonal cutting in particulate reinforced titanium matrix composites

Particle-reinforced titanium matrix composites (PTMCs) have recently become popular in the field of metal matrix composite research because of their outstanding mechanical properties. However, the diffuse distribution of strong reinforcing phases within a material influences chip formation, resulting in tool wear and lower cutting performance during machining. Examining the chip formation mechanism in PTMCs is crucial for enhancing machining performance. This paper explored how particles affect the chip formation process during the orthogonal cutting of PTMCs by utilizing both experimental and numerical methods for analysis. After characterizing the microstructure of PTMCs via image recognition technology, a finite element cutting model was established. Based on the dislocation theory, the effects of reinforcing phase damage and reinforcing phase content on the chip formation of PTMCs were analyzed. The results suggested that the chips exhibited a serrated shape with brittle cracks sprouting and expanding from the free surface. With a higher content of the reinforcing phase, the chip morphology of the PTMCs increases in terms of the degree of serration, and the chip formation process is influenced more by the particles. Furthermore, the chip formation results from a combination of thermoplastic shear instability, periodic fracture, and particle damage. As the cutting speed gradually increases, the PTMCs are more affected by the thermal softening effects, and the main cutting force generated during cutting gradually decreases from 625 to 589 N. Both the values and trends of the experimental results can verify the accuracy of the simulation.

Targeted Minimum Quantity Fluid Application in Machining

The surface integrity of a machined component is crucial for its service life part. One of the main final specifications that a machined part is inspected for is the surface integrity metrics, including surface residual stresses, surface microhardness, surface roughness, and microstructure. In this paper, the cutting fluid is strategically targeted to utilize heat energy effectively in the primary, secondary, and tertiary shear zones to positively affect the surface integrity metrics and machining mechanics. In this study, a lower quantity of the cutting fluids is targeted at the high-temperature zones to reduce the machining temperatures, thereby effectively simulating the effect of a ‘flood coolant’. The cutting fluid is applied simultaneously as a targeted Minimum Quantity Fluid (MQF) on the cutting tool’s flank and rake faces to improve the surface integrity metrics and chip formation. Also, this study analyzes the effect of the cutting fluid composition, the type of cutting fluid, and the amount of fluid quantities. The machining-induced surface integrity metrics are analyzed to understand the effects of targeted minimum quantity fluid application. The impact of the targeted application of cutting fluid on machining mechanics metrics, such as cutting forces and chip formation, is analyzed. Applying a targeted MQF application at the flank face of the cutting tool leads to higher compressive subsurface principal residual stresses. The results indicate that using MQF on both the flank and rake faces simultaneously enhances the surface integrity. The effect of a cutting fluid jet on the flank face is modeled to highlight the thermophysical properties that are crucial for selecting the appropriate cutting fluid to lower the machining-induced temperatures. With targeted MQF application, the fluid jet acts as a dynamic and external chip control mechanism. Overall, effectively managing temperatures in machining could enhance subsurface residual stresses and surface roughness using various cutting fluid combinations. Also, this paper presents a targeted cutting fluid application that improves the microstructural formation, enhancing chip control and producing machined surfaces and components with better surface integrity.

Feasibility study on fingerprinting organic and conventional mango fruits, chips, and juice using portable near-infrared spectroscopy.

This research examined the distinction between organic and conventional mango fruits, chips, and juice using portable near-infrared (NIR) spectroscopy. A comprehensive analysis was conducted on a sample of 100 mangoes (comprising 50 organic and 50 conventional) utilising a portable NIR spectrometer that spans a wavelength range from 900 to 1700 nm. The mangoes were assessed in their entirety and their juice and chip forms. The spectral data underwent pre-processing through methodologies such as multiplicative scatter correction (MSC), standard normal variate (SNV), and derivatives to enhance the precision of the models. Principal component analysis (PCA) and various multivariate classification algorithms, including linear discriminant analysis (LDA), random forest (RF), k-nearest neighbors (kNN), and partial least squares discriminant analysis (PLSDA), were utilised to categorise the samples effectively. The findings indicated that the random forest method and specific pre-processing techniques achieved the highest classification accuracy for distinguishing organic and conventional mango products. For mango fruit and chips, it achieved 88.76% and 77.98% accuracy, respectively, when pre-processed using the second derivative, while for juice, it achieved 87.53% accuracy without pre-processing. This investigation demonstrates the efficacy of portable NIR spectroscopy as a dependable and non-invasive method for verifying organic mango products, thereby enhancing the integrity of food labelling and fostering consumer confidence.

