Cold Wire Drawing Research Articles

Changes in Microstructure, Mechanical and Electrical Properties with Progress of Cold Wire-Drawing for AA1070

Commercial AA1070 alloy for electrical wire is severely deformed by the drawing process when a rod with a diameter of 2 mm is greatly reduced to 0.4 mm by multi-pass. Changes in the microstructure, mechanical properties, and electrical properties of the Al alloy during the wire-drawing process were investigated in detail. The as-drawn Al wires showed a deformation structure in which the grains are greatly elongated in the drawing direction, even though recovery and/or partial recrystallization occurred more actively in the specimens which had more than 84% in reduction of cross-sectional area (<i>R<sub>A</sub></i>). In addition, the fraction of high angle grain boundaries tended to increase with the increase of <i>R<sub>A</sub></i>. For all drawn specimens, the fiber texture of the {110}<111> and {112}<111> components was mainly developed, and their maximum intensity tended to increase with increasing <i>R<sub>A</sub></i>. Recrystallization texture of (001)[100] and (110)[001] began to appear at an <i>R<sub>A</sub></i> higher than 84%. The hardness tended to increase with increasing <i>R<sub>A</sub></i> due to work hardening. In particular, increasing <i>R<sub>A</sub></i> to 84% resulted in a great rise in hardness, accompanied by a distinct non-uniformity in hardness in the thickness direction. However, the average hardness hardly changed at <i>R<sub>A</sub></i> above 84%, even when <i>R<sub>A</sub></i> was increased to 96%. The strength also tended to increase stepwise as <i>R<sub>A</sub></i> increased, very similar to the change in hardness. The specimen with an <i>R<sub>A</sub></i> of 93% showed the highest tensile strength of 192 MPa, 2.8 times higher than that of the specimen before drawing. The electric conductivity did not decrease significantly, even with extreme increases in <i>R<sub>A</sub></i>, and remained at an average value of 61.6 %IACS.

Development of thermal-resistant Al–Zr based conductor alloys via microalloying with Sc and manipulating thermomechanical processing

Thermal-resistant Al–Zr based conductor alloys were developed using microalloying with a low level of Sc (≤0.10 wt%) and two thermomechanical processing routes, in which the cold wire drawing was conducted before and after the aging treatment. The mechanical properties, electrical conductivities, and thermal-resistant properties of several alloys were investigated and evaluated according to the IEC standard of thermal-resistant aluminium conductors. The evolutions of the precipitates and grain structure during processing were also studied. The microalloying with Sc resulted in the precipitation of a large number of fine Al3(Sc,Zr) precipitates, which provided substantially high strength of 188–209 MPa, representing 73–88% improvement compared to the Sc-free base alloy, while maintaining excellent electrical conductivity of 57.4–59.9% IACS. Moreover, the Sc-containing alloys exhibited outstanding thermal-resistant properties, where the maximum strength reduction was limited to ≤6.0% after thermal exposures at 310 and 400 °C. The best combinations of mechanical properties and electrical conductivities of the Sc-containing alloys were obtained after aging at 350 °C for 48 h, following solutionizing at 600 °C for 8 h. Both processing routes yielded comparable precipitation strengthening and strain hardening, and consequently comparable mechanical and electrical properties, where the maximum differences in the strength and electrical conductivity between both routes were 12 MPa and 1.4% IACS, respectively. The excellent combinations of mechanical, electrical, and thermal-resistant properties made the developed alloys promising candidate materials for four standard grades of thermal-resistant aluminium conductors, while taking advantage of an affordable material cost and using conventional thermomechanical processes.

SUPERIOR COATING TECHNOLOGY FOR ADVANCED COLD WIRE DRAWING OF SPRING STEELS

The technology of cold wire drawing belongs to an ancient class of technologies, but their use lasts for centuries. Today, special forming machines, advanced tool materials and effective lubricants are used. In this paper, a progressive physical vapour technology (PVD) of coating for inner surfaces is used which resulted in significant prolongation of tool life. The technology of HiPIMS (High-power Impulse Magnetron Sputtering) exhibited excellent performance in protective (Al,Ti)N coating of whole inner surfaces that are in contact with the drawn wire which is impossible to do with other coating techniques. The increase in production of the drawn steel spring wire by the coated die by more than 100% was excellent, and it opens new horizons to some similar technological applications.

