Dry High Speed Research Articles

Prediction of the Modal Parameters of The Spindle System in High-speed Dry Hobbing Machine with Thermal Effects

High-speed dry hobbing is an advanced green machining technology for gears. However, thermal issues in the machine tools become serious under the high cutting speed and dry cutting conditions, which result in a nonlinear evolution of the machine tool dynamics, and finally affect the hobbing stability. In view of this, introducing the hob spindle system as the object, this paper intends to investigate the influence of time-varying temperatures on the modal parameters based on the modal tests. Then, a temperature-dependent modal parameters prediction model based on the multi-output Gaussian process regression (MOGPR) is proposed. The experimental results indicated that the modal parameters of the spindle system vary obviously with changing thermal states. The natural frequencies for the first and third modes increased with the temperature rise, while the variation of the natural frequency for the second mode was insignificant. The damping ratios for the first three modes showed a decreasing trend with the temperature rise. The constructed MOGPR model has the capability to effectively predict the modal parameters with the time-varying thermal effects, which can provide a support to build the temperature-dependent hobbing stability boundaries.

Thermal-field analytical modeling of machined surface layer in high-speed-dry milling UD-CF/PEEK considering thermal anisotropy and nonlinear thermal conductivity

The high-speed-dry (HSD) machining is now recognized as a strong potential dry-cutting technique to tackle the rapidly growing productivity demand of carbon-fiber-reinforced-polyetheretherketone (CF/PEEK). The thermal-field is an essential breakthrough for eliminating the severe thermal effect of cutting temperature beyond CF/PEEK glass transition temperature Tg. However, the anisotropy and temperature-sensitive thermal conductivity of CF/PEEK lead to great challenges in thermal analytical modeling. Addressing this issue, a novel thermal-field analytical model that incorporates fiber orientation-dominated thermal anisotropy is developed to investigate the thermal field of machined surface layer for unidirectional (UD) CF/PEEK HSD milling, where the nonlinear thermal conductivity of CF/PEEK are imported into this model. With experiment verification, the thermal-field model can forecast the spatio-temporal distribution of workpiece temperature. Then, the thermal mechanisms of fiber orientations and milling parameters are clarified to restrict workpiece temperature within the Tg for limited thermal damage and reveal the feasibility essence of CF/PEEK HSD milling.

EVOLUTION AND DISTRIBUTION OF SHAKES IN LARCH LOGS DURING AIR DRYING

This paper analyzed the length, width, and location of shakes in the air-drying process of larch log (Larix principis-rupprechtii Mayr) 1 m long and 66% initial moisture content. The development law and distribution characteristics of shakes during log drying of larch were studied and shake generation and development law were analyzed from two aspects of microstructure and growth defects. The variation of dry shrinkage deformation along the radial direction and knot influence on it was analyzed using the split-shaped stress test strips. At the cellular level, the cell wall shrinkage behavior of heartwood and sapwood and the microstructure of knots were observed. The results showed a significant relationship between eccentricity and shake distribution; the IIa region is the most prone to dry shake. The evolution of shakes is closely related to the drying rate. In the high-speed drying stage (MC ≥ 40%), shakes almost do not occur; in the decelerating drying stage (40% ≥ MC ≥ 20%), the amount, length, and width of shakes increase rapidly. In the low-speed drying stage (20% ≥MC), the area of shakes tends to stabilize or even decline. The main reasons for dry shaking are the dry shrinkage difference between tangential and radial cell walls, early and late wood, heartwood and sapwood, and moisture content gradient during the drying process.

Investigation on Geometrical Morphology of Tooth Surface Finished by Green High-Speed Dry Hobbing for Gear Precision Machining

Investigation on Geometrical Morphology of Tooth Surface Finished by Green High-Speed Dry Hobbing for Gear Precision Machining

Improving Sustainability Index of Grey Cast Iron Finish Cutting Through High-Speed Dry Turning and Cutting Parameters Optimization Using Taguchi-Based Bayesian Method

Improving Sustainability Index of Grey Cast Iron Finish Cutting Through High-Speed Dry Turning and Cutting Parameters Optimization Using Taguchi-Based Bayesian Method

