Primary Process Parameters Research Articles

Impact of friction diffusion welding parameters on the properties of rare earth containing magnesium alloy tube-tube plate welds

Hybrid Friction diffusion welding experiments were carried out as per three factors, five levels, central composite rotatable design matrix to investigate the influence of primary process parameters namely, rotational speed, dwell time and tool projection on the joint strength of tube to tube plate magnesium alloy welds. Response surface methodology was used to establish an empirical relationship between the joint strength and the most influencing parameters. It was observed that, the parameters such as rotational speed and dwell time had the greater influence on the peak temperature and strain rate, which in turn affected the quality of bonding at the tube to tube weld interface. Whereas, the annular volume of bonded region was strongly affected by tool projection. Use of optimum values of rotational speed, dwell time and projection yielded proper metallurgically bonded weld interface free from micro defects such as interface cracking, wedge cracking and matrix cracking. Fracture surface examination indicated that, the joint strength was influenced by bonding quality of weld nugget and ductility was influenced by the nature of bonding at tube to tube weld interface.

Prediction of surface roughness ratio of polishing blade of abrasive cloth wheel and optimization of processing parameters

Abrasive cloth wheel is significantly flexible at high-speed rotation and could realize adaptive micro-surface contact polishing of the blade of aviation engines. To reduce surface roughness and improve the surface integrity and mechanical property of the blade of aviation engine, this study determined the primary and secondary processing parameters by using orthogonal test and range method. Results show a significant linear correlation between blade surface roughness before and after polishing. A range of polishing parameters for orthogonal central combination test was determined based on the tendency chart. A roughness ratio prediction model was established based on the orthogonal central combination test results. This model was verified significant by variance and diversity analyses. The polishing parameters were optimized using response surface method. Finally, polishing experiment using a blisk confirmed the reliability of the established prediction model and the optimized parameters.

Study on the Hot Processing Parameters-Impact Toughness Correlation of Ti-6Al-4V Alloy

In this research, the hot processing parameters-impact toughness correlation of Ti-6Al-4V titanium alloy is studied. Fifty-four groups of hot processing treatments with different forging temperatures (930, 950, 970 °C), deformation degrees (20, 50, 80%), annealing temperatures (600, 700, 800 °C), and annealing time (1 and 5 h) were conducted. The orthogonal design was used to find the primary hot processing parameters influencing the impact toughness of Ti-6Al-4V alloy. The results show that the annealing temperature can exert the biggest influence on impact toughness. Low annealing temperature is essential to achieve high impact toughness value. In addition, the BP neural network was used to describe the quantitative correlation between hot processing parameters and impact toughness. The results show that the BP neural network exhibits good performance in predicting the impact toughness of Ti-6Al-4V alloy. The prediction error is within 5%. The BP neural network and the orthogonal design method are mutually confirmed in the present work. Finally, based on the microstructure analysis, the reasons responsible for above experimental results are explained.

Optical droplet vaporization of nanoparticle-loaded stimuli-responsive microbubbles

A capillary co-flow focusing process is developed to generate stimuli-responsive microbubbles (SRMs) that comprise perfluorocarbon (PFC) suspension of silver nanoparticles (SNPs) in a lipid shell. Upon continuous laser irradiation at around their surface plasmon resonance band, the SNPs effectively absorb electromagnetic energy, induce heat accumulation in SRMs, trigger PFC vaporization, and eventually lead to thermal expansion and fragmentation of the SRMs. This optical droplet vaporization (ODV) process is further simulated by a theoretical model that combines heat generation of SNPs, phase change of PFC, and thermal expansion of SRMs. The model is validated by benchtop experiments, where the ODV process is monitored by microscopic imaging. The effects of primary process parameters on behaviors of ODV are predicted by the theoretical model, indicating the technical feasibility for process control and optimization in future drug delivery applications.