Multi-pass cold rolling and wire drawing process of gadolinium and its magnetocaloric effect

Owing to low ductility of magnetocaloric material (MCM)s, the plastic deformation process is quite challenging, and information available on the deformation process of MCMs is limited. In this study, the cold rolling and wire drawing processes of Gd wire including heat treatment were conducted. Uniaxial compression test of as-cast and heat treated Gd rod was conducted to evaluate the material property. The magnetocaloric effect (MCE) of drawn Gd wire was indirectly measured using a vibrating sample magnetometer (VSM). Pass schedule of cold rolling and wire drawing process for the Gd wire of Ø1.0 was designed. Finite element (FE) simulation of drawing process was conducted to investigate the drawing force for each drawing pass and strain distribution. Friction coefficient between the drawing die and Gd wire was evaluated via FE simulation and drawing experiments using a lubricant. Magnetic properties of the deformed and annealed Gd wire were evaluated and compared. The evaluated magnetic properties have shown that the presented process schedule is reasonable for manufacturing magnetocaloric wire without diminishing the magnetocaloric effect.

JOB SAFETY ANALYSIS ON MANUFACTURING PROCESS OF HOUSE WIRES

The objective of this project is to analysis of hazards in the process of house wire manufacturing in VGuard industries limited Coimbatore for the purpose of improving safety in the workplace and promoting safety culture among the workers. Manufacturing process involves cold wire drawing process, copper cable bunching process, Insulation process, testing and material handling process all of this process having its own significant hazards. By using the Job safety analysis technique, the analysis was carriedout and the study is submitted as a report to V-Guard industries limited Coimbatore. Here the proposed practical solution in the sequence of Elimination, Substitution, Engineering control, Administrative control, and Personal Protective Equipment using the observation form Job Safety Analysis worksheet

Process Stability and Reproducibility of the Dieless Drawing Process for AZ31 Magnesium Wires

Magnesium (Mg)-based wires are in the focus of interest for numerous applications like micro-forming technologies or medical engineering. Manufacturing thin Mg-based wires is widely realized by applying a conventional multiple pass cold wire drawing process. This requires a complex manufacturing schedule of multiple passes with intermediate heat treatments to overcome work hardening, because of the cold forming process. Especially Mg and its alloys are known for their rather low formability at room temperature associated with the hexagonal close-packed lattice structure. The dieless drawing process uses local heating to initialize a localized plastic zone under an external tensile load to achieve higher reductions in diameter in a single wire drawing pass. It can therefore present a solution for a more efficient warm manufacturing process of Mg-based wires. In this study, the stability of the steady state material flow during a dieless wire drawing process and its reproducibility was investigated. For this purpose, a variation of process parameters was selected and wire manufacturing was carried out using magnesium alloy AZ31. A single and double dieless drawing process was applied. Additionally, a conventional cold wire drawing process including a die with the same forming schedule was executed as a benchmark experiment. The results of this study show, that the dieless drawing process is not only a stable process after reaching the steady state, but it is also a reproducible and accurately adjustable process. Moreover, the dieless drawing process maintains the property profile of the starting material to a large extend.

Copper Wire Multi-Pass Drawing: Process Modeling and Optimization

During cold wire drawing process, the drawing stress applied to the wire at the exit of the die must be lower than the material yield stress (including strain-hardening) to avoid wire necking and fracture. Several studies have been developed to investigate and model the stress acting on the wire in the single pass drawing and its dependence on the main process parameters. The aim of this work is to apply an analytical model for the calculation of the drawing stresses during the whole complex multi-pass manufacturing process in industrial environment, considering not only the forces acting in the die but also the driving forces of the rotating capstans (drawing tension and back tension). The drawing of ETP Pure Copper (99.9% in weight), using two industrial multi-pass machines with different reduction ratio sequences, is analysed and then discussed in order to understand the different failure rates. Finally, the study compared step by step, the evolution of the drawing stresses respect to material yield stress when different processing conditions (i.e. change of capstan windings, change of friction conditions in the die and in the capstan) are applied.

Study of mechanism of austenite formation in surface during cold drawing of wire made of austenitic-martensitic steel VNS9-SH

The study of the microstructure, microhardness distribution and phase composition of 0,36 and 0,95 mm diameter wire made of austenitic-martensitic trip steel VNC9-Sh after cold drawing was carried out. According to the results of the research, a mechanism for the formation of austenite in the surface was proposed. The mechanism of formation of structural components was indirectly confirmed by the method of computer modeling of the cold drawing process with the calculation of the distribution of temperature fields.

