Single Point Incremental Forming Research Articles

Analysis of continuous magnetic field-assisted double-sided incremental forming

This paper describes the analysis of continuous magnetic field-assisted double-sided incremental forming (M-DSIF), a derivation of magnetic field-assisted single-point incremental forming (M-SPIF). In M-DSIF, the driving magnet remains in contact with the workpiece and does not allow for relaxation between individual steps (called contours). M-DSIF enables forming of truncated cones much faster and more accurately than M-SPIF. The number of revolutions per contour of the tool greatly impacts the resulting shape. The proposed two-step M-DSIF is a viable option for distributing material from the center toward the corners of the cone base, which minimizes localized strain in the corners.

Optimisation of Flexible Forming Processes Using Multilayer Perceptron Artificial Neural Networks and Genetic Algorithms: A Generalised Approach for Advanced High-Strength Steels

Flexibility is crucial in forming processes as it allows the production of different product shapes without changing equipment or tooling. Single-point incremental forming (SPIF) provides this flexibility, but often results in excessive sheet metal thinning. To solve this problem, a pre-forming phase can be introduced to ensure a more uniform thickness distribution. This study represents advances in this field by developing a generalised approach that uses a multilayer perceptron artificial neural network (MLP ANN) to predict thinning results from the input parameters and employs a genetic algorithm (GA) to optimise these parameters. This study specifically addresses advanced high-strength steels (AHSSs) and provides insights into their formability and the optimisation of the forming process. The results demonstrate the effectiveness of the proposed method in minimising sheet metal thinning and represent a significant advance in flexible forming technologies applicable to a wide range of materials and industrial applications.

Numerical and experimental study of three-layered Al 1050/Mg AZ31B/ Al 1050 sheets formability considering strain and stress conditions through single point incremental forming

This article examines the formability of 3-layer Al 1050/Mg-AZ31B /Al 1050 sheets experimentally and numerically. Mg AZ31B, with its high strength-to-weight ratio, and Al 1050, with its formability and lightweight, are attractive industrial metals. In the experimental method, the forming limit diagram (FLD), the Forming limit angle (FLA), and the fracture depth were investigated for the 3-layer and base samples with two pyramid and cone geometries. The results showed that the ductility in the cone geometry is higher than that of the pyramid. Also, by comparing the FLD of the 3-layer sample to the base sample, the results showed that the formability of the 3-layer sample increased compared to the Mg-AZ31B base sample. In contrast, the formability decreased compared to the base sample of Al 1050. Numerical studies for predicting the FLD using the SPIF method were carried out using Abaqus software. The numerical techniques considered the second deviation minor strain (SDMIS), second deviation effect strain (SDEF), second deviation thickness (SDT), and second deviation major strain (SDMS). The results showed that the highest accuracy occurred for the SDT method compared to other numerical methods. To remove the effect of the strain path on the numerical analysis for predicting the FLD (from the stress analysis method), a second deviation of von Mises stress (SDVMS) was used. By examining the results, it was found that the results of numerical methods considering stress could be highly accurate.

Effects of ultrasonic vibration on the residual stresses generated during single-point incremental forming

Effects of ultrasonic vibration on the residual stresses generated during single-point incremental forming

Application of artificial neural network in predicting the performance of SPIF for aerospace grade AA7075-T6

Single Point Incremental Forming (SPIF) is recently been used to prepare customized parts with complex geometries. The vertical CNC-milling machine and CNC code are generally used to carry out the forming operation. The material used in the present study is aerospace grade AA7075-T6 due to its inherent properties of high strength-to-weight ratio. The input parameters such as annealing temperature, step depth, tool shape, and the number of cut-out blanks were taken into consideration. The Output parameters like surface roughness and formability were recorded and evaluated by developing an Artificial Neural Network (ANN) based prediction model. Both single-output and double-output neural networks were established for this purpose. In case of one-output structure, the training function of trainlm, transfer function of logsig and 8 no. of neurons whereas, the training function of trainlm, transfer function of tansig and 6 no. of neurons are found to be suitable combination for surface roughness and formability respectively. On the other hand, in case of two-output structure, the training function of trainlm, transfer function of tansig and 10 no. of neurons are found to be suitable. The MAPE and R-values of the developed ANN model denote good agreement with the experimental results. The developed model will reduce the cost, effort, and time of young engineers and practitioners to select accurate parameters without performing expensive experimental runs.