Investigation of Chip Morphology in Elliptical Vibration Micro-Turning of Silk Fibroin.

Silk fibroin, known for its biocompatibility and biodegradability, holds significant promise for biomedical applications, particularly in drug delivery systems. The precise fabrication of silk fibroin particles, specifically those ranging from tens of nanometres to hundreds of microns, is critical for these uses. This study introduces elliptical vibration micro-turning as a method for producing silk fibroin particles in the form of cutting chips to serve as carriers for drug delivery systems. A hybrid finite element and smoothed particle hydrodynamics (FE-SPH) model was used to investigate how vibration parameters, such as frequency and amplitude, influence chip formation and morphology. This research is essential for determining the size and shape of silk fibroin particles, which are crucial for their effectiveness in drug delivery systems. The results demonstrate the superior capability of elliptical vibration micro-turning for producing shorter, spiral-shaped chips in the size range of tens of microns, in contrast to the long, continuous chips with zig-zag folds and segmented edges generated by conventional micro-turning. The unique zig-zag shapes result from the interplay between the high flexibility and hierarchical structure of silk fibroin and the controlled cutting environment provided by the diamond tool. Additionally, higher vibration frequencies and lower vertical amplitudes promote chip curling, facilitate breakage, and improve chip control, while reducing cutting forces. Experimental trials further validate the accuracy of the hybrid model. This study represents a significant advancement in the processing of silk fibroin film, offering a complementary approach to fabricating short, spiral-shaped silk fibroin particles with a high surface-area-to-volume ratio compared to traditional spheroids, which holds great potential for enhancing drug-loading efficiency in high-precision drug delivery systems.

A comprehensive experimental investigation on the correlation between chip formation, machined surface integrity, and particle emissions during high-speed milling of TC4 titanium alloy

A comprehensive experimental investigation on the correlation between chip formation, machined surface integrity, and particle emissions during high-speed milling of TC4 titanium alloy

Research on contact friction characteristics of SiCp/Al tool-chip under quasi-intermittent vibration assisted swing cutting

In order to reduce the cutting force and tool wear during the processing of aluminum based silicon carbide composite materials, this study deeply explores the machining mechanism of quasi intermittent vibration assisted swing cutting of aluminum based silicon carbide composite materials. To this end, a tool-chip friction model was formulated to scrutinize the effects of cutting forces and chip formation under a spectrum of machining parameters. The findings indicate that the cutting force escalates with an increase in cutting depth and exhibits a trend of initial decrease followed by an increase with the rise in swing frequency. The tool swing characteristic of QVASC demonstrates superiority over orthogonal cutting (OC) in facilitating chip breakage. The experimental results show that when the cutting rate and vibration frequency are 10 m/min and 150 Hz, respectively, the length of the chips is the shortest. When the cutting depth and vibration frequency are 150 Hz, the cutting force is the smallest. The directional shifts in chip flow, instigated by the tool’s oscillation, induce horizontal bending of the chips, thereby easing their fragmentation and expediting chip removal, which in turn diminishes chip-tool interface friction. Moreover, as the cutting speed rises, the average length of chips tends to elongate. However, an increase in tool swing angle and frequency counteracts this trend, reducing the average chip length, with the frequency’s impact being notably pronounced. These insights provide direction for the application of SiCp/Al composite materials and the advancement of quasi intermittent vibration assisted swing cutting technology.

