Papers by Keyword: Process Window

Abstract: This work reports enhanced high-voltage blocking capability and an enlarged process window for junction termination extension (JTE) in SiC power devices using a hybrid random and channeling implantation for p-type doping (Al), compared with conventional random-only implantation. A three-step hybrid implantation process has been developed to replace a nine-step random implantation, achieving a similar doping profile and equivalent breakdown voltage in the JTE while significantly increasing fabrication productivity and reducing cost. Moreover, TCAD studies reveal that when using the same number of steps and ion energies as the conventional random implantation method, the JTE realized by the channeling-incorporated hybrid approach enables an increased breakdown voltage and a widened dose window in SiC devices. This is attributed to a deeper Al distribution with a lower average concentration, which effectively alleviates electric field crowding.

Abstract: Abstract. Tubes with non-uniform thickness are needed to even out wall thickness in draw bending and provide higher stiffness in specific directions in some applications. Tailored local heating of the tubes in tube sinking operations should reduce the local flow stresses and facilitate differential deformation along the circumference of tubes to form tubes with uneven wall thicknesses. Local heating of tubes prior to entry into the die in tube sinking is implemented in this research to form tubes with higher thickness in desired directions. Initial experiments are conducted using plasma heating by tungsten inert gas (TIG) welding equipment on EN AW 6060 AlMgSi0.5 aluminum tubes. The process window is described by varying the process temperature (weld current between 50 A and 80 A) while altering the degree of deformation, the tube diameter, and tube thickness. Tubes with no defects were formed at 50 A. Increasing the weld current led to a higher wall thickness (up to 25% thickness increase), however, high weld currents also favored the formation of surface defects, wrinkle formation, or burn-through holes depending on the process setup. The process window was larger for tubes with higher wall thickness.

Abstract: Semisolid processing can provide an avenue to reduced rejection rates during casting and increased capability of thin-walled castings leading to improved resource efficiency and reduced climate impact. In the RheoMetal^TM process, the slurry is formed far from equilibrium. A consequence to the deviation from equilibrium is that conventional guidelines for process stability may not give the correct appreciation of the process window, nor on the correct solid fractions generated. The solid fraction provides the slurry properties and its dependence on temperature should in theory provide the stable process window. This is discussed using data from literature and an alternative approach to identify the process stability window is given.

Abstract: Tailored Tool Tempering (TTT) is an innovative method able to calibrate the strength and ductility characteristics of the components manufacture by means of Press-Hardening process. The process parameters that most influence the final mechanical properties of the soft zone are quenching time and temperature of the heated tools.In this work, with the aim of defining a process window to estimate the soft zone properties of an automotive B-pillar in Usibor^®2000 steel using TTT Press-Hardening approach, the strength and ductility of the soft zone are studied varying the quenching time and the temperature of the heated tools. Using a numerical-experimental approach, a Finite Element (FE) model is firstly developed in AutoForm to simulate the TTT Press-Hardening process and to define thermo-mechanical cycles that are characteristics of the soft zone as a function of quenching parameters (quenching time and temperature of the heated tools). FE thermo-mechanical cycles are then physically simulated on Usibor^®2000 specimens using Gleeble 3180 system. The treated specimens are subsequently subjected to micro-hardness and tensile tests. Experimental results are adopted to train an artificial neural network used to construct the process window.

Abstract: For Automated Tape Placement process, degree of bond varies with variation in process parameters and material. Interlaminar bond strength characterization is one of the most important criteria in determining the quality of bond between two layers of thermoplastic tapes. Depending on the bond strength achieved using different process parameters, a process window is defined. Based on the process window an iterative procedure is adopted to find optimum parameters to realize maximum bond strength. This paper aims to investigate the interlaminar bond strength of thermoplastic CF-PA6, during Automated Tape Placement process. A fairly new heating source, a pulsed light solution, i.e. a humm3^TM system, which delivers uniform, highly controllable heat to the nip point is used. Experiments were conducted for different process parameters and results obtained using wedge peel test were analyzed. Results acquired help in assessing the material and the heating source in terms of capabilities and efficiency.