Surface roughness prediction model in high-speed dry milling CFRP considering carbon fiber distribution

The surface roughness of carbon fiber-reinforced polymer (CFRP) components is extremely important because of the increasing demand for higher performance, reliability, and longer lifetime in aerospace and other manufacturing industries. However, the cutting mechanisms of CFRP are still unclear, which limits its formation mechanism prediction for surface roughness. Thus far, this study presents three action mechanisms in the CFRP machining process: accumulation bouncing on the matrix, impact effect on carbon fibers, and workpiece self-action. The workpiece self-action was reflected and calculated using the light rope model, which is new in CFRP machining. Furthermore, the formation mechanisms of surface roughness were first elucidated in the high-speed dry (HSD) milling of CFRP. An accurate surface roughness prediction model was theoretically formulated considering the kinematics, dynamics, and carbon fiber distribution. Surface roughness was expressed as the three-dimensional arithmetic mean height. The surface roughness prediction model was established and confirmed to have a high prediction accuracy of 90.05%, demonstrating that the distribution of carbon fibers was the main influencing factor of the surface roughness. Moreover, nonlinear regression analysis was used to clarify the effects of cutting parameters on the surface roughness, impact effect, and relationship between the surface roughness and impact effect. The study verified the feasibility of HSD milling CFRP, and it also provided guidance for breaking the low-speed machining limits by improving the machining process.

Specific cutting energy optimization of CF/PEEK milling considering size effect

As the radius of carbon fibers and cutting edge are in the same order of magnitude, workpiece self-action, which could not be neglected in machining Carbon Fiber Reinforced Polymer (CFRP) considering size effect, has become a new perspective. Specific Cutting Energy (SCE) is a significant indicator for chip formation, cutting forces, tool wear, and machined surface integrity. Based on this, we presented a light springs model to clarify workpiece self-action to establish a specific cutting energy (SCE) prediction model of high speed dry (HSD) milling CFRP. The light springs model, which was also a direct reflection of the size effect, reflected the interaction of carbon fibers, interfaces and the matrix. The carbon fibers distribution in the chip was counted to confirm the light springs deformation at different position as carbon fiber and interface are consisted of the light spring. First of all, based on workpiece self-action and elastic-plastic theory, the cutting mechanisms were clarified to calculate SCE with high prediction accuracy (maximum relative error 7.7%). Furthermore, SCE distribution was obtained based on different cutting mechanisms, including bending, stretching, delamination and pressing bouncing. To improve machined surface integrity, three-dimensional (3D) arithmetic mean height and 3D fractal dimension were used for quantitative characterization of the surface integrity. The paper defined integrated evaluation indexes SCEDS and SCESa to reflect effective SCE to optimize milling parameters based on correlation analysis of SCE distribution and surface quality, founding that HSD milling operation could reduce machining defects.

Effect of High-Speed Dry Face Milling on Surface Integrity Characteristics of AZ91 Mg Alloy

Effect of High-Speed Dry Face Milling on Surface Integrity Characteristics of AZ91 Mg Alloy

Effects of Zeolites and Carboxymethyl Cellulose Molecular Weights on the Quality of Coating Color and Inkjet Paper

The study aim was to develop a technology that can improve the quality of inkjet paper while reducing the production cost. Silica has so far been the most promising and suitable pigment for inkjet paper. However silica has limitations such as high price, high viscosity and flow characteristics that prevent high-speed drying. A previous study reported that zeolites can partially replace silica to produce inkjet paper. The drawback of replacing silica with zelolites is that the viscosity of the coating color is lowered, which generates other issues in the coating color and manufacture of inkjet paper. For this reason, carboxymethyl cellulose (CMC) was used as a thickener to control the coating color viscosity. the effect of molecular weight and addition amount of CMC added to the coating color using zeolites on the rheological behavior of the coating color with zeolite. Addition of CMC improved the viscosity and flow characteristics of the coating color. Additionally, the physical properties excluding optical properties, and smoothness of the manufactured inkjet paper were improved.

