Hollow Parts Research Articles

Simultaneously improving the resolving power and sensitivity for planar high-field asymmetric waveform ion mobility spectrometry using a mixed gas inlet mode at two ends.

Resolution and sensitivity are two key parameters for describing the performance of high-field asymmetric waveform ion mobility spectrometry (FAIMS). An increase in the resolving power of FAIMS has been realized by adding helium to nitrogen in planar FAIMS, but it comes at the expense of sensitivity. Here, a new hollow needle-to-ring discharge device integrated on a PCB substrate is used as the ion source for FAIMS. Helium flows from the hollow part of the hollow needle to improve the ionization effect. Nitrogen carries the sample into the ionization chamber and is mixed with helium as the carrier gas. Under a nitrogen flow rate of 1L min-1 , 1.5L min-1 , 2L min-1 , and 2.5L min-1 , adding helium at different flow rates (0.2L min-1 , 0.3L min-1 , 0.5L min-1 , and 1L min-1 ) can simultaneously improve the separation ability and sensitivity. Helium and nitrogen with flow rates of 0.2, 0.3, 0.5, and 1L min-1 were added to nitrogen (2L min-1 ). The separation ability and sensitivity of the mixed gases doped with helium are better than those of nitrogen. The larger the RF voltage amplitude is, the more obvious the improvement in the separation ability when helium is added. However, helium doping has the opposite effect on the sensitivity. This study provides a new idea and technical means for the application of helium and nitrogen gas mixtures in planar FAIMS. This method can greatly improve the performance of FAIMS.

A compound plume with solid and hollow parts formed downstream of an argon plasma jet at atmospheric pressure

Plasma jet is able to produce abundant active species in plasma plume, whose morphology is a key issue for its various application fields. In this paper, we report the first observation of a compound plume with a solid part and a hollow one in an argon plasma jet. Results indicate that the compound plume can only be formed under proper conditions. Integrated emission waveform reveals that the compound plume initiates with periodicity. By fast photography, it is found that after a passage of straight-line propagation, some positive discharges behave as a curved propagation due to the influence of residual ions. Moreover, the solid part comes from negative discharges and the straight-line propagation of positive discharges. In contrast, the hollow part originates from the curved propagation of positive discharges. Optical emission spectroscopy verifies the existence of residual ions. These results can enrich the morphology of plasma plume.

УДОСКОНАЛЕННЯ ПРОЕКТУВАННЯ ТЕХНОЛОГІЧНОГО ПРОЦЕСУ ТОЧНОГО ОБ’ЄМНОГО ШТАМПУВАННЯ ВИДАВЛЮВАННЯМ НА ОСНОВІ РОЗВИТКУ ЕНЕРГЕТИЧНОГО МЕТОДУ БАЛАНСУ ПОТУЖНОСТЕЙ

Improvement of technology design in precision forging process based on development of energy method with power balance and development of recommendation with the rational use of systematized based on kinematic modules in complex configuration to make calculated schemes for power mode assessments and shaping of part in cold forging extrusion process with subsequent software implementation are considered. Methodology. Energy method of power balance is considered based on kinematic module method that will be systematized the results of investigation for expanding in cold forging extrusion process with the definition of the power mode in deformation and features of semi-finished product shaping to make hollow and rod parts with flange such as sleeves and glasses. Results. Development results of recommendation with the rational use of systematized based on kinematic modules in complex configuration to make calculated schemes including with the ability to quickly take into account changes in the configuration of the tool have been determined. This made it possible to define the several factors for controlling the shaping of the semi-finished product in combined and sequential combined cold forging extrusion processes. Scientific novelty. Energy method of power balance is considered such as an effective method of preliminary analysis to determine the area of rational use in cold forging process based on process technology design to make complex parts. Practical significance. Software product development with extended systematization based on kinematic modules, complex of calculation models in cold forging extrusion with power mode assessments and to predict shaping of part and defect formation such as dimple defect will contribute more active implementation in the manufacturing industry for combined cold forging extrusion processes.