Single-point incremental formability of Monel 400: Coupled grey relational and principal component analyses

This study reports the effects of single-point incremental forming (SPIF) process variables like vertical step down (0.2, 0.4, 0.6 mm), tool diameter (6, 8, 10 mm), feed rate (300, 600, 900 mm/min), spindle speed (300, 450, 600 rpm), lubricant (dry, oil, grease) and sheet thickness (0.6, 0.8, 1.0 mm) on the formability of Monel 400. Based on the varying wall angle tests conducted, it was found that the vertical step down was the parameter most influential in achieving maximum wall angle. The forming limit diagram constructed with the data obtained from straight groove tests revealed the parameter combination for low, moderate, and high formability while forming along different directions (0°, 45°, 90°). Also, it was observed that the formability has been positively influenced by increased tool diameter in the case of 0° orientation, spindle speed in the case of 45° orientation, and vertical step down in the case of 90° orientation. Based on the fractography study, it is concluded that more number of voids enhanced the forming limit. This may be due to the coalescence of voids and their slow aggregation. Based on the combined grey relational analysis and principal component analysis, it is obtained that the order of influencing parameters is vertical step down, tool diameter, sheet thickness, spindle speed, lubricant, and feed rate for obtaining the maximum sum of strains (0°, 45° 90°) and maximum wall angle.

Activation mechanisms of slip systems during hot single point incremental forming of AA2024 sheet

Activation mechanisms of slip systems during hot single point incremental forming of AA2024 sheet

Effect of process variables on microhardness and surface roughness in SPIF of beryllium copper

Beryllium copper is gaining the popularity among material research community owing to its excellent properties like high strength-to-weight ratio, corrosion resistance, and high electrical conductivity. This work aims to enhance the performance of ‘Single Point Incremental Forming (SPIF)’ of Beryllium copper using desirability function analysis (DFA). Feed rate (FEED), Step size (SS), wall angle (WA), and tool rotation speed (TRPM) are the four vital input parameters that have been chosen. This research investigates the effects of variations in these four factors on the truncated cone’s surface roughness and microhardness. After testing different levels of these parameters, the optimal setting using desirability function analysis was 0.4 mm step size, 200 mm min−1 feed rate, 47° wall angle, and a tool rotation speed of 1500 rpm with desirability of 70.7%. Further, measured data was subjected to Analysis of Variance (ANOVA) tests to determine the significance of all parameters on the responses. Results of the ANOVA analysis showed that the step size and tool rotation speed had the most profound impact on surface roughness and micro-hardness respectively. Feed rate and wall angle were the least significant parameters in affecting the surface roughness and micro-hardness respectively. The confirmation experiments validated fine-tuning with predicted and experimental values.

Numerical modelling and experimental investigation of incremental sheet metal forming of Aluminum Alloy Al 3003-O

Abstract Incremental sheet forming (ISF) is an unconventional sheet metal forming technique that can be widely used in the automotive, medical, and aerospace industries. The final product is achieved by moving a rotating tool along a defined spiral or profile tool path controlled by a CNC milling machine. A truncated cone shape was modeled in single point incremental forming (SPIF) to investigate the influence of step size, and sheet initial thickness parameters on the forming force components Fx , Fy , Fz during the forming process.

Investigating intermediate shapes for multi-stage forming of cranial implants

Single Point Incremental Forming (SPIF), a numerically controlled sheet forming technique, excels in adaptability and cost reduction for small-scale production and customized parts. This study explores multi-stage SPIF, focusing on applications in the medical domain, particularly the fabrication of personalized medical implants. Addressing critical challenges related to formability and accuracy, this study emphasizes the significance of multi-stage forming and the importance of the design of intermediate shapes. Forming a cranial implant using one intermediate stage is studied, preliminary in pure Zinc as a cost-effective alternative for heated Ti. The intermediate shape is generated using automatic geometry adaptations such as translating and scaling the CAD model. Nine different experiments are conducted and compared in terms of final geometric accuracy and thickness distributions. The study shows that the proposed intermediate shapes for multi-stage forming significantly improve the geometric accuracy from 1.08 mm mean absolute deviation in traditional single stage forming to 0.41–0.59 mm. However, the used intermediate shapes have a strong but varying effect on thickness distributions throughout the part, showing the importance and sensitivity of the exact intermediate geometry. These insights provide a valuable understanding of the process, shaping the pathway for enhanced utilization of SPIF and setting the stage for future improvements.

Ultrasonic vibration-assisted single point incremental forming of hemispherical shaped component using AA3003 material

ABSTRACT Ultrasonic vibration-assisted single point incremental forming is a recent hybrid process variant of the single point incremental forming process. In this process, longitudinal ultrasonic vibration is used as an assistance in the conventional forming process. In this paper, the effect of amplitude of vibration in the ultrasonic vibration assisted single point incremental forming process have been researched. For the same, experimental work has been carried out by forming the hemispherical shaped components using multistage forming strategy. Moreover, numerical simulation work has been carried out using the LSDYNA solver and the results have been discussed in the light of depth of forming and strain distribution. The experimental fracture forming line is also developed for the AA3003 material for single point incremental forming process. High amplitude of vibration of 12 micron with 20 kHz frequency leads to poor formability; however, the lower amplitude of vibration of 8 micron with 30 kHz frequency leads to good formability.

