Short Cycle Time Research Articles

Preparation and characterization of a metal-rich activated carbon from CCA-treated wood for CO2 capture

The disposal of eucalyptus poles used in the electricity network distribution is considered a potential contamination to the environment due to the chromated copper arsenate (CCA) used as a wood preservative. The thermochemical process can be an alternative to this toxic waste disposal. In this work, the slow pyrolysis of CCA-treated wood followed by the production and application of activated carbon was proposed. Metal retention (ICP-OES), concentration of non-condensable gases produced in the pyrolysis process (via GC), as well as the capacity of activated carbon on CO2 adsorption (via TGA) were investigated. The highest formation rate of non-condensable gases was observed at 500°C, while the maximum H2 concentration was at 700°C. The char obtained in the pyrolysis was chemically treated with H3PO4 and activated in CO2 flow. The pore size distribution of activated carbons showed pore sizes lower than 1nm. The activated carbons showed a CO2 adsorption capacity of 70–83mg/g. The presence of chromium and copper may have influenced the CO2 adsorption. The fast adsorption and desorption showed by the activated carbon produced from CCA-treated wood is interesting to systems that operate in short-time cycles, as pressure swing adsorption (PSA). The reuse of CCA-treated wood for activated carbon production and its application in the CO2 adsorption could be a solution to minimize the environmental damage caused by this waste.

In-situ creep law determination for modeling Spark Plasma Sintering of TiAl 48-2-2 powder

Spark Plasma Sintering (SPS) is a process which allows powder densification, applying simultaneously a uniaxial external load and pulsed direct current of very high intensity through tools. This process is attracting significant attention, with a tremendous increase of studies in the metal powder densification field. Its growing popularity lies in the very fast heating rate and short cycle time driven by the Joule effect, which limits grain growth. However, this process implements different coupled electrical, thermal and mechanical phenomena. All this makes the process difficult to develop and to apply for routine industrial production, which has motivated the development of numerical simulation tools in order to understand and optimize the process. Up to now, very few models integrating the coupling between heat generation, electric transfer and mechanics have been proposed.In particular, a numerical predictive model for powder densification requires a good understanding of the mechanical behavior, in our case a viscoplastic compressive law (Abouaf mechanical model). In this article, we will discuss the characterization of the material during densification, focusing on the creep behaviors of dense and porous state materials used to simulate sintering in the Abouaf framework. Validations of the creep law parameters and also of the densification parameters will be presented and subsequently discussed.

Modelling of an innovative liquid rotational moulding process

An innovative liquid rotational moulding process aiming at using standard injection-moulding polymer grades, shortening cycle times and at accessing more higher-end markets is studied. In this new process, the polymer is melted beforehand in a conventional injection unit and injected into the mould rotating around two axes. This work focus on modelling the liquid polymer flow occurring in this process, as well as providing guidance on the choice of process parameters. First, a stability criterion for rimming flow is derived, defining the process and material parameters space available for a functional process. From this criterion, it appears that initial thickness, and density have a destabilising effect, while liquid viscosity and angular velocity have a stabilising effect. Next, using Lax-Friedrichs scheme, the one-dimensional transient gravity driven liquid film is numerically modelled, linking the total extent of spreading to the frequency of orientation reversals and to the major and minor angular velocities ratio : the closer this ratio to one, the larger the extent of spreading. Then, Computational Fluid Dynamics (CFD) simulations are carried out to take into account three-dimensional features in the moulding of a cube part. Finally, comparison with trials performed on the moulding of the same cube part validates entirely this approach. In particular, some peculiar features of spreading can only be explained and reproduced when employing three-dimensional CFD simulations.

Automatic Design Optimization of Profiled Endwalls Including Real Geometrical Effects to Minimize Turbine Secondary Flows

This paper presents a novel optimization methodology based on both adjoint sensitivity analysis and trust-based dynamic response surface modeling to improve the performance of a modern turbine of a large civil aero-engine in the presence of high-fidelity geometry configurations. The system has been applied to the nonaxisymmetric hub and tip endwall optimization of a high-pressure turbine stage making use of multirow 3D simulations, parametric modeling, and rapid meshing of real geometry features such as rim seals and modeling of film cooling flows. It has been shown in previous papers that improvements gained using simplified models of the stage are lost when applying the high-fidelity geometry configuration. New results presented in this paper indicate that controlling the purge flow that exits the disk space through the rim seal at the hub of the main annulus is more significant than the reduction of secondary flows in the main passage. For a given rim sealing mass flow rate and whirl velocity, the nonaxisymmetric endwalls are optimized such that the detrimental impact of the sealing flow on the turbine performance is reduced, and hence, the stage efficiency is significantly increased. The traditional optimization approaches based on evolutionary methods or even sequential modifications for defining the endwalls shape are computationally demanding. Since turbomachinery industry continuously strive to reduce the design cycle time, in particular when high-fidelity 3D computational fluid dynamics (CFD) is used, the main body of this paper outlines the novel methods developed to produce a practical design in a very aggressively short design cycle time.