On the relationship between cutting forces and anisotropy features in the milling of LPBF Inconel 718 for near net shape parts

The versatility and potential applications of additive manufacturing have accelerated the development of additive/subtractive hybrid manufacturing methods. LPBF processes are exceptionally efficient at producing complex-shaped, thin-walled, hollow, or slender parts; however, finishing machining operations are necessary to ensure part assembly and surface quality. Rapid solidification during LPBF processes generates columnar grain structures in alloys. This is associated with crystalline textures and anisotropy, and therefore, mechanical properties are highly dependent on space directions, thus affecting cutting force and its variability.In this study, theoretical and experimental analyses examined the effects of LPBF parameters on cutting forces and the anisotropy of alloys. Therefore, an oblique cutting Taylor based model was proposed to quantify the crystallographic effects on the shear strength. For this, the tool geometry, tool position, and laser scanning strategy were considered along with the microstructures, crystallographic textures and grain morphologies of two samples with different layer thicknesses (low-volumetric energy density (VED) and high-VED) using scanning electron microscopy and electron backscatter diffraction. Peripheral milling operations had been performed under 54 experimental conditions to evaluate the interactions between the machining parameters along with the layer thickness and the microstructural characteristics of printed alloys. The analysis revealed a significant interaction between the direction of the plane of the shear band and the grain orientation along the main axis. Three milling configurations were evaluated. The effects of the layer thickness on the evolution of the cutting force were elucidated. Additionally, the low-VED sample exhibited higher anisotropy in the cutting force compared to the high-VED one. The anisotropy in the latter corresponds to a high, dense <001> ring-like texture; however, the crystallographic effect is lower in the low-VED sample. A good correlation between the cutting force fluctuation and the predicted Taylor factor was obtained. Lastly, the grain boundary density was acceptably correlated with the level of cutting force for both the printed cases.

Tubular phononic crystal sensor

We propose the design of a tubular phononic crystal (TPC) for the purpose of sensing the physical properties of a liquid filling the hollow part of the tube. The TPC is constituted by a periodic repetition of washers along a hollow pipe with the advantage of avoiding any perturbation of a flowing fluid by any element inside the tube. Using finite element simulations, we demonstrate the existence of complete as well as polarization dependent bandgaps inside which one can design localized modes associated with defects. The most sensitive cavity to the liquid sound velocity is found to be constituted by a Fabry–Pérot (F–P) cavity. The signature of the cavity modes can be detected as peaks or dips in the transmission spectrum as well as at the external surface of the cavity. We study the dramatic effect of the liquid viscosity, more particularly shear viscosity, on these features and discuss the conditions for their practical observation. A TPC test sample made of a polymer is fabricated by means of 3D printing and characterized without the liquid by transmission measurements. The comparison with the simulations showed the necessity of considering the damping of the polymer whose effect on the transmission features is discussed. Our sensor design can find many applications at different scales in several systems transporting a fluid as microfluidic channels in micro- and nanotechnologies, syringes in medicine, or pipelines in civil engineering.

Integration of tube end forming in wire arc additive manufacturing: An experimental and numerical investigation

Integration of tube end forming operations in metal additive manufacturing routes has a great potential for the fabrication of customized features in additively deposited hollow parts. This paper is focused on the integration of tube expansion with rigid tapered conical mandrels to highlight the advantages in the construction of overhanging flares derived from the elimination of support structures and prevention of humping. The work draws from the mechanical and formability characterization of stainless steel AISI 316L tubes produced by wire arc additive manufacturing (WAAM) to the experimental and numerical simulation of the construction of overhanging flares by tube expansion. Strain loading paths obtained from digital image correlation and finite element analysis combined with the strain values at the onset of necking and fracture allow determining the critical ductile damage that additively deposited tubes can safely withstand. Results show that despite formability of additively deposited tubes being influenced by a dendritic based microstructure, their performance is adequate for tube end forming operations, such as tube expansion, to be successfully integrated in metal additive manufacturing without the need of using expensive hardware and complex deposition strategies.Graphical abstract

Hollow‐Fiber Melt Electrowriting Using a 3D‐Printed Coaxial Nozzle

Herein, a 3D‐printed nozzle designed for the single‐step fabrication of melt electrowritten hollow fibers is introduced. To achieve this, selective laser melting (SLM) is used to fabricate the outer part of the coaxial nozzle (800 μm inner diameter) from Ti6Al4V, into which a conventional nozzle (250 μm inner diameter) is inserted. Several iterations of coaxial nozzle design result in a well‐aligned inner core nozzle that delivers air into the Taylor cone of medical‐grade poly(ε‐caprolactone) (PCL). Air from this bubble forms the hollow part of the fiber while the PCL shell solidifies as the shell. The smallest PCL fibers have an approximate outside diameter of 10 μm and a lumen of 6 μm, making this a promising one‐step technique for small diameter hollow fiber fabrication.