Manufacture of tunnel-shaped sheet metal parts with improved accuracy using novel toolpath strategies for single point incremental forming

Manufacture of tunnel-shaped sheet metal parts with improved accuracy using novel toolpath strategies for single point incremental forming

Thermo-Mechanical Numerical Simulation of Friction Stir Rotation-Assisted Single Point Incremental Forming of Commercially Pure Titanium Sheets.

Single point incremental forming (SPIF) is becoming more and more widely used in the metal industry due to its high production flexibility and the possibility of obtaining larger material deformations than during conventional sheet metal forming processes. This paper presents the results of the numerical modeling of friction stir rotation-assisted SPIF of commercially pure 0.4 mm-thick titanium sheets. The aim of this research was to build a reliable finite element-based thermo-mechanical model of the warm forming process of titanium sheets. Finite element-based simulations were conducted in Abaqus/Explicit software (version 2019). The formability of sheet metal when forming conical cones with a slope angle of 45° was analyzed. The numerical model assumes complex thermal interactions between the forming tool, the sheet metal and the surroundings. The heat generation capability was used to heat generation caused by frictional sliding. Mesh sensitivity analysis showed that a 1 mm mesh provides the best agreement with the experimental results of total forming force (prediction error 3%). It was observed that the higher the size of finite elements (2 mm and 4 mm), the greater the fluctuation of the total forming force. The maximum temperature recorded in the contact zone using the FLIR T400 infrared camera was 157 °C, while the FE-based model predicted this value with an error of 1.3%. The thinning detected by measuring the drawpiece with the ARGUS non-contact strain measuring system and predicted by the FEM model showed a uniform thickness in the drawpiece wall zone. The FE-based model overestimated the minimum and maximum wall thicknesses by 3.7 and 5.9%, respectively.

Analysing the mechanisms of failure in polycarbonate sheets deformed by SPIF

This article presents experimental research conducted on polycarbonate sheets deformed via single-point incremental forming (SPIF). Building upon established frameworks from previous studies, the analysis focuses on evaluating the formability and failure modes, particularly necking and fracture, of polymeric sheets in both conventional and incremental forming processes. The experimental design encompasses an investigation of spindle speed and step down process parameters, utilizing both oil and water as lubricants, to comprehensively assess their effects. The findings provide insights into how these parameters influence formability and affect the failure mode. When using oil as a lubricant, three distinct failure modes were observed during deformation: fracture, twisting, and crazing. An increased twisting was associated with higher step down values, whereas elevated spindle speeds contributed to increase crazing. Additionally, these tests revealed a “post-crazing” failure mode following deformation. Conversely, when water was used as a lubricant, only fracture and twisting were observed in the SPIF specimens. This work introduces, for the first time ever, a complete investigation of these failure modes through scanning electron microscopy analysis of the failure surface. This analysis scrutinizes surface features and interprets them, thus providing a valuable tool for failure analysis.

Innovative tool designs to improve formability in case of single point incremental forming

Single point incremental forming (SPIF) is one of the dieless sheet metal forming processes that offer flexibility in the customized fabrication of required parts. Improvement in formability in the case of SPIF has been one of the burning issues in the metal-forming fraternity in the past decades. In the present study, different tool tip geometries, namely hemispherical, elliptical, en-grooved, and triangular tool tips, were employed in the SPIF of 0.8 mm thick CRCA (cold rolled close annealed) steel, and the influence on the forming height was assessed in reference to the commonly used hemispherical tool tip. It was observed that tool geometry has a significant influence on forming height obtained with SPIF, and a maximum of 27% increase in forming height was observed with the en-grooved tool tip with a considerable reduction in the forming force required.

Innovative high degree of freedom single-multipoint incremental forming system for manufacturing curved thin-walled components

This study proposed a new design and control framework for a novel high degree of freedom single-multipoint incremental forming (HDoF-SMIF) system to manufacture curved thin-walled components. First, a novel HDoF-SMIF system was designed based on the principles of HDoF-SMIF technology (including the description of the mechanical structure and network topology). Following that, to realize the process control of the HDoF-SMIF process, this study introduced a novel control strategy for the tool deflection angle specific to robotic incremental forming. It also developed a synergistic motion control approach for the lifting platform and an accelerated computation method to determine the forming parameters for a multipoint reconfigurable die. Then, a novel HDoF-SMIF principle prototype and control program were built for the designed HDoF-SMIF system structure and control method. Finally, the feasibility of the HDoF-SMIF system was verified with the forming test on the domed component, and the geometrical accuracy and wall thickness distribution of the samples were measured using a 3D optical scanner system to evaluate the forming quality of the established HDoF-SMIF system. The results showed that compared to the conventional single-point incremental forming (SPIF) process, the developed HDoF-SMIF system can provide a more uniform thickness distribution of the formed part with a lower overall thickness thinning rate. Furthermore, by increasing the tool deflection angle with a 1 mm elastomeric interpolator, the overall part's forming accuracy and surface quality can be effectively improved.