The influences of the variable speed and internal die geometry on the performance of two commercial soluble oils in the drawing process of pure copper fine wire

The cold wiredrawing process constitutes a classical-tribological system in which a stationary tribe-element (die) is in contact with a tribe-element in relative motion (wire) and both interacting with the interfacial tribe-element (lubricant). This condition is reflected in the effect of friction as a function of the drawing speed and temperature, and directly affects the wearing of the surface into the die and the final quality on the drawn wire. The aim of this work has been to determine the best conditions to process ETP-copper using two different types of oil/water emulsion lubricants. For this purpose, six different die geometries have been proposed and a set of tests have been carried out at different speeds (between 1 and 21 m/s) to determine those combinations that give a lower value in the required drawing force (Fd). The experiments allowed to know the friction coefficient (µ), the temperature profile inside the drawing die and in the lubricant and also the mean roughness (Ra) in the drawn product. The results have shown that drawing speeds above 10 m/s significantly decrease the drawing force and, as a consequence, the friction effect on the interface. The best results have been achieved in the combinations of the lower die angle (2β = 14°) with drawing speeds between 17 and 18 m/s with both types of lubricants used, obtaining the lower values of the friction coefficient between µ = 0.10–0.15 with the lubricant type D (Agip S234-60 oil at 7% concentration). It has been found that those tests carried out with dies with a smaller approach angle have generally made it possible to obtain better qualities in the final product. Additionally, FEM simulations have been done to analyse those cases with the lower values of µ, throwing values of Fd that are consistent with those measured in the experimental setting and allowing to better understand the behavior of the material as it passes through the die.

Induction Annealing of Austenitic Spring Steels for Nuclear Reactors

Abstract This paper describes designing and experimental trials of an induction annealing method for AISI 321H austenitic steel wires. Specifically, it explores the feasibility of incorporating an existing frequency controller into a wire drawing line to provide induction heating of the wire stock to annealing temperatures. In-process annealing is necessary to make cold wire drawing possible by restoring the ductility of the wire stock. The reason is that the wire products are required to have strengths in excess of 1600 MPa in some cases. Hence, the only way to meet this requirement is to apply severe deformation combined with sufficiently effective polygonization.

Improving strength of cold-drawn wire by martensitic transformation in a 0.65 wt% C low-alloy steel

Ultrahigh strength can be obtained by cold drawing of high-carbon steel wire, but the strength heavily relies on the extent of cold-drawn deformation and it is difficult to produce ultrahigh strength steel wire with large diameter. In this study, a new method by combination of cold-drawing and martensitic transformation was reported to significantly improve the strength of cold-drawn steel wire. By using the new method, the strength of the steel wire can be increased to over 2.4 GPa, which is much higher than its corresponding original cold-drawn wire (less than 2.0 GPa), while sacrificing only a small ductility. By using electrochemical etching, transmission electron microscopy and X-ray diffraction, the prior austenite grain size and the microstructure of the martensitic steel wires was analysed. After the heat treatment, the large cold deformed steel wire with 8 pass drawing displays grains of 4.9 μm and dislocation-substructured martensite; while the small cold deformed wire with 6 pass drawing results in coarser grains and a mixture substructure of dislocation and twin in martensite. The results demonstrate that the extent of cold-drawn deformation has a great influence on grain refinement in the later heat treatment; grain refinement to less than 5 μm will lead to martensite substructure transition from twin to dislocation, and thus endows the martensitic steel wire moderate ductility. In addition, calculation indicates that precipitate hardening and dislocation strengthening contribute about 76.9% to the yield strength, and martensite lath boundary strengthening contributes about 18% to the yield strength.

Drawing of magnesium fine wire and medical application of drawn wire

Magnesium is not only classified as one of the lightweight materials, but also expected to be applied in medical stents and medical artificial joint screws because of its good biocompatibility and biodegradability in the human body. Our research has studied the production of sound pure magnesium fine wire for the medical stent by the cold drawing method. Pure magnesium wires are known to have low ductility and poor formability at room temperature. It is pointed out that its crystal structure has a close-packed hexagonal crystal and hence the slip surface during deformation is limited. Therefore, the cold drawing of magnesium wire is very difficult. In this research, the finite element analysis (FEA) and Cockroft-Latham fracture criterion have been conducted to clarify the optimum drawing conditions for obtaining a fine wire without an internal crack by studying the relation between the die half angle and the pass reduction that affects the drawability of pure magnesium wire. The results show that 6o of die half angle and 13 % of pass reduction are suitable conditions to prevent an internal crack. Furthermore, the intermediate annealing process was also examined to prevent the generation of small voids in the center of the wire. Consequently, we succeeded to draw the fine wires with 0.5 mm in diameter without internal cracks and good finishing surface roughness.

An inverse analysis to identify the Johnson-Cook constitutive model parameters for cold wire drawing process

Johnson-Cook constitutive equation was utilized to model the 10100 copper and AA 1100 aluminum wires at the cold wire drawing process. Initial Johnson cook parameters were determined through quasi-static tensile tests at different strain rates. Analytical and finite element with VUHARD subroutine solutions were implemented to calculate the drawing forces using the Johnson cook parameters. Wire drawing experiments were carried out at different drawing conditions with two areal reductions and four drawing speeds with the strain rate ranged from 37 s−1 to 115 s−1 and wire drawing forces were measured using a load cell connected to the drawing die. Results showed that the Johnson cook model with parameters determined from a quasi-static condition was not able to predict the material behavior at the wire drawing process with a moderate strain rate. In order to modify the initial JC parameters an inverse analysis approach was adopted. An objective function was defined based on analytical and experimental drawing forces differences with respect to JC parameters. Using the Newton–Raphson method, new JC parameters were identified by minimizing the objective function. Updated Johnson cook parameters showed much more correlation with experimental results.