Understanding the influence of free-volume generation, thermal instabilities and fracture energy on shear localization in micromachining of bulk metallic glass

Bulk metallic glasses (BMGs) are a new class of amorphous metallic alloys having enhanced mechanical and tribological properties. However, the chip formation behavior of BMGs is not as well established as that of the crystalline materials, which hinders its prospective applications. In this paper, an orthogonal micromachining experiment is conducted, and chip morphology, force signature, hardness, and enthalpy of the machined surface are analyzed. The chips show segmented morphology with distinct fractures. The chip exhibits primary shear zones along with several secondary shear bands emanating within a single segmentation, which evidenced shear localization. Additionally, the machined surface exhibits softening as compared to the undeformed material. The shear localization, responsible for chip segmentation in BMG machining, is assumed to be driven primarily by free volume and the shear zone temperature. Hence, a localized chip segmentation model has been formulated by incorporating the effects of temperature and free volume generation-induced instabilities. The proposed chip formation model accounts for the contributions of the fracture and the new surface creation energies, in addition to the shear and friction energies used traditionally. The contribution of fracture energy was observed to be significant in the chip formation of BMGs. To differentiate between the relative contributions of temperature-induced instabilities and free volume generation on shear localization, four distinct regimes were identified based on the critical value of free volume flow coefficient (FVFC) and heat flow coefficients (HFC). The findings demonstrate that if the FVFC is greater than the critical value, significant shear localization takes place. Conversely, the shear localization becomes less pronounced if the FVFC is smaller than the critical values. Thus, it can be deduced that temperature has an insignificant role in shear localization, and free volume acts as the main driver.

Enhancement of health beneficial bioactivities of bitter melon (Momordica charantia L.) by puffing.

Effects of puffing and extraction method on physical and biological efficacy of bitter melon was investigated. Puffing increased the Maillard reaction products, extraction yield, total phenolic and total flavonoid contents. Antioxidant activity was the highest at 980kPa, but there was no significant difference between two extraction methods. However, methanol extraction showed higher anti-inflammatory, anti-obesity and anti-diabetic activities. Charantin was detected only in methanol extraction and increased with increasing puffing pressure. In addition to the remarkable increase in antioxidant activity, puffing could increase the charantin contents of BM. Methanol extract showed better biological efficacy excluding antioxidant activity than those of hot water extraction. Overall, puffing can be used as a method for increasing the functionality of BM, and it may be effective to consume puffed BM by itself such as the chip or powder forms without extraction for liberation and absorption of bioactive substances for the human body.

THREE-DIMENSIONAL FINITE ELEMENT MODELING OF METAL-BASED NANOCOMPOSITE DRILLING

In this study, a three-dimensional finite element model is developed in Abaqus software to investigate the drilling process of nanocomposites. The research focuses on modeling the chip formation process by incorporating nanoparticles separately and randomly within the metal matrix, providing a more realistic representation. Coulomb's law is utilized to model the friction between the tool and chip, while the Johnson-Cook model is employed to simulate plasticity and failure criteria. The modeling incorporates mechanical and thermal properties of materials as functions dependent on temperature. Dynamic analysis is conducted using Abaqus software to analyze the drilling process. The study reveals that raising the volume fraction of nanotubes from 1% to 5% results in a fivefold increase in required torque. Moreover, the axial force required for drilling increases significantly as the volume fraction of carbon nanotubes rises. For instance, drilling samples with volume fractions of 1%, 2%, and 5% require axial forces of 1,650 N, 1,670 N, and 4,560 N, respectively. These findings underscore the importance of considering nanoparticle volume fraction in optimizing the drilling process of metal-based nanocomposites.