Cold flow defects in zinc die casting: prevention criteria using simulation and experimental investigations

High-pressure die casting of zinc alloys is increasingly used in the manufacturing of parts with high aesthetic value. These parts must comply with strict requirements on surface quality, which are generally overlooked in traditional mechanical applications. Cold flow defects, which are a primary concern for surface quality, originate from several different causes that have not yet been fully understood. This report investigates the factors that influence cold flow defects and the choices that can lead to an improvement in surface quality. The research method is based on a case study performed at a die casting company. First, an existing process has been analyzed using simulation to explain the causes of cold flow defects observed in production samples. The temperature at the end of the cavity fill has emerged as a key index for the occurrence of defects, which can be controlled by three primary process parameters: injection velocity, temperature of the cooling medium, and lubricant spraying time. These same factors are then assessed using experimental tests on an existing die, where the number of defects in the selected regions of the casting has been evaluated by image processing. The results suggest that the surface quality can be particularly improved by increasing the flow rate of the molten metal through the gates and avoiding excessive flow turbulence in the wide cavity sections. Consequently, the increase in the gate area has been identified as a specific criterion for the die design. These findings have been validated in the redesign of the die and the selection of the process parameters, which have resulted in a significant reduction in the surface defects.

Developing Empirical Relationships to Predict Tensile Properties of Friction Welded AISI 52100 Grade Steel Rods <sup></sup>

In this work, friction welding of AISI 52100 grade steel rods of 12 mm diameter was investigated to predict the value of tensile strength. The Joints made with various process parameter combinations were subjected to tensile tests. The primary process parameters are considered in ratios (friction pressure/friction time, forging pressure/forging time, rotational speed/sec). This is done to make as three factors. Here, the three factors, five levels, central composite, rotatable design matrix are worn to optimize the required number of experiments. The Empirical relationships were developed by Response Surface Method (RSM). The adequacy of the models was checked through ANOVA technique. Through using the developed Empirical relationship, Ultimate Tensile Strength (UTS) of the joints can be predicted by means of 95% confidence level.

Multi-wire submerged arc welding: a study of secondary process parameters

The goal of this thesis is to investigate the effect of secondary process parameters on the geometry of the weld bead in multi-wire submerged arc welding. Bead-on-plate welding experiments will be conducted using 3, 4 and 5 wires. The parameters being varied will be the wire stick out, the angles of the torches and the spacing in between. Primary process parameters like voltage, current and welding speed will be kept constant. Penetration, bead width and height, percentage dilution, HAZ, weld penetration shape factor and weld reinforcement shape factor will be measured and evaluated. Fewer experiments will be needed because of the use of a design of experiments approach, namely a fractional factorial design. This will allow to determine the significance of each single parameter and their mutual interaction with respect to weld bead shape.

A new class of bioactive glasses: Calcium–magnesium sulfophosphates

Low-melting ionic sulfophosphate glasses from the system P2O5-SO4-MO-Na2O (M = Zn(2+), Ca(2+) or Mg(2+)) have been previously shown by us to allow tuneable aqueous dissolution and also enable processing temperatures well below 400°C. Sulfate ions are extremely safe for use in the body as decades of use of calcium sulfate bone grafts testifies and there is no known limit on their adult oral toxicity. This glass system therefore offers great potential for use as biomaterials, especially in organic-inorganic hybrid systems such as glass-polymer composites for tissue engineering or drug encapsulation and delivery applications. A compositional region was identified where stable sulfophosphates of the type P2O5-SO4-(Ca, Mg, Zn)O-Na2O can be fabricated. For these glasses, the viscosity-temperature-dependence, glass transformation temperatures (Tg ) and the onset of crystallization were evaluated as the primary processing parameters. As a first step in exploring their potential as a biomaterial, in this study we examine the bioactivity of several compositions of these glasses using fibroblast, monocyte, and osteoclast cell culture models to determine cellular responses in terms of attachment, proliferation, differentiation, and toxicity.