Influence of ultrasonic vibration on forming force of 1060 aluminum sheet single point incremental forming

A device combining ultrasonic vibration plastic processing technology and single point incremental forming was developed in this work, with maximum power output of 2 kW at frequency of 20 kHz. On this basis, together with theoretical study, experiments and finite element simulation on forming force with aluminum alloy sheet 1060, the results showed that the forming force reduced evidently by appropriate selection of amplitude and frequency, meanwhile, the change of them had a remarkable influence on plastic behavior which can be summarized into two opposite aspects: the softening and the hardening effect. When a lower amplitude and frequency was applied to the forming process, the softening effect dominated, leading to a decrease of forming force, however, under the application of a high-vibrating amplitude and frequency, the harden effect dominated resulting in the decline of plasticity and the increase of flow resistance. The theoretical analytical results and the finite element simulation results are in good agreement with the experimental results, which verified the accuracy of the theoretical model and simulation model. The research results provide theoretical and technical basis for selecting vibration parameters of ultrasonic vibration single point incremental forming.

Optimizing the SPIF parameters for enhancing microhardness and surface quality in Inconel 625 superalloy components

Inconel 625, a high-strength superalloy with excellent corrosion resistance, discovers wide applications in critical sectors such as aerospace, nuclear, marine, and petrochemical. Single-Point Incremental Forming (SPIF) has appeared as an adequate fabricating process for shaping superalloy components. This work used a systematic approach, implementing Response Surface Methodology (RSM) to explore the influence of SPIF process variables, including tool nose diameter, step size, tool spindle speed, and wall angle, on microhardness (MH) and surface roughness (SR). The experimental results have been analyzed to determine the influencing process variables and their optimal settings, which simultaneously enhance MH and reduce SR of Inconel 625 superalloy truncated cones using analysis of variance and the desirability function analysis approach. The most significant parameters that influence MH and SR were TND and SS, respectively. The development of quadratic models for MH and SR has been completed successfully. The maximum MH of 486.8 HV and minimum SR of 0.432 µm have been obtained at the optimal parametric setting of TND = 15 mm, SS = 0.4 mm, TSS = 900 rpm, and WA = 57.5° with the desirability values for MH, SR and combined are 0.832, 0.933, 0.881 respectively. The F-value of the MH model = 109.18 and SR Model = 78.24 implies that both models are significant and both models have excellent prediction strength. The percentage error between predicted and actual values of MH and SR in confirmation run results is less than 5 %.

Fabrication of a prototype of bumper beam by single point incremental forming of laser welded tailored blank and characterization of its quasi-static crushing performance

Fabrication of a prototype of bumper beam by single point incremental forming of laser welded tailored blank and characterization of its quasi-static crushing performance

Feasibility Study of Single-Point Incremental Forming for Discontinuous-Fiber CFRP Using Oil-Bath Heating

Although, three-dimensional printing has several advantages, however there are currently many limitations. In particular, printed products using composite materials such as fiber-reinforced plastic have yet to achieve the same mechanical properties as those obtained from conventional manufacturing methods. In addition, fabricating thin plates or thin shell shapes with sufficient strength is challenging. Incremental forming enables high-mix, low-volume production of thin sheets. This method applies incremental deformation to thin sheets, the desired shape is obtained by accumulating the deformation, and no dies are required. Carbon-fiber-reinforced plastic (CFRP) materials have high specific strength. Discontinuous-fiber CFRP is capable of large plastic deformation under appropriate conditions due to the discontinuity of the reinforcement, and its mechanical properties are nearly isotropic due to the random fiber arrangement. The authors focused on this property and studied the application of single-point incremental forming to discontinuous carbon-fiber-reinforced polyamides. In this study, the workpiece was formed by heating it locally to a deformable temperature by the frictional heat between the rotating tool and the workpiece. The forming experiment was also conducted in an oil bath to keep the entire material at a suitable forming temperature. The results showed that the spindle speed affected forming results even in an oil bath and that heating using an oil bath suppressed deviations from the sine law for thickness and wall angle due to elastic deformation.