Fundamental investigations on temperature development in ultra-precision turning

Ultra-precision machining represents a key technology for manufacturing optical components in medical, aerospace and automotive industry. Dedicated single crystal diamond tools enable the production of innovative optical surfaces and components with high dimensional accuracies and low surface roughness values in a wide range of airborne sensing and imaging applications concerning space telescopes, fast steering mirrors, laser communication and high-energy laser systems. Despite the high mechanical hardness of single crystal diamonds, temperature-induced wear of the diamond tools occurs during the process. In order to increase the economic efficiency of ultra-precision turning, the characterisation and interpretation of cutting temperatures are of utmost importance. According to the state-of-the-art, there are no precise methods for online temperature monitoring during the process at the cutting edge with regard to the requirements for resolution accuracy, response time and accessibility to the cutting edge. For this purpose, a dedicated cutting edge temperature measurement system based on ion-implanted boron-doped single crystal diamonds as a highly sensitive temperature sensor for ultra-precision turning was developed. To enable highly sensitive temperature measurements, ion implantation was used for partial and specific boron doping close to the cutting edge of single crystal diamond tools. Within the investigations, a resolution accuracy of 0.29 °C ≤ aR ≤ 0.39 °C could be proven for the developed cutting edge temperature measurement system. In addition, a total measurement uncertainty of uM = 0.098 °C was determined for the sensor accuracy aS in the investigated process area. For a rake angle range of 0° ≤ γ0 ≤ −30°, reaction times of 420 ms ≤ tR ≤ 440 ms were further determined. Using the developed cutting edge temperature measurement system enables a holistic view of the temperature development during ultra-precision machining, whereby a correlation between the measured cutting temperatures and the chip formation mechanisms depending on the applied process parameters could be identified. Within the investigations, the highest measured temperatures of ϑM = 50.18 °C and simulated maximum temperatures of ϑS,max = 183.12 °C were determined at a cutting speed of vc = 350 m/min, a cutting depth of ap = 35 µm as well as a feed of f = 35 µm using a rake angle of γ0 = −30°. The most uniform chips with the smoothest surfaces were identified within the chip analysis using a cutting speed of vc = 50 m/min, a cutting depth of ap = 5 µm and a feed of f = 35 µm with a measured temperature of ϑM = 21.30 °C and a simulated temperature of ϑS = 38.47 °C in the examined finishing area. According to the results, it was also shown that the cutting edge temperature measurement system with ion-implanted diamonds can be used for both electrically conductive and non-conductive materials. This provides the fundamentals for further research works to identify the complex temperature-induced wear behaviour of single crystal diamonds in ultra-precision turning and serves as the basis for self-optimising and self-learning ultra-precision machine tools.

A comparative study on drilling characteristics of unidirectional thermosetting CF/epoxy and thermoplastic CF/PEEK composites

Thermoplastic carbon fiber reinforced polyetheretherketone (CF/PEEK) composites are increasingly utilized as substitutes for thermosetting carbon fiber reinforced epoxy (CF/epoxy) composites in high-end equipment, due to their superior mechanical performance and sustainable manufacturability. For both composite components, drilling is an indispensable operation in the manufacturing process. To distinguish the drilling characteristics of the two composites, comparative experiments on drilling unidirectional CF/epoxy and CF/PEEK under different parameters were conducted in this paper. Several aspects, including chip formation, drilling temperature, thrust force, hole damage, and dimensional accuracy, were examined. Particularly, the impact of fiber cutting angle on exit and hole wall damage was considered. Results demonstrate that due to the higher ductility and toughness of PEEK, CF/PEEK produces continuous chips, higher drilling temperatures, higher thrust forces, and smaller damage areas than that of CF/epoxy. However, CF/PEEK has more serious hole wall subsurface damage and poorer dimensional accuracy since PEEK is sensitive to temperature. Consequently, unlike CF/epoxy, increasing spindle speeds at the low feed cannot improve the hole quality of CF/PEEK. Moreover, the hole damage distribution of both composites is strongly associated with the fiber cutting angle. This study provides guidance for high-performance machining of CF/PEEK.

Study on material removal of double abrasive grains in ultrasonic assisted abrasive cloth wheel of GH4169 alloy blade

As a critical component of aero-engines, the processing quality of the blade has a significant impact on the engine’s overall performance and service life. First, from the perspective of double abrasive grains, two finite element models—simultaneous and sequential scratches—are established. The interaction between the two abrasive grains affects not only the polishing force and chip formation but also the surface morphology of the processed workpiece. Second, the effects of abrasive grain rake angle, grain spacing, and ultrasonic amplitude on polishing force, chip formation, and surface morphology are analyzed using a single-factor method. Finally, conventional polishing and ultrasonic vibration-assisted polishing experiments using an abrasive cloth wheel are conducted. The results show that varying the transverse spacing between the abrasive grains reduces the polishing force on the second abrasive grain and leads to the formation of broken chips. Compared to conventional polishing, ultrasonic vibration-assisted polishing reduces the polishing forces by 9% and 8% in the tangential and normal directions, respectively, while also improving surface morphology and producing crushed chips.