“Vitamin E” fortified parenteral lipid emulsions: Plackett–Burman screening of primary process and composition parameters

The objective of this study was to screen the effect of eight formulations and process parameters on the physical attributes and stability of “Vitamin E”-rich parenteral lipid emulsions. Screening was performed using a 12-run, 8-factor, 2-level Plackett–Burman design. This design was employed to construct polynomial equations that identified the magnitude and direction of the linear effect of homogenization pressure, number of homogenization cycles, primary and secondary emulsifiers, pre-homogenization temperature, oil loading, and ratio of vitamin E to medium-chain triglycerides (MCT) in the oil phase on particle size, polydispersity index, short-term stability, and outlet temperature of manufactured emulsions. The viscosity of vitamin E was reduced from 3700 (100%) to 64 mPa.s (30%) by MCT addition. As viscosity is critical for efficient emulsification, vitamin/MCT ratio was the most significant contributor for the stability of emulsions. Particle size increased from 236 to 388 nm, and percentage vitamin remaining emulsified after 48 h dropped from 100 to 73% with increase in vitamin/MCT ratio from 30/70 to 70/30. Significant decrease in particle size and PI, and an increase in outlet temperature were also observed with increase in homogenization pressure and number of homogenization cycles. Emulsifiers and oil loading, however, had insignificant effect on the responses. Overall, stable submicron emulsions at vitamin/MCT ratio of 30/70 could be prepared at 25,000 psi and 25 cycles in ambient conditions. The identification of these parameters by a well-constructed design demonstrated the utility of screening studies in the “Quality by Design” approach to pharmaceutical product development.

Die-sink EDM in Meso-Micro Machining

Micro EDM has been identified since more than a decade as suitable process for machining complex shaped structures with high aspect ratio, though only through variations of EDM such as micro EDM milling, micro EDM drilling, coated electrodes etc. In the current paper, we present the research focused on analysing the capability for implementation of die-sink EDM in meso - micro scale machining (structures with surface area smaller than 10mm2 down to 0.05mm2) by concentrating on primary process parameters to obtain high material removal rate, low tool electrode wear with high form accuracy and precision. Graphite electrodes were mill machined in meso-micro scale with high precision and accuracy. Low tool wear technology was developed for using graphite electrodes in meso-micro EDM offering economical and energy efficient solution in meso-micro scale machining.

Effects of Manufacturing Process Conditions on Sensory Attributes and Microstructure of Ice Cream

The primary process parameters of the homogenization pressure and freezing process (drawing temperature and overrun) for ice cream manufacture were examined to determine their impact on the sensory attributes and odor sensor response of ice cream. Fifteen process conditions were selected using a Box-Behnken design, while 12 sensory attributes were obtained as assessment items based on sensory evaluations using quantitative descriptive analysis (QDA). Eleven of these sensory attributes changed significantly according to process conditions, suggesting that such conditions can have a major impact on ice cream's sensory attributes, even for a fixed make-up of ingredients. Furthermore, observed correlations between the sensory attributes and microstructural attributes of the ice cream led to the conjecture that the sensory attributes were influenced by changes to the ice cream's structural conditions resulting from the process conditions. A correlation was also observed between the odor sensor response and the overrun condition, but no clear correlations were found to exist within the ice cream structure or the sensory attributes.

Application of Twin Screw Extrusion in the Manufacture of Cocrystals, Part I: Four Case Studies

The application of twin screw extrusion (TSE) as a scalable and green process for the manufacture of cocrystals was investigated. Four model cocrystal forming systems, Caffeine-Oxalic acid, Nicotinamide-trans cinnamic acid, Carbamazepine-Saccharin, and Theophylline-Citric acid, were selected for the study. The parameters of the extrusion process that influenced cocrystal formation were examined. TSE was found to be an effective method to make cocrystals for all four systems studied. It was demonstrated that temperature and extent of mixing in the extruder were the primary process parameters that influenced extent of conversion to the cocrystal in neat TSE experiments. In addition to neat extrusion, liquid-assisted TSE was also demonstrated for the first time as a viable process for making cocrystals. Notably, the use of catalytic amount of benign solvents led to a lowering of processing temperatures required to form the cocrystal in the extruder. TSE should be considered as an efficient, scalable, and environmentally friendly process for the manufacture of cocrystals with little to no solvent requirements.