Elimination of Non-stick on Leads Defect through Re-designed WCTP

This paper presents the reformation and fabrication resolved on the wire clamp and top plate (WCTP) design to eliminate the presence of lead finger bouncing resulting to high rejection of non-stick on leads (NSOL). Problem experienced was that the hollow or half-etched portion of the leadframe at the top and bottom units caused its bouncing effect. With the aim to improve localized massive NSOL defect, WCTP has been modified to provide positive bias to support its hollow part or the half-etched part of the leadframe at the top and bottom of the units. The re-designed WCTP was fabricated, extending its clamping with enhanced vacuum on top and bottom rows. The implementation of the improved WCTP design reduced the defect with 88 % improvement with the defect reduction during the lot runs.

Study of dependence of hardness of steel cylindrical parts on technological parameters

On the basis of the conducted experiments with the use of pressing and thermal equipment, a mathematical model of the value of the wall hardness of the semi-hot extrusion machine as a key process in the manufacturing technology of steel cylindrical hollow parts manufactured for the mechanical engineering and mining industries was obtained using experimental planning methods. It is noted that the technological process of manufacturing steel cylindrical hollow parts with a key operation of double-sided semi-hot extrusion with distribution is a promising process that allows to ensure high plasticity and strength of the semi-finished product material and obtain the required mechanical properties of the metal. The developed mathematical model made it possible to solve the actual problem of choosing the optimal modes and parameters of the semi-hot extrusion process (processing temperature, degree of deformation, temperature of the cooling medium, geometry of the working tool) and to provide the ability to control the formed properties of the product together with the finishing operations of drawing. Graphical dependences of the wall hardness of the semifinished product on the processing temperature at different values of the radius of the working part of the punch, the degree of deformation and the temperature of the cooling medium are constructed and analyzed. Analysis of the obtained graphs allowed us to identify the parameters that have the greatest impact on the wall hardness of the semi-finished product.

Material Selection and Manufacturing of Halogen Based Headlamp for Two-Wheeler Vehicle Technologies

In the plastic industry, distinctive handling hardware like expulsion, infusion trim, Calendaring, and thermoforming are utilized to fabricate various products. This equipment is fundamentally the improvement of Standard Injection Molding in which Injection Molding is significant. This procedure is utilized for the assembling of the hollow section part and the part with thin wall thickness. This research aimed to develop a halogen-based Headlamp for a two-wheeler vehicle. The essential objective of an automotive headlight is to enhance safety and protection in low light and poor climate conditions. It is the first time that a halogen-based headlamp for a two-wheeler vehicle has been created for the first time in Pakistan. The product in our project consists of three major components, reflector, halogen bulb, and lens. Material selection and processing were the two major tasks in this project. The product was manufactured through injection molding, a high vacuum metallization process, and then finally assembling of parts. To determine the quality of the product, six tests were performed according to Japanese standard JIS-D5500.

Design and technological capabilities of a CNC skew rolling mill

Results of a study investigating a skew rolling process for elongated axisymmetric parts are presented. Despite the fact that the skew rolling technique for producing such parts was developed and implemented in the mid-twentieth century, there are no studies on this problem. The first part of this paper presents the results of FEM modelling of skew rolling stepped axles and shafts (solid and hollow). The FEM analysis was performed using the MSC Simufact Forming software. The numerical simulation involved the determination of metal flow patterns, the analysis of thermal parameters of the material during rolling, and the prediction of cracking by the Cockcroft-Latham ductile fracture criterion. Force parameters of rolling solid and hollow parts were also determined. The aim of the FEM analysis was to determine initial design assumptions and parameters for the development of the skew rolling mill. Later on in the paper, a design solution of a CNC skew rolling mill for rolling parts based on their envelope profile is proposed. FEM strength test results of a mill stand, obtained with MSC. NASTRAN, are presented. Finally, the performance test results of the constructed rolling mill are presented. The experiments involved rolling real stepped shafts that were modelled numerically. Obtained results show that the proposed skew rolling method has considerable potential. The designed and constructed rolling mill can be used to perform the rolling process according to the proposed method, with the tool and material kinematics being controlled based on the set parameters of a workpiece envelope.

Flexural behaviour of hollow concrete beams under three points loading: Experimental and numerical study

This study examines the flexural behaviour of hollow reinforced concrete (RC) beams experimentally, numerically, and analytically. The experimental work was accompanied to study the influence of internal concrete hollow core size on the flexural response of RC beams. A control beam with a solid section and three other specimens having a hollow core area of 3%, 7%, and 10% of the beam cross-section area were tested. During loading, the crack patterns for all the specimens were recorded. The results indicated that using less than 10% of the beam cross-section as the hollow part didn’t considerably affect the failure load of the RC beams. In conclusion, the concrete core didn’t contribute to the capacity of the RC beams; however, it affected the cracking pattern, i.e. size and height. A numerical model was implemented using ABAQUS to simulate the behaviour of the hollow RC beams. The numerical model accurately expected the response of the tested RC beams. Using the validated model, a parametric study was complemented to study the influence of the hollow size and location on the RC beam response.

