Traditional Grinding Method Research Articles

A Review of High-Speed Turning of AISI 4340 Steel with Minimum Quantity Lubrication (MQL)

AISI 4340 is a medium-carbon low-alloy steel that has gained distinctive attention due to its advanced properties including high strength, high toughness, and heat resistance. This has led to its commercial usage in a wide variety of industries such as construction, automotive, and aerospace. AISI 4340 is usually machined in a hardened state through a hard-turning process, which results in high heat generation, accelerated tool wear, low productivity, and poor surface quality. The application of high-speed machining helps improve the material removal rate and surface finish quality, yet the elevated temperature at the cutting zone still poses problems to the tool’s lifespan. Apart from using advanced cutting tool materials, which is costly, researchers have also explored various cooling methods to tackle the heat problem. This paper presents a review of a sustainable cooling method known as minimum quantity lubrication (MQL) for its application in the high-speed turning of AISI 4340 steel. This study is centered on high-speed turning and the application of MQL systems in machining AISI 4340 steel. It has been observed that the hard part turning of materials with a hardness exceeding 45 HRC offers advantages such as improved accuracy and tighter tolerances compared to traditional grinding methods. However, this process leads to increased temperatures, and MQL proves to be a viable alternative to dry conditions. Challenges in optimizing MQL performance include fluid penetration and lubrication effectiveness.

Fabrication of polycrystalline diamond micro-milling cutter with different grain sizes by picosecond laser

Polycrystalline diamond (PCD) is an excellent material for machining micro-tools due to its high hardness and wear resistance. However, the diameter of micro-milling tools is generally required to be less than 500 μm. When preparing micro-milling tools with a large aspect ratio, the processing load introduced by traditional grinding methods is easy to cause tool fracture. Therefore, a composite structure of carbide tool holder and diamond tool head is proposed in this paper. A technique of picosecond laser machining PCD micro-milling tool was studied, and the overall manufacturing process of tool blank preparation, nanosecond laser roughing and picosecond laser finishing was formed. A two-dimensional ablation mathematical model for tangential machining of PCD with a multi-pulse picosecond laser was established, and experiments verified the reliability of the mathematical model. In addition, the effects of picosecond laser pulse pitch, pulse energy, and track spacing on the surface quality of PCD materials with different particle sizes and cutting edge radius were studied by orthogonal experiments. The results showed that after picosecond laser processing, the surface roughness (Sa) of PCD with a particle size of 2 μm was the best, which can reach 0.33 μm, and the cutting edge radius of PCD micro-milling tool with a particle size of 25 μm was the smallest, which can get 1.67 μm. Using the optimized picosecond laser parameters, the high-sharpness single-edge micro-milling cutters with different particle sizes PCD with a diameter of 100 μm, aspect ratio greater than 3, and a cutting edge radius less than 3 μm were successfully fabricated.

Straightening of the rollers of planetary roller screw — Design of straightening die and experimental validation

The roller of a Planetary Roller Screw (PRS) is prone to bending deformation and runout error after carburizing, which results in the uneven transmission performance, increased transmission friction, and decreased service life. Traditional grinding methods used to rectify these errors have high costs and low efficiency and furthermore reduce the thickness of the carbon layer of the roller. This paper proposed a new radial feed-in straightening method to correct the geometric errors of carburized PRS rollers. Trial tests are first performed to explore the feasibility of different straightening techniques, as well as to discover key factors for the rational design of a straightening die. Based on the trial tests, a new tooth profile model of the straightening die for the PRS roller is proposed. Finite element models are developed to analyze the material flow feature of the straightening process, as well as to verify the effectiveness of the proposed tooth profile model of the straightening die. For mass production needs, experimental tests are performed to further examine the performance of the proposed straightening method. It is found that reducing the tooth contact interference between the roller and die can effectively increase the quality of the straightened workpiece. Results show that the bending deformation and runout error of the carburized PRS roller are effectively corrected by the proposed straightening process. Furthermore, the smoothness of the tooth surface of the roller is significantly increased, and all the tested samples meet production quality standards after straightening. A comparison of transmission performance under 0.3 million cycles shows that the maximum friction torque (1.82 N·mm) of the PRS product with straightened rollers is much better than without straightening (105.70 N·mm).