Toward Sustainable Machining: Design and Fabrication of Micro-Textures on Solid Carbide Endmill Using Laser Micromachining

The modern machining industry is in a constant state of search for innovative approaches that can effectively improve productivity maintaining sustainability. Micro-texturing on the cutting tools is one of the innovative methods to improve the performance of the tool. The critical aspect of research related to micro-textured surfaces includes identifying the right texturing pattern, texturing intensity, and method. This article investigates the exploration of implementing projected sinusoidal curves as a novel micro-texturing pattern on the rake face of solid carbide endmill flutes, with a specific focus on the immense potential it holds in revolutionizing machining processes. A simulation using the textured tool was performed to study the chip formation, principal stress, and deflection during the machining process and is compared in the non-textured tool. The result of the study shows a better performance of the micro-textured endmill in comparison with the non-textured endmill. Micro-texturing is accomplished by employing advanced laser technology to create precise and controlled sinusoidal curves on the end mill surfaces at a micro-scale level. The average width and depth of the micro-texture on the endmill is found to be 93 µm and 101 µm respectively.

The Effect of Absorbed Hydrogen on the Rotors of Steel Machining Products During Powerful Turbo Aggregate Repairs.

Rotor shafts are the most heavily loaded and accident-prone parts of powerful turbine generators, which are cooled using hydrogen. To eliminate damage sustained during operations, repair work was carried out, including the removal of defective parts, surfacing, and turning. This study tested the machinability of the rotor shaft using prototypes made from 38KhN3MFA steel. A section of the shaft was degraded due to prolonged operation (250 thousand hours), and compared to the central part, a decrease in the average grain size from 21.57 μm to 12.72 μm and an increase in the amount of hydrogen absorbed during operation from 2.27 to 7.54 ppm were observed. With the frequency of dry turning increasing from 200 to 315 RPM, the chips changed their form from mostly rectangular with linear dimensions of 10 to 20 mm to large spiral rings with a diameter of 15 to 20 mm and a length of more than 50 mm. Cracks of 1 to 4 mm in length were found in most chip particles at both rotational speeds. Increasing the rotational speed from 200 to 315 and up to 500 RPM led to the formation of an oxide film on the surface of the specimens, as evidenced by the appearance of oxygen during local analyses of the elemental content on the chip surface. The saturation of specimens by hydrogen gas led to the formation of finer chips compared to the non-hydrated material, and the roughness of the machined surface increased at hydrogen contents of 6 and 8 ppm. In both dry and coolant cutting operations, surface roughness reflects the degradation of the rotor shaft or experimental prototypes due to hydrogenation, which can be used to diagnose the condition of the rotor after long-term operation.

The Simulation Analysis of Cutting Characteristics and Chip Formation Mechanism in Gear Skiving

The Simulation Analysis of Cutting Characteristics and Chip Formation Mechanism in Gear Skiving

PROCESS OF MAKING BANANA PEEL CHIPS (Musa paradisiaca Var Raja) USING DIFFERENT CONCENTRATIONS OF BETEL LIME SOLUTION

Chips are crispy snacks made from processed agricultural products and can be stored for a long time. The general criteria for chips are that they contain carbohydrates, have a dry appearance, make a sound when consumed, and are easily broken. The factors that encourage the formation of crispy chips include initial treatment in the form of soaking using materials such as lime solution. The purpose of this study was to determine the effect of soaking banana peels with different concentrations of lime solution on the quality of banana peel chips. This study used the Completely Randomized Design (CRD) method with 5 treatments, namely A = 0%, B = 2%, C = 4%, D = 6% and E = 8% as many as 4 replications so that 20 experimental units were obtained. The results of the study showed that the treatment of soaking in lime solution with different concentrations, namely A = 0%, B = 2%, C = 4%, D = 6% and E = 8% had a significant effect on the value of water content, ash content and organoleptic color, but did not have a significant effect on the organoleptic taste, aroma and texture. The banana peel chips product with the lowest water content was found in the treatment with a concentration of 8% lime (7.59%) and the lowest ash content in the concentration of 2% lime (10.94%). The best acceptance based on consumer preferences was obtained in the treatment without soaking in the solution betel lime (0%) with color characteristics of 3.67, taste 3.72, aroma 3.80, and texture 3.77 at the level of acceptance of liking.