Improvement of ceramic core strength by combining 3D printing technology and an organic-inorganic conversion process using dual polymers

Ceramic cores are essential for manufacturing hollow mechanical parts, such as impellers and blades, in the casting process. High temperature heat treatment, which causes dimensional deformation and breakage, is required to reveal the effective strength of ceramic cores. Therefore, in this study, a new 3D printing-based process, combined with an organic-inorganic binder conversion process, is proposed to fabricate a ceramic core with high dimensional stability using dual polymers with different chemical properties. The ceramic core was prepared using an extrusion-type 3D printer with a slurry prepared by mixing a starting powder with hydrophilic and hydrophobic polymers. The extruded samples molded from the heterogeneous polymers were immersed in water at 60 °C for 3 min to remove the hydrophilic polymer to create space for impregnating an inorganic binder. The core samples were then dipped in an inorganic binder solution composed of tetraethyl orthosilicate and sodium methoxide and then dried at 80 °C for 1h, followed by a heat treatment at 1000 °C for 1h. Using dual polymers, the amount of inorganic binder coating converted into the glass phase during heat treatment was increased, which resulted in improved core strength. These results confirm that the dual polymer can be used to manufacture ceramic cores with excellent dimensional stability and firing strength through 3D printing combined with the organic-inorganic binder conversion process.

A methodology to obtain traceability for internal and external measurements of Inconel 718 components by means of XRCT

There is undoubtedly an increasing trend towards the use of XRCT as a dimensional metrology tool, driven mainly by the proliferation of complex and hollow parts in the industry. While this technology is suitable for qualitative analysis, a consistent methodology is nevertheless needed, so that XRCT could be considered an accurate and reliable technology for carrying out dimensional and geometrical quantitative analysis.Therefore, the main aim of this approach is to develop a methodology for a traceable measurement of external and internal features.To do it, each measurement is associated with its corresponding task-specific uncertainty estimation by an adapted substitution approach, and thus providing a novel traceable XRCT measurement methodology. The proposed methodology is based on using a reference object related to the workpiece to measure external and internal features of an Inconel 718 component by means of XRCT. In both cases, traceability is guaranteed by the use of conventional dimensional metrology instruments. Results show that wall thicknesses can be accurately measured with errors below 2% for all the cases studied (wall thicknesses from 0.957 to 2.648 mm). As internal measurements are more prone to suffer artifacts, inner diameter deviations from nominal values are from 0.3% in the best XRCT conditions to 19.5% in the worst conditions.With the aim of providing a better scientific understanding of the measurement by means of XRCT, further tests were carried out. CT parameters influence on the beam hardening effect and on the surface definition was studied. Results show that the traceability is assured when the proposed methodology is used.

Quenchability improvement and control simplification by ice mandrel in hot stamping of ultra-high strength steel hollow parts

Abstract To produce ultra-high strength steel hollow parts for reducing the body weight and improving the collision safety of automobiles, a hot stamping process of quenchable steel tubes using ice mandrel and resistance heating was developed. To solve the problem of buckling and low cooling rate during stamping of hollow products, an ice mandrel was inserted in the tube. The effect of the ice mandrel on heating and forming behavior was investigated. Quenchable ice-filled steel tubes were able to heat over austenitizing temperature by adding papers as thermal insulation. Moreover, the ice mandrel simplifies the controlling process by generating a reaction force to prevent the buckling and increase the hardness after die quenching of the ice-filled tubes. Using the ice mandrel with insulating papers is significantly effective to produce ultra-high strength hollow products.

Analytical Solution of Aluminum Alloy Plates With Holes Subjected to Cold Expansion With Reverse Yielding

Abstract The expansion induced by cold working is a common process that generates residual stresses. It is used when fatigue damage accumulation and life reduction of aluminum alloy perforated plates is an issue in the aeronautics industry. This process is an attractive solution to extend the fatigue lifetime of these structures. It aims at generating residual stresses and increases thereby the strength of hollow parts including aluminum alloy plates with holes commonly used in the manufacture of airplane fuselage. Unfortunately, the life predictions require a good prediction of the residual stresses and in particular when reverse yielding takes place. An analytical model to predict the residual stresses induced during the expansion process due to the cold strain hardening is developed. The proposed analytical model is based on an elasto-plastic behavior, with a power law material behavior and relies on the theory of autofrettaged thick wall cylinders in plane strain state to which reverse yielding is incorporated. The application of Hencky theory of plastic deformation is used in the analytical calculations of the stresses and strains. Finite element numerical simulation is used to validate the developed analytical model by comparison of the radial, hoop, longitudinal, and equivalent stresses for both the loading and unloading phases. The obtained results show clearly that the level of residual stresses depend mainly on the interference and strain hardening while reverse yielding reduces the stresses near the hole.