Improvement of the hydraulic system in a rail grinder based on the grinding effect

Rail grinding is an important method for metro rail maintenance. The rail grinding process is a mechanical, electric, and hydraulic coupling process built on vehicle-track relationship. A low grinding power may result in a low grinding effect, whereas a high grinding power may cause a white layer and damage to the rail. Constant-power grinding is the traditional grinding method, and the grinding effect is constrained by this undifferentiated grinding style. In this study, first, a rail grinding model is established. The goal of this study was to improve the hydraulic system by installing check valves at the oil inlet and outlet. The grinding pressure at the peak of rail irregularity was increased through the delayed pressure relief induced by these valves, and the grinding effect was improved. Normal corrugation allows for the maintenance of the grinding pressure and an improvement in the peak clipping effect. Under severe corrugation, the grinding pressure can be released and the grinding power fluctuation can be narrowed. The difference in corrugation depth before and after grinding under normal corrugation was taken as the objective function. The extreme value of grinding power under severe corrugation is a boundary condition. The cracking pressure of the check valve in the oil outlet was optimised. The optimal cracking pressure of this check valve was analysed in this study using modelling and simulation. The results showed that the optimal cracking pressure for this valve was 60 psi. The grinding effect increased by 12.7% under normal corrugation using this improved technique. Additionally, during severe corrugation, maximum grinding power is 30 kW, which is within the allowable range.

Laser-assisted grinding of silicon nitride ceramics: Micro-groove preparation and removal mechanism

Efficient grinding of Silicon Nitride ceramics has always been impeded by the inevitable fracture cracks and lower removal rate. This paper is devoted to investigate the efficient grinding mechanism of ceramics by Laser Assisted Grinding(LAG) method, which focuses on the micro-groove preparation and its related quality analysis. Three different types of grooves, checkerboard, annular and arc, are designed for ceramics grinding experiments, accompanied with comprehensive analysis of the grinding forces, surface roughness and SEM topography. The results show that the LAG process could substantially improve the grinding surface quality and reduce the grinding force compared with the traditional grinding method. From the surface groove geometry and scratching experiments, the annular groove has proved to have a better surface integrity under a lower grinding force. Combined with the scratching analysis, it is suggested to prepare curved surface groove at a lower distance gap will more directly help to improve the grinding efficiency and surface integrity.

Contact force plan and control of robotic grinding towards ensuring contour accuracy of curved surfaces

Curved parts in the industry have characteristics of large curvature variance and small error allowance, which makes it difficult to control material removal accuracy during the compliant grinding process. Existing studies mainly focused on controlling material removal accuracy by using constant contact force or pressure strategies, while there is no force plan study that takes the material removal as a direct target in the compliant grinding process. In order to ensure contour accuracy of curved surfaces, this paper proposes a novel contact force plan and control method of robotic grinding by taking the accurate material removal at different position of the workpiece as a direct target. First, a material removal model which considers contact force, spindle speed, contact speed and workpiece curvature is proposed. Then the contact force is planned in order to guarantee material removal requirement at different point of the workpiece. Finally, in order to track the planned force with the two degrees of freedom (DOF) smart end-effector, a 2-DOF force-position hybrid control algorithm is proposed. The proposed force plan and control method are verified by simulation and grinding experiments. The results show that the proposed method has higher and uniformer contour accuracy compared with the traditional grinding method using constant force strategy.

Efficacy of a novel bone preprocessing method for better DNA yield

In cases involving identification of missing persons, mass disasters and ancient DNA investigations, bone and teeth samples are often the only, and almost always the best, biological material available for DNA profiling. Standard methods for extraction of DNA from such samples involve grinding of the bone and teeth samples. Here, we present an extremely efficient protocol for recovery of DNA from bone samples by a method of scrapping. The study was carried out on 25 samples and it was found that the quantity of DNA isolated by the scrapping method was up to 1.131 ng/µl with a success rate of 93% as compared to a much lower yield of 0.359 ng/µl DNA isolated with a success rate of 28% through the grinding method. The scrapping method of DNA extraction has been proven to be extremely useful in forensic examination of challenging samples that had multiple failures using the traditional grinding method.