Study on Injecting Forming Technology of Railway Locomotive Bearing Retainer

According to the superiority performance, the applications of engineering plastics tend to be widely used day by day in the field of railway transport. The research of locomotive-bearing retainer is an important technology that should be resolved proposed by the Ministry of Railways’ report on the outline of the Eleventh Five-Year Plan. In this paper, the characteristics of each process of the injection molding in the different stage, the main technology parameters, and the influence of the primary process parameters on the part manufacture quality were systematically analyzed. And the modern injecting forming software and new technology were applied to analyze the injecting forming technology, to design the mould structure, to forecast the possible defects and breakdown in the process of injecting forming with the thematically design and the CAE technology. The study results can be extended to the design of other similar parts, which has very strong engineering applications significance.

On Parameter Selection in Cold Spraying

For cold spraying, a method for the construction of the window of deposition and the selection of optimum process parameters is presented. Initially, particle impact velocity and the critical particle velocity for bonding are worked out and expressed explicitly in terms of key process and material parameters. Subsequently, the influence of particle velocity on coating characteristics is examined in view of the results of experiments and simulations. It has been found that main coating characteristics can be described as a unique function of the ratio of particle velocity to critical velocity, here referred to as η. Finally, coating properties are linked directly to primary process parameters via parameter selection maps, where contours of constant η are plotted on a plane of gas temperature versus gas pressure. Inferences of the presented method and the resulting parameter selection maps are discussed for the example of copper as feedstock material.

Fluorination deposition on carbon nanofibers by PTFE decomposition as a facile method to enhance dispersion and interaction in PVDF composites

A facile method for surface modification of nanofillers was developed in order to improve interfacial interaction and dispersion within poly (vinylidene fluoride) (PVDF) matrix. Rather than using the more conventional toxic fluorine gas method of treating nanofillers, a new method of depositing a fluorination coating from decomposition of polytetrafluoroethylene (PTFE) on a carbon nanofiber (CNF) surface was developed. The primary process parameters such as CNF/PTFE ratios and processing temperatures were studied through FTIR and morphological analysis. The fluorination coated CNFs (f-CNFs) were prepared successfully under the conditions of the CNF/PTFE ratio of 1 : 5 at 460 °C. The morphological evidence showed that the enhanced dispersion of the f-CNFs and interfacial bonding with PVDF matrix were efficiently induced by the easily manipulated surface modification method. The coating effect for the CNFs was also clearly demonstrated from the electrical conductivity results by comparison of the nanocomposites with f-CNFs and as-received CNFs. Dynamic mechanical analysis results indicated that due to the surface coating on the CNFs, the contribution of the f-CNFs to the storage modulus was dramatically increased from ∼120 MPa to 1000 MPa at −90 °C, an increase by a factor of about 8 times. This study confirmed that the new surface coating method provides a simpler way for practical modification of nanofillers, i.e. through decompositions of polymers, for treatment of nanofillers.

The study on defects in aluminum 2219-T6 thick butt friction stir welds with the application of multiple non-destructive testing methods