FE Analysis of Cold Wiredrawing for High Precision Extra Fine Wire

FE Analysis of Cold Wiredrawing for High Precision Extra Fine Wire

FE Analysis of Cold Wiredrawing for Extra Fine Wire

FE Analysis of Cold Wiredrawing for Extra Fine Wire

Numerical investigation of wire-clamp contact for a drawing machine

Machines for cold wire drawing are widely spread in the industrial field to reduce wires’ section. The system is complex, because the axial pulling force has to correctly deform wires into the drawing dies. The present work focuses on a continuous press and pulling system, with a track-chain. Normal force at the steel clamps can be generated independently on the axial force, but avoiding slipping and local yielding at the external surface of the wire. The work presents a numerical model of wire-clamp contact, focusing on the yielded area at the wire surface, and aimed at the identification of the limit clamping force that avoids slipping and yielding. Reliability of results is critically discussed, based on the choice of element formulation and type, and mesh refinement. Based on this analysis, control parameters of the drawing machine are modified to experimentally verify this limit normal force estimated by the numerical model.

Study on the Deformation Homogeneity and Electrical Conductivity in Co-Cr-Ni-Mo Wires Drawn with Different Drawing Practices

This study investigates the influence of cold wire drawing practices namely full die drawing (FDD) and half die drawing (HDD) on the deformation homogeneity in Co-35Ni-20Cr-10Mo alloy (MP35N) wires which are used for manufacturing implantable medical products. The inhomogeneous factor was used to assess the level of inhomogeneity in the wires, and electrical conductivity was measured on the wires, after drawn to different cold work (CW) reductions and with different drawing practices. Electron beam scattered diffraction, field emission scanning electron microscope and transmission electron microscope characterization were performed on the wire samples to correlate the mechanical and electrical properties to their texture and grain size. The results of this study conclude that the wires drawn with the FDD practice exhibited homogenous deformation, uniform microstructural and hardness gradient across the wire when compared to HDD wires. The electrical conductivity of the HDD-drawn wires was higher than the FDD wires and the level of inhomogeneity and the variation of conductivity decreased with the increase in CW.

Experimental investigation of industrial copper deformed by wire drawing process

The scope of this work is to investigate the effect of the cold deformation by wire-drawing on microstructure and physical properties of industrial copper wires. Copper wires were provided by E.N.I.CA.Biskra (Algeria). We investigated some wires with different strain levels (as received, 1.20, 2.10, and e = 3.35). X-ray diffraction, optical microscopy, and electrical resistivity measurement have been used as characterization techniques. We analyzed the photographs using “ImageJ” software and DRX patterns using PM2K software. The results revealed that the cold wire-drawing causes a lengthening of grains along the axis of wire-drawing, and introduced large amounts of defects. The results also showed, on the one hand, the decrease in crystallite size, lattice parameter, and the outer cut-off radius, on the other hand, the increase of the electrical resistivity and the dislocation density in the copper wires. Keywords : Industrial copper; deformation; Dislocations; Shape factor; X-ray diffraction.

Effects of chemical composition on drawability and mechanical properties of magnesium alloy wires

In recent years, in the manufacturing sector, magnesium is becoming very highly used material for the manufacturing of wires for various purposes, but due to its low strength a vast variety of magnesium alloys are being implemented instead. This research focuses on the effect of chemical components of alloying elements in magnesium alloys wires, considering the workability for cold wire drawing of the materials and their mechanical properties and comparing them to similarly drawn magnesium wires.

Influence of drawing practices on the mechanical, texture and work hardening characteristics of Co-Cr-Ni-Mo wires

This study investigates the influence of cold wire drawing practices namely Full Die Drawing (FDD) and Half Die Drawing (HDD) on the microstructure, mechanical and work hardening characteristics on Co-35Ni-20Cr-10Mo material. The wires were subjected to different reductions using a multipass drawing approach and the resulting microstructures were characterized by EBSD and FESEM. It was found that wires drawn with FDD practice showed a higher Yield strength (σYS,) Ultimate Tensile strength (σUTS), higher work hardening rate, and different regimes of work hardening curves when compared to the wires drawn with HDD practice, for the same amount of Cold Work (CW). It was observed that FDD wires had a smaller grain size, homogenous texture and higher amount twins and dislocations in the microstructure, whereas the HDD wires exhibited coarser grains, non-uniform texture and a lower amount of lattice defects.