Beneficiation of ponded coal ash through chemi-mechanical grinding

Four samples of low quality ponded coal ash were subjected to a chemi-mechanical beneficiation technique to test improvements to traditional grinding methods. The addition of water into this beneficiation process can further increase the reactivity of the subjected materials. Changes to the reactivity of these ponded ashes and their structure were analyzed utilizing ATR spectroscopy, X-Ray Diffraction, and Scanning Electron Microscopy. The results show a drop in structural order, smaller particle size, and a 7 to 70 percent increase in amorphous content. These improvements are in contrast to an increase in crystallinity observed with the more traditional dry grinding technique. ATR IR spectroscopy confirms the formation of additional terminal silanol groups after the chemi-mechanical grinding process suggesting a further increase in pozzolanic reactivity. These results suggest that the proposed modification to the beneficiation process does not interfere with the ash improvements observed with traditional grinding but further improves the ash reactivity due to the formation of additional silanol groups. Additionally, ponded ashes (being hydrated) are the ideal source material for this beneficiation process, allowing for a larger quantity of this material to be reutilized efficiently.

Studies of the composition of the cryogenic ground chaga

The paper studies the properties and chemical composition of birch fungus - Chaga, which contains a unique complex of biologically active substances and is used as a raw material for the production of drugs and biologically active additives. The components listed prove their antioxidant, immunomodulating, antiviral, antidiabetic, and cytotoxic properties. The paper specifies the application of chaga in such areas as medicine, agriculture and food industry. It analyses the way the method of grinding of plant raw materials might influence the quality of the resulting drugs, including the sustaining the biological activity. The results determined that the cryogenic grinding of chaga, which allows to preserve valuable substances of the fungus due to its grinding at low temperature in liquid nitrogen to be the most reasonable. The paper gives the analysis of the obtained dispersed phase by high performance liquid chromatography and atomic absorption spectroscopy. The results of the studies indicate an increase in the content of particular valuable components of the fungus in extracts of raw materials that have gone through the cryogenic grinding, compared with the extracts of raw materials obtained by the traditional grinding method. The data acquired can be of practical importance when chaga is used in medicine.

Mechanical grinding method of multi-axis linkage for elliptic contour based on algebraic geometry

Aiming at the shortcomings of traditional elliptic contour grinding methods, such as large grinding roughness and poor contour accuracy, a multi-axis mechanical grinding method based on algebraic geometry is proposed. This method studies the first attempt of elliptic contour. The process includes selecting suitable multi-axis grinding tools and selecting appropriate grinding methods according to grinding process. Using specific workpieces, grinding path planning, motion attitude determination and error compensation based on algebraic geometry for multi-axis mechanical grinding are carried out. The results show that compared with the traditional grinding method, the device has the smallest surface roughness, the contour radian is closer to the expected results, and has higher performance, which solves the grinding defects.

Experimental study of metal ceramic (WC-Co) micro-tool fabrication by controlled inclined grinding (CIG)

As a kind of metal ceramic material, cemented carbide (WC-Co) has attracted attentions of many scholars for its excellent material property. In this paper, a new method named controlled inclined grinding (CIG) is proposed to fabricate a micro-substrate of cemented carbide. The machining mechanism during CIG was investigated; a lot of micro-substrates, whose diameter is from 8 to 120 μm, had been successfully fabricated; and the critical parameters for obtaining the suitable machining result are given. Two ultra-small micro-tools, with a diameter of 8 μm and 20 μm, respectively, and an aspect ratio (for both) of bigger than 50, had been fabricated by the CIG method. The relationship between tool contour and inclined angle (θ) was revealed, and the optimal inclined angle was found to be 0.5°. Differences when grinding at different wheel positions were studied and compared, and an optimal grinding position was found. A contrast experiment was designed and carried out by using the CIG method and traditional grinding method, and machined workpiece surface was observed by a profilometer and a scanning electron microscope (SEM); it is found that the machined surface of the CIG method was comparatively gentle and even, while the machined surface of the traditional method was violent and uneven. A surface roughness model for the CIG method was built, the corresponding expression was derived, and the surface roughness model was finally validated experimentally. The CIG method proposed in this study is not only a simple device but also cheap and efficient, and it is anticipated to be an optional method to fabricate micro-tool.