Surface integrity optimization of high speed dry milling UD-CF/PEEK based on specific cutting energy distribution mechanisms effected by impact and size effect

Carbon fiber-reinforced polymer (CFRP) composites have been widely used in the aerospace industry due to their excellent mechanical properties. Cutting mechanisms of machining CFRP and its effect on machined surface integrity are still unclear due to inhomogeneity and anisotropy. To this end, this paper studied the cutting mechanisms of CFRP by establishing an impact-based Specific Cutting Energy (SCE) distribution prediction model of high speed dry (HSD) milling CFRP which is be an effective and eco-friendly cutting method. SCE is divided into five sub-SCEs affected by shearing, pressing, impacting, bouncing and delamination, respectively. Among them, sub-SCEs generated by pressing and impacting are influenced by carbon fiber distribution due to size effect and material properties, carbon fiber distribution model was introduced into the SCE prediction model. The proposed model was verified with maximum relative error 7.6%, demonstrating that impact and size effect are of great significance in revealing the cutting mechanism of CFRP. To clarify the effect of SCE distribution on surface integrity, three-dimensional (3D) arithmetic mean height and 3D fractal dimension were used to quantitative characterization of the surface integrity and sub-SCEs are diagnosed for obtaining the way of sub-SCE distribution effecting surface integrity by correlation analysis. According to SCE diagnosis, the milling parameters are optimized by removing sub-SCEs unrelated to surface integrity, founding that HSD milling can reduce machining defects.

Process optimization of high machining efficiency and low surface defects for HSD milling UD-CF/PEEK with limited thermal effect

Carbon fiber reinforced polyetheretherketone (CF/PEEK) is widely applied in aerospace and medical fields due to its excellent strength-to-weight ratio, fatigue resistance and biocompatibility. However, traditional dry machining significantly limits the improvement of machining efficiency and surface quality. Addressing this issue, this paper proposes a process optimization method of high machining efficiency and low surface defects for high-speed dry (HSD) milling UD-CF/PEEK, based on analyzing the thermal effect of cutting temperature. Mixed-level orthogonal experiments are designed for dry milling unidirectional (UD) CF/PEEK laminates with the fiber orientation of 0° and 90°. Three-dimensional surface roughness Sq, cutting temperature Tc and material removal rate MRR are extracted to characterize experiment results. The results show that the cutting temperature is mainly affected by cutting speed and fiber orientation, and machined surface defect is mainly caused by the thermal effect of high cutting temperature. Then, a process optimization model of high machining efficiency and low surface defects is established based on the genetic algorithm optimized BP (GA-BP) neural network, non-dominated sorting genetic algorithm (NSGA-II) and technique for order preference by similarity to an ideal solution (TOPSIS). The optimization objectives are Sq, MRR and Tc, and Tc also serves as a constraint of the thermal effect. Verification experiments are carried out, and results reveal that the surface defects are significantly reduced by limited thermal effect, and the model can be used to effectively improve machining efficiency and surface quality for HSD milling UD-CF/PEEK. Besides, the material removal rate generated by the HSD milling operation can easily reach 2–3 times higher than the traditional low-speed dry milling operation. The optimized cutting speed in HSD milling UD-CF/PEEK is recommended as 1300–1600 m/min. This study provides significant technical guidance for the machinability improvement of HSD milling UD-CF/PEEK in practice.

A force model of high-speed dry milling CF/PEEK considering fiber distribution characteristics

Carbon fiber reinforced polyetheretherketone (CF/PEEK) is an emerging material that is widely used in the automotive and aviation industry due to its high shock resistance, thermostability, and recyclability. However, its dry-machining requirement with an unclear dynamic material removal process limits the machining efficiency and surface quality. To this end, we firstly established a two-dimensional joint probability distribution model of cutting carbon fibers based on the microstructure of CF/PEEK. Compared with previous brittle models, the plastic model is verified to be more consistent with experimental results. A high-speed dry (HSD) milling force model considering carbon fiber distribution is then developed and is proofed with a high prediction accuracy of about 92.6%. With the proposed model, the milling force can be separated into forces of cutting carbon fibers and PEEK matrix, by which the influences of high-speed dry milling process on carbon fibers and PEEK matrix can be analyzed. The results show that carbon fiber distribution exhibits a significant impact on milling force and is more easily affected by milling parameters compared with the PEEK matrix. It is also verified feasible to HSD milling CF/PEEK, and the work gives the guidance of breaking the low-speed machining limits by improving the machining process.