The Chosen Aspects of Skew Rolling of Hollow Stepped Shafts.

The paper presents chosen aspects of the skew rolling process of hollow stepped products with the use of a skew rolling mill designed and manufactured at the Lublin University of Technology. This machine is characterized by the numerical control of spacing between the working rolls and the sequence of the gripper axial movement, which allows for the individual programming of the obtained shapes of parts such as stepped axles and shafts. The length of these zones and the values of possibly realizable cross-section reduction and obtained outlines are the subject of this research paper. The chosen results regarding the influence of the technological parameters used on the course of the process are shown in the present study. Numerical modelling using the finite element method in Simufact Forming, as well as the results of experimental tests performed in a skew rolling mill, were applied in the conducted research. The work takes into account the influence of cross-section reduction of the hollow parts and the feed rate per rotation on the metal flow mechanisms in the skew rolling process. The presented results concern the obtained dimensional deviations and changes in the wall thickness determining the proper choice of technological parameters for hollow parts formed by the skew rolling method. Knowledge about the cause of the occurrence of these limitations is very important for the development of this technology and the choice of the process parameters.

The Effect of the Holding Time on the Formation of Niobium-Vanadium Carbide Coating Onto Aisi 420 by Thermo Reactive Diffusion Process

The deep drawing process had been widely used in automobile, aerospace, electronics, and allied industries to produce hollow parts. The quality of the deep drawing is determined by the dies properties especially their wear-resistant and hardness. Austenitic stainless steel AISI 420 is one of the material of choice for making these dies. In order to increase the wear resistance of the dies, surface treatment such as thermo-reactive diffusion (TRD) technique can be applied owing to their simplicity, low cost, and environment friendly process. TRD technique able to deposit hard layers of carbide, nitride, or carbonitride In this research, TRD techniques will be employed to AISI 420 with special attention given to the effect of holding time during TRD process to form niobium-vanadium carbide (NbVC) coating. The TRD process is carried out by the powder-pack method in a sealed steel container containing powder mixture of niobium and vanadium as master alloy, alumina (Al2O3) as an inert filler and ammonium chloride (NH4Cl) as an activator. The samples were covered with powder mixture and then heated in the electric resistance furnace for 2, 4, and 6 hours at 1000˚C. The crosssection analysis of the NbVC coating observed under microscopy shows that coating thickness increased with longer holding time with 6.95 µm measured in 6 hours holding time. The high hardness of 1333.2 HV also found in the longest holding time of 6 hours. This high hardness is expected to contribute in the wear resistance characterisitic of AISI 420 dies.

Research on magnetorheological elastomer forming process for complicated superalloy hollow part

In this paper, a magnetorheological elastomer (MRE) forming process is developed to form a complicated hollow part of GH4169 superalloy. The novel forming process can realize the differential loading of the forming pressure and avoid liquid leaking in the conventional hydraulic forming process. The principle of the MRE forming process can be illustrated as that the MRE will bulge under the effect of the applied magnetic field. Hence, the local forming pressure in the deformation zone of the part will increase during the forming process. To estimate the range of current and the axial displacement of the punch, a power equation based on power approach and electromagnetic theory is established. Numerical simulations and experiments study the deformation process and the die filling of tube blank under different magnetic field intensities. Response surface methodology (RSM) is used to determine the optimal process parameters. RSM also models the predicted equations of the maximum thinning ratio and the average bulging diameter. Besides, the fitted RSM model’s accuracy is quantified by a statistical method of analysis of variance. Finally, the predicted equations’ reliability and the optimal process parameters obtained by RSM are proved by a validated experiment.

Impulse bit and ablation characteristics of double cylindrical pulsed plasma thruster

Previous studies have shown that the performance of coaxial pulsed plasma thrusters depends on the ratio of propellant surface area-to-cavity volume. In this work, a double cylindrical propellant was introduced to increase the operation ratio compared to coaxial propellants; the results demonstrated that the geometric parameter obtained by dividing the ratio by the hollow diameter greatly influences the impulse bit. Also, direct observations and mass shot measurements revealed a higher density of the ablation gas from the cylindrical part than from the hollow part.