Improving quality of cumin powder through cryogenic grinding technology

Cumin (Cuminum cyminum L.) seeds contain numerous phytochemicals. A study was conducted to evaluate the effect of cryogenic grinding over traditional grinding method of cumin seeds so as to determine the optimum grinding condition for high quality cumin powder. Effect of cryogenic grinding at varying temperatures (−30 to 10 °C and ambient), feed rates (5 to 7 kg/hr), and sieve size (0.8 to 1.5 mm) were evaluated with respect to mean particle size, grinding time, and volatile oil content. It was found that cryogenic grinding retained 62.56% more volatile oil as compared to ambient grinding. On the basis of retention of volatile oil, the premium quality cumin powder was obtained at grinding temperature −30 °C with a feed rate of 7 kg/hr and sieve size of 0.8 mm. The storage study of cryo-ground cumin powder confirmed that refrigerated storage had advantage over ambient storage in terms of freshness and volatile oil for longer periods. Cryo-ground cumin powder retained 3.3% volatile oil which contained 29.61% cuminaldehyde and 5.36% γ-terpinene along with other compounds. Practical applications Cryo-ground cumin powder retained more volatile oil which improves the quality of ground cumin powder. Cryo-ground cumin powder has higher market value thus, more profit to processors and high quality product to consumer. The study revealed the importance of cryogenic grinding of valuable spices to retain its freshness and organoleptic qualities.

Determining the Effect of Process Control Parameters on Tool - Chip Interface Temperature during Hard Turning of AISI D3 Tool Steel in Dry Condition

Hard turning is recent upcoming technology through which surface quality of machined components can be enhanced while comparing with the traditional grinding method. Since the absence of metal cutting fluids during this process, numerous harmful effects on shop floor operators and possible negative impacts on environment can be eliminated. Normally some of the vital machinability aspects such as surface integrity of machined parts has been influenced by magnitude of cutting temperature which evolved in metal cutting interface. Therefore in this experimental investigation, the influence of various process control parameters on tool-chip interface temperature was evaluated during hard turning of AISI D3 tool steel in dry condition. The machining trials were conducted as per the L9 Taguchi DOE approach and subsequent experimental data were analysed with the use of Design-Expert® V7 statistical software. This experiment results revealed that feed rate is having predominant influence in determining the magnitude of cutting temperature followed by depth of cut and cutting speed whereas the influence of cutting tool nose radius is insignificant.

Precision Machining Based on Elastic Waves in Solids

A grinding tool without kinematic pairs, of compactness and low cost, based on the defect that it is difficult to improve the precision of kinematic pairs of traditional grinding methods, is presented in the paper. The operating principle based on elastic waves was analyzed. The grinding tool would realize the ultra-precision machining theoretically and experimentally. Components of the prototype were manufactured, assembled, and tested for the grinding performance to validate the concepts of the precision machining and confirm the simulation results of modal and harmonic analysis. The test results show that the performance of the proposed grinding tool can meet the requirements of the precision grinding. It is confirmed that this prototype can realize the accurate ultra-low-stress and the removal of material under ultra-low-stress circumstance. The research is aimed at exploring new methods and new theories of ultra-precision surface machining and giving a new solution to the problem of ultra-precision surface machining.

Finite Element Modeling Method of 3D Braided Composites Based on ICT Technique

A finite element modeling method based on industrial computed tomography (ICT) technique is proposed to address the insufficient accuracy of traditional grinding method for the meso-structure analysis of composite materials. In this method, the slice images of 3D composites are first acquired by ICT technique. And then, the internal meso-structure images of composite materials are obtained through the digital image processing to the slice images. Finally the meso-structure images are converted to vector format and inputted ANSYS to build the finite element model for the analysis of the mechanical properties. The experimental results show that this method can establish the finite element model and reveal the internal structure and the inherent mechanical properties of composite materials. These researches provide a reference for the manufacture processing of 3D braided composites, and the theoretical basis for the optimal design and performance evaluation. It would be of significance for the improvement of the composites mechanical properties.