Process optimization of high-speed dry milling UD-CF/PEEK laminates using GA-BP neural network

High-performance carbon fiber-reinforced polyetheretherketone (CF/PEEK) is widely used in aerospace and premium-end medical fields due to its high strength-weight ratio, shock resistance, and reusability. However, its dry machining requirement is a significant limit to improving machining efficiency and machining quality using a traditional process. Addressing this issue, the high-speed dry (HSD) machining technique is imported in this paper. Multi-level mixed orthogonal experiments of dry milling unidirectional (UD) CF/PEEK laminates with the fiber orientation of 0° and 90° are designed. Aiming at quantitative characterizing surface quality, three-dimensional (3D) surface roughness Sq and 3D fractal dimension Ds are used to present surface roughness and surface defects, respectively. A characterization system for surface defects generated in milling CRF/PEEK is proposed. A prediction model of surface quality considering fiber orientation, cutting speed, feed per tooth, and cutting width is then established using the genetic algorithm optimized BP (GA-BP) neural network. The prediction results show that the model is of acceptable generalization capability with a prediction accuracy of over 90.39%. Based on the analysis of surface qualities and cutting temperatures, the HSD machining technique is verified to be feasible in milling UD-CF/PEEK, and the recommended cutting speed in the HSD milling boundary is 1500–1600 m/min. The 3D fractal dimension is verified feasible to evaluate the size of complex surface defects of the machined UD-CF/PEEK. It has a non-rigid negative correlation with Sq in general. Besides, cutting speed and fiber orientation are the key factors affecting the machined surface microstructural characteristics. The present study gives technical references for improving surface quality in HSD milling CF/PEEK.

Multi-objective Optimization and Decision-making Method of High Speed Dry Gear Hobbing Processing Parameters

Multi-objective Optimization and Decision-making Method of High Speed Dry Gear Hobbing Processing Parameters

Influence of probe geometry in micro-scale impact testing of nano-multilayered TiAlCrN/NbN coatings deposited on WC-Co

Hard nano-multilayered TiAlCrN/NbN coatings on cemented carbide have shown promise in dry high speed machining applications involving repetitive contact, such as end milling of hardened H13 steel. In this study the fracture resistance of TiAlCrN/NbN coatings under repetitive dynamic high strain rate loading has been evaluated by the micro-scale impact test method. Although the fatigue mechanisms can vary with the ratio of coating thickness t to the indenter radius R, macro-scale tests of thin coatings using probe radii in the mm range are necessarily at low t/R. Micro-impact tests at higher t/R have been performed with a range of diamond indenter geometries (R = 8, 20, 100 μm) to investigate the role of varying t/R (0.03–0.375) on the deformation behaviour. With the largest radius probe there was no clear failure for the coatings or substrate under the test conditions. With the 8 and 20 μm radius probes the behaviour of the coatings was strongly load-dependent and they were more susceptible to impact-induced damage than the carbide substrate. As the load increased there was a change from coating to substrate dominated deformation behaviour as the stress field extended further into the substrate. At lower load the dominant fracture behaviour was coating fracture through ring cracking, radial cracking and chipping. At higher load chipping became less prevalent and break-up of the carbide substrate more extensive.

Taguchi parametric study on the radial and tangential cutting forces in Dry High Speed Machining (DHSM)

In this paper, L8 Taguchi array is applied to find the most important parameters effects on the radial and tangential cutting forces of a Ti–6Al-4V ELI titanium alloy in dry high speed machining (DHSM). The experiments are performed in four cutting speeds of 150, 200, 250, and 300 m/min and two feed rates of 0.03 and 0.06 mm/rev. Also, two cutting tools in types of XOMX090308TR-ME06 of uncoated (H25) and TiAlN+TiN coated (F40M) are used. Results confirm that to minimize the resultant cutting force and radial cutting force, utilizing the lower feed rate and higher cutting speeds were considered as the best levels of factors to reach to its goal.

Friction and Wear Characteristics of 18Ni(300) Maraging Steel under High-Speed Dry Sliding Conditions.