The present study focused on the relationship between primary friction stir welding process parameters and varied types of weld-defect discovered in aluminum 2219-T6 friction stir butt-welds of thick plates, meanwhile, the weld-defect forming mechanisms were investigated. Besides a series of optical metallographic examinations for friction stir butt welds, multiple non-destructive testing methods including X-ray detection, ultrasonic C-scan testing, ultrasonic phased array inspection and fluorescent penetrating fluid inspection were successfully used aiming to examine the shapes and existence locations of different weld-defects. In addition, precipitated Al2Cu phase coarsening particles were found around a ‘kissing-bond’ defect within the weld stirred nugget zone by means of scanning electron microscope and energy dispersive X-ray analysis. On the basis of volume conservation law in material plastic deformation, a simple empirical criterion for estimating the existence of inner material-loss defects was proposed. Defect-free butt joints were obtained after process optimization of friction stir welding for aluminum 2219-T6 plates in 17–20mm thickness. Process experiments proved that besides of tool rotation speed and travel speed, more other appropriate process parameter variables played important roles at the formation of high-quality friction stir welds, such as tool-shoulder target depth, spindle tilt angle, and fixture clamping conditions on the work-pieces. Furthermore, the nonlinear correlation between weld tensile strengths and weld crack-like root-flaws of different lengths was briefly investigated.

Variable cavity volume tooling for high-performance resin infusion moulding

This article describes the research carried out by Warwick under the BAE Systems/EPSRC programme ‘Flapless Aerial Vehicles Integrated Interdisciplinary Research - FLAVIIR’. Warwick's aim in FLAVIIR was to develop low-cost innovative tooling technologies to enable the affordable manufacture of complex composite aerospace structures and to help realize the aim of the Grand Challenge of maintenance-free, low-cost unmanned aerial vehicle manufacture. This article focuses on the evaluation of a novel tooling process (variable cavity tooling) to enable the complete infusion of resin throughout non-crimp fabric within a mould cavity under low (0.1 MPa) injection pressure. The contribution of the primary processing parameters to the mechanical properties of a carbon composite component (bulk-head lug section), and the interactions between parameters, was determined. The initial mould gap ( di) was identified as having the most significant effect on all measured mechanical properties, but complex interactions between di, n (number of fabric layers), and vc (mould closure rate) were observed. The process capability was low due to the manual processing, but was improved through process optimization, and delivered properties comparable to high-pressure resin transfer moulding.

C1020/Al6063 이종 합금의 맞대기 마찰교반접합의 접합특성

The Friction Stir Welding (FSW) has mainly been used for making butt joints in Al alloys. Development of FSW would expand the number of applications. The FSW is a relatively solid-state joining process. This study possibility of a welding between C1020 and Al6063 by means of FSW has fundamentally clarified. The primary process parameters, such as a rotating speed, rotating direction of tool and off-set of pin periphery from materials interface were optimize, respectively.

Development of a tungsten plasma etch process for IR nanobolometer fabrication

In this paper we present our development of a SF 6/Cl 2-based plasma etch recipe for a LAM Research 4720 etch chamber. Our tungsten plasma etch recipe is used to pattern nanoscale resistor features integrated within a novel IR sensor process. We characterised the nanoscale etch in terms of five primary process parameters using a 16-run V fractional factorial experiment, to provide accurate estimates of all main effects and two-factor interactions. The experimental results determined the target levels for the etch process parameters. Our optimised nanoscale tungsten etch module was then integrated within a CMOS/MEMs-compatible nanobolometer infrared (IR) sensor fabrication flow. Our use of tungsten improves the reliability of the sensor pixels at elevated stress current levels, when compared with equivalent Ti-based pixel structures, and demonstrates the potential of tungsten as a CMOS-compatible nanobolometer material.

Study on fabrication process parameter estimation by visual measurement

AbstractThe cross‐sectional dimensions of the photoresist in the photolithography process are estimated from top‐down scanning electron micrographs for improved control of photolithography conditions. As semiconductor design rules shrink, strict process control is becoming increasingly important. Two primary process parameters in the photolithography process, exposure dose and focus position, require strict control in order to achieve the desired photoresist profile. The relationship between the photoresist profile and changes in these two parameters of photolithography is determined by simulation, and features suitable for estimation of the photoresist profile are identified in conventional images obtained for critical dimension monitoring. Experimental results demonstrate that process parameters can be estimated to within error of 1.0 mJ/cm2 for exposure dose and 80 nm for focus position, making the proposed method suitable for photolithography process control. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(8): 11–17, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10153