Application of CVD Coated Turning Inserts in the Machining of ABNT 8620 Steel at Different Cutting Speeds

Objective: The objective of this study is to analyze turning inserts by evaluating their wear when increasing the cutting speed. Theoretical Framework: This topic presents the main concepts and theories that support the research. The use of CVD-coated turning inserts in the machining of ABNT 8620 steel stands out, reflecting scientific and technological advances that integrate several historical, cultural and social demands. Machining insert technology has been standing out for decades, and such research has led to an increase in the useful life of tools, in addition to ensuring a better surface finish and thermal control of the entire process. This ensures the industry savings in the use of inserts and results in reduced spending on purchasing new inputs and optimizes the material resources used. Method: The methodology adopted for this research involves using turning inserts to evaluate their wear when increasing the cutting speed. The material used as the test specimen in question is ABNT 8620, which remains the standard in all tests. For each test, the WNMG060408-TM insert was used to analyze aspects such as power, temperature and vibration. Results and Discussion: The results obtained revealed that by analyzing the machining chips, we can see that the formation of all of them was similar, and can be classified as spiral and not exceeding 40 mm, in the worst condition. This fact was to be expected and can be explained by the constant advance even with different cutting speeds, causing the material to remain within the chip formation zone. Research Implications: The practical and theoretical implications of this research are discussed, providing insights into how the results can be applied or influenced so that regardless of cutting speed, chip formation remains consistent under similar cutting conditions. Originality/Value: This study contributes to the literature due to the originality of the research, whether through an innovative approach, new discoveries or practical contributions. The relevance and value of this research are evidenced by the conclusion that the best cutting speed for this type of coating, insert and material is 350 m/min, having a better surface finish of the finished part, shorter chip length and a long contact time, providing the industry with a more aggressive cutting parameter and a good insert life, bringing with it greater productivity for the process.

A New Cutting Mechanics Model for Improved Shear Angle Prediction in Orthogonal Cutting Process

Abstract In metal cutting processes, accurately determining the shear angle is essential, as it governs chip formation and cutting force generation. Despite extensive research conducted on this topic, the accurate prediction of the shear angle remains a subject of ongoing investigation. This paper presents a new analytical model for predicting the shear angle, taking into account the direction difference between the shear stress at the boundary of the primary shear zone and the maximum shear stress. The constitutive property of the workpiece material with respect to the strain, strain rate, and temperature is considered in predicting the shear angle. The results show that the solution for the shear angle is not unique for a given rake and friction angle, and is highly dependent on the flow stress response of the workpiece material. Orthogonal cutting experiments were conducted on steel and aluminum alloys under various uncut chip thicknesses, cutting speeds, and tool rake angles to characterize the chip thickness and shear angle. Based on a comparison between model predictions, experimental results, and data from the literature for various workpiece materials and cutting conditions, it is shown that the proposed model results in an improved prediction for shear angle by considering the stress transformation within the primary shear zone.

Wear characteristics evolution of corundum wheel and its influence on performance in creep feed grinding of nickel-based superalloy

Wheel wear is an unavoidable occurrence in the process of creep feed grinding nickel-based superalloys, leading to reduced geometric accuracy, productivity, and surface integrity. Therefore, quantifying wheel wear forms and grinding performance is essential to minimize adverse impacts and optimize grinding processes. This study investigates the evolution of wheel wear and its consequences on grinding loads, chip formation, and surface quality. The results indicate that as the material removal volume (MRV) increases in the life cycle of the grinding wheel, the accumulation of timing damage leads to various forms of wear, mainly including grain fractures, material adhesion, attritious wear, and wheel clogging. The macro effects of the grinding ratio exhibit an initial increase followed by a subsequent decrease. At the micro level, the height of grain protrusions decrease, causing deviation from the normal distribution. Upon reaching the steady wear stage with an MRV of 9990 mm3, the wear flat rate and wheel clogging rate increase to approximately 10 % and 16.7 %, respectively. This indicates a significant rise in grinding thermo-mechanical load, serving as key indicators for evaluating the durability of grinding wheel. The presence of dull grains and material adhesion exacerbates the rubbing and ploughing effects, causing a transition of chip morphology from continuous flow to shear deformation, while heightened plastic pile-up contributes to elevated surface roughness. The intense thermo-mechanical coupling results in the formation of redeposited material and burn defects on the surface.