Comparison of the shaping ability of Twisted Files with ProTaper and RevoS nickel-titanium instruments in simulated canals

Background/purposeThe manufacturer claims that Twisted Files (TFs) are superior to file systems made by the traditional grinding method due to their cyclic fatigue resistance, flexibility, and better cutting efficiency. The aim of this study was to compare the shaping ability of TFs with instruments produced by a traditional NiTi grinding process (RevoS and ProTaper). Materials and methodsA total of 60 simulated resin blocks were divided into three experimental groups, each comprised of 20 resin blocks that were prepared with TFs, RevoS, and ProTaper using a crown-down technique. The preparation shape was assessed with a computer image analysis program on superimposed pre- and postoperative images. Material removal was measured at 10 points beginning 1 mm from the end-point of the canal. Mean total widths and outer and inner width measurements were determined on each central canal path, and the data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U-tests. ResultsThe Revo-S and ProTaper instruments removed more material from the inner side of the curvature compared with the TF instruments. Differences among the three rotary NiTi systems were statistically significant (P < 0.05) except for the first 3 mm and the last 2 mm. On the outer side of the canal, both the ProTaper and Revo-S instruments removed more material than the TF instruments in the apical third (P < 0.05). ConclusionAccording to the results of this study, TFs respected the original canal curvature better than did ProTaper and RevoS rotary NiTi instruments. TF instruments also provided a more-centered apical preparation of the simulated canals at the apical third.

Grinding characteristics of diamond film using composite electro-plating in-process sharpening method

To finish a chemical vapor deposition (CVD) diamond film surface, composite electro-plating is introduced during the grinding process to sharpen the grinder, a method named as composite electro-plating in-process sharpening (CEPIS). In the grinding process, the grinder for the cathode and the nickel plate for the anode are connected to a DC power supply and immersed in an electrolyte solution containing diamond particles of 10 μm in size so that metal ions with diamond particles are deposited onto the grinder in process to expose fresh sharp grains. Results show that the removal rate of the diamond film increases with increasing current density. The removal rate of the diamond film at a current density of 7.5 ASD is 3.8 times higher than at 0 ASD as in the traditional grinding method. Based on the experimental results of the observations of the coated surface of the grinder and the variations in the coating thickness, a sharpening mechanism for the CEPIS method is deduced. This mechanism allows the coating thickness of the grinder to be increased with grinding time using the CEPIS method. The higher removal capability is achieved due to the higher active grit density.

Reducing the surface roughness in grinding

Reducing the surface roughness in grinding

Enhanced antioxidant bioactivity of Salvia miltiorrhiza (Danshen) products prepared using nanotechnology

The traditional Chinese medicine, Salvia miltiorrhiza (Danshen), promotes blood circulation and relieves blood stasis, also demonstrating good antioxidant activity. In the present study, therefore, the antioxidant activities of medicinal plant materials prepared using nanotechnology or traditional grinding methods were compared using three biological assays. It was found that the nanotechnology preparation had stronger antioxidant bioactivities. Complementary quantitative analysis of four active constituents, salvianolic acid B, cryptotanshinone, tanshinone I and tanshinone IIA, by HPLC revealed only marked differences for salvianolic acid B. The results indicate that the polar active constituent in the nanotechnology samples was released faster compared to the traditionally powdered samples.

A direct comparison of the performance of ground, beaded and silica-grafted MIPs in HPLC and Turbulent Flow Chromatography applications

Spherical molecularly imprinted polymers (MIPs) specific to the β-blocker propranolol have been synthesised using two different approaches and compared to traditional ground monolithic MIPs in HPLC and TFC applications. TFC is a LC technique used for rapid extraction of compounds directly from complex matrices. It can be easily coupled to HPLC and MS for automation of an extraction/analysis procedure. Spherical MIP beads were produced using a suspension polymerisation technique and silica/MIP composite beads by grafting MIP to spherical silica particles using a surface-bound initiator species. Synthesis of both beaded and silica-grafted MIPs was more practical than using the traditional grinding method and yields of spherical particles of the required size between 80 and 100% were routinely achieved. Under HPLC conditions, beaded and ground MIP materials showed a degree of chiral separation for all of the nine β-blockers tested. The beaded MIP, however, showed much better flow properties and peak shape than the ground material. Silica-grafted MIP showed some separation in five of the drugs and a large improvement in peak shape and analysis times compared with both ground and beaded MIPs. The materials prepared were also used in extraction columns for Turbulent Flow Chromatography (TFC). Although no imprinting effect was observed under typical TFC conditions, beaded polymer materials showed promise for use as TFC extraction columns due to the good flow properties and clean extracts obtained.