18Ni(300) maraging steel, which has exceptional strength and toughness, is used in the field of aviation and aerospace. In this paper, using a high-speed tribo-tester, tribological behaviors of 18Ni(300) maraging steel were investigated under high-speed dry sliding conditions. Morphology of the worn surfaces and the debris was analyzed by scanning electron microscope, and the oxides of worn surfaces caused by friction heat were detected by X-ray diffraction. The experiment results reveal that the friction coefficient of frictional pairs declines with increasing load and speed. With the speed and load increasing, oxides of the worn surfaces of 18Ni(300) maraging steel change from FeO to Fe3O4 and the wear mechanism converts from adhesive wear into severe oxidative or extrusion wear.

Encapsulated of Red Beet Colour Changes During Spray Drying

In this research, the red beet concentrates were encapsulated with maltodextrin (DE10) citric acid, monoglycerides, lecitin and sunflower oil then spray dried at 150, 160, and 170°C. The color of each spray dried powder was diluted to one brix and analysed by spectrophotometer at 510 nm in duplicate which was compared to initial color of concentrated red beet. The deterioration of color loses were behaved first-order reaction and the reaction rates (k) were determined as 0.02, 0.039 and 0.068 sn-1 at 150, 160, and 170°C respectively. Higher spray drying air temperature results in high-speed drying. However, it was determined that high inlet air temperatures caused more pigment loss. From reaction rates the activation energy was estimated about 21.16 Kcal/mol by using of Arrhenius equations. Determined during the degradation of pigments by heat, t1/2 values were found as 31.25 sec, 17.76 sec, 10.01 sec at 150, 160, and 170°C, respectively. It was determined that the color of red beet was so sensitive during spray drying. It was also determined that reaction rate was about two times faster at each drying temperature raise up 10°C, it was also size of the encapculated powder were determined between 1-10 µm by scanning electron microscope.

Tool wear and chip formation during dry high speed turning of direct aged Inconel 718 aerospace superalloy using different ceramic tools

Direct aged Inconel 718 superalloy is used in manufacturing critical cross-sections of aero-engine components. It is a hard-to-machine material, especially in dry conditions. To perform successful machining operations for this alloy, cutting tools with high hot hardness and chemical stability are required. The present study investigates the tool wear and chip formation during dry finish turning of direct aged Inconel 718 superalloy (51–53 HRC) using different ceramic tools. Pure alumina with added ZrO2 and alumina matrix reinforced with silicon carbide whiskers tools were used at cutting speeds of 150 and 250 m/min. A scanning electron microscope and energy dispersing spectroscopy were utilized to study the tool wear mechanisms. Structural and phase transformations during cutting on the tool–chip interface at the higher cutting speed were analyzed with X-ray photoelectron spectroscopy. Chip-undersides and cross-sections were studied with scanning electron microscope to investigate the chip formation mechanism. Results reveal that pure alumina with added ZrO2 can be an adequate choice for machining direct aged Inconel 718 because of its higher abrasive wear resistance and the formation of a sapphire protective tribo-layer at the tool–chip interface under severe cutting conditions. Chipping and notching of the cutting edge was found to decrease with the rise of the cutting speed for this tool material. As confirmed by X-ray photoelectron spectroscopy, alumina reinforced with silicon carbide whiskers tool was found to have a lower performance due the chemical degradation of the whiskers, especially at the higher cutting speed (250 m/min).

Low-Cost Dual-Mechanical-Port Dual-Excitation Machine for Washing Machine Application

This paper proposes a low-cost dual-mechanical-port dual-excitation machine for washing machine application. The proposed machine artfully combines two machines (vernier and permanent magnet synchronous machine (PMSM)). An outer vernier rotor is used for the low-speed washing operations, and an inner PMSM rotor is used for the high-speed drying operations of the washing machine. The proposed machine is compared with a similar recently presented machine to verify its cost-effectiveness. Comparison using the finite element analysis (FEA) shows that the ferrite magnets used in the proposed topology are more cost-effective. Furthermore, compared to the existing machine, the power factor of the proposed machine is high during the drying operation; hence, a lower rating inverter is sufficient to drive the machine, which further reduces the overall cost. In addition, the proposed machine provides similar efficiencies as the existing machine for both washing and drying operations.