Abstract: This research aims at analyzing and optimizing the hydroforming process parameters to achieve a sound bulged tube without failure. Theoretical constitutive model is formulated to build up a working diagram including process window, which is used to optimise the process parameters and predict the formability and the failure of the tube accurately. The model is validated using the published experimental and analytical results of previous research works for 37% bulging ration of low carbon steel (C1010). The model gave a very good agreement with the published data.

Abstract: Precipitation-hardenable 6xxx series aluminum alloys are incorporated in many structural components with due consideration of their good combination of properties including a relatively high strength, outstanding extrudability and excellent corrosion resistance. Accordingly, AA6061 has been identified as a very good candidate material for structural lightweighting of transportation vehicles. However, the weldability of aluminum alloy (AA) 6061 by means of conventional technologies such as GMAW and GTAW methods is limited by sensitivity to solidification cracking. In this respect, friction stir welding (FSW) presents a tremendous potential for assembly of aluminum structures for the transportation industry due to the low heat involved that can mitigate crack formation and, thus, translate into improved mechanical performance of the assembly. In this work, FSW of 3.18 mm thick AA6061-T6 sheets in the lap joint configuration was investigated. This configuration is considered to be more challenging for assembly by FSW than the butt joint type due to the orientation of the interface with respect to the welding tools and the necessity to break the oxide layer on two aluminium alloy planar surfaces. Weld trials were performed to examine the influence of the FSW tool geometry and process parameters on the welding defects, microstructure, hardness and bend performance. Unacceptable material expulsion and/or significant thinning in one of the two overlapped sheets were produced under most conditions. A set of FSW tool geometries leading to a viable process operational window under which the risk of defects could be mitigated and/or eliminated was identified in this study.

Abstract: Pulsed phase thermography (PPT) is a common infrared technique for quantitative nondestructive testing and evaluation (NDT&E). PPT was initially applied in the aeronautical and aerospace engineering to the detection and quantification of defects in materials with either high or low thermal conductivity, such as aluminium and composite materials. This paper presents for the first time the application of PPT-technique for defect inspection in sheet metal parts, attempting to provide a solution for an alternative quality control rather than the traditional optical survey in the press shop. The inspected defects in this paper were produced in deep drawing cups, to effectively creating various crack lengths and depths respectively in both steel and aluminium alloys. The approach of the characterizing influence parameters is primarily based on the particular parameters of the PPT-technique. These parameters were firstly classified into various categories, and a DoE model was subsequently designed to define the required experiments for a process window analysis. According to the defined process window, more accurate conclusions of defect detecting effects were achieved. Studies in the paper present the fundamental perceptions for defect inspecting in the sheet metal parts by using PPT-technique in the press shop.

Abstract: Aluminum alloys have great potential for lightweight construction. In order to achieve an optimized properties distribution for the forming operation and to enhance the formability of aluminum alloys, so called Tailored Heat Treated Blanks (THTB) are developed. In this context, this paper is about the local precipitation hardening of sheet metals for the application of THTB. By using a specific, short-term heat treatment via conductive heating plates the thermal induced hardening of the fast hardenable alloy AA6181PX is quantified and qualified. Considering the processibility of the local precipitation hardening for THTB, a process window for the heat treatment parameters is presented allowing a precise setting of the mechanical material properties.

Abstract: The nanoindentation test and geometry measurement have been conducted to evaluate the hardness and geometry changes of bonded Au ball bonds towards the changes of the selected wire bonding parameters namely bonding power, bonding time and bonding force. Three indentations were made on the bonded ball bonds to evaluate the variation of hardness properties with the location of indentation. It was noted that the increase of bonding or ultrasonic power will increase the hardness value for the indentations 1 and 3 located at the periphery of bonded ball bonds. The increase of bonding power also increased the deformation of bonded ball bonds. It was also shown that the increment of bonding time will increase the hardness value across the bonded ball bonds in almost even distribution. The application of the bonding force in the wire bonding process has the least effect on the hardness and geometry changes on the bonded ball bonds.