Application of high resolution melting analysis in the molecular diagnosis of inherited diseases

The basic principle of high resolution melting (HRM) is that DNA-saturated fluorescent dye is added into the PCR reaction system; the PCR amplicon is denatured by heating in a certain temperature range; specialized instrumentsdetect degeneration double-stranded DNA fluorescence signal and draw the melting curve and then wild-type and heterozygous mutants are differentiatedaccording to different melting curve shape. HRM technology is widely used in gene mutation scanning because of its advantages of simplicity, accuracy, fastness, low cost, short cycle time and high throughput.In addition, compared with other mutation screening methods, HRM analysis is a real closed-tube method, which indicates that high-resolution melting analysis is directly performed after PCR reaction and HRM technology is more convenient.In conclusion , HRM technology is a new technology for mutation screening and genotyping.(Chin J Lab Med, 2017, 40: 146-148) Key words: Genetic diseases, inborn; Polymerase chain reaction; Mutation; Genotyping techniques; High resolution melting

A novel concept of agile assembly machine for sets applied in the automotive industry

Flexibility and agility are principles increasingly necessary and used in current automotive manufacturing processes due to the market paradigm change, going from mass production to customized one. Some countries, where the human labour cost is very attractive, design processes depending essentially on the workers’ performance. However, some risks can be induced by the use of intensive labour due to uncertainties related to human behaviour and fatigue. Small assembly operations comprising a large variety of models and short cycle time are usually carried out manually, due to their flexibility and agility. However, critical factors such as quality, commitment with the delivery time, and increase of labour costs become attractive factors to start developing flexible and agile equipment that allows simple set-up, short cycle time, and traceability. Robotics is widely used to cover these purposes, but the required space to operate with a robot and the cost involved (which will need tools as an automatic equipment) make unfeasible its use in some applications.

プラスチック射出成形における可変圧力プロファイルとプロセスパラメータの多目的最適設計

Process parameters in plastic injection molding (PIM) such as packing pressure, melt temperature and cooling time have a direct influence on the product quality and it is important to determine the optimal process parameters for the high product quality as well as the high productivity. This paper proposes a method to determine the optimal process parameters in the PIM for high product quality and high productivity. In particular, the variable packing pressure profile that the packing pressure varies through the packing phase is adopted as the advanced PIM. Warpage and cycle time are taken as the product quality and the productivity, respectively. Therefore, a multi-objective optimization of the process parameters using the variable packing pressure profile is performed. Numerical simulation in the PIM is so intensive that a sequential approximate optimization using radial basis function is adopted. It is found through the numerical result that the proposed packing pressure profile can improve both the warpage and the cycle time. Based on the numerical result, the experiment is also carried out. It is confirmed through the numerical and experimental result that the variable packing pressure profile is an effective approach for the warpage reduction and the short cycle time.

Advanced Welding Technology for Highly Stressable Multi-Material Designs with Fiber-Reinforced Plastics and Metals

Organic sheets made out of fiber-reinforced thermoplastics are able to make a crucial contribution to increase the lightweight potential of a design. They show high specific strength- and stiffness properties, good damping characteristics and recycling capabilities, while being able to show a higher energy absorption capacity than comparable metal constructions. Nowadays, multi-material designs are an established way in the automotive industry to combine the benefits of metal and fiber-reinforced plastics. Currently used technologies for the joining of organic sheets and metals in large-scale production are mechanical joining technologies and adhesive technologies. Both techniques require large overlapping areas that are not required in the design of the part. Additionally, mechanical joining is usually combined with “fiber-destroying” pre-drilling and punching processes. This will disturb the force flux at the joining location by causing unwanted fiber- and inter-fiber failure and inducing critical notch stresses. Therefore, the multi-material design with fiber-reinforced thermoplastics and metals needs optimized joining techniques that don’t interrupt the force flux, so that higher loads can be induced and the full benefit of the FRP material can be used. This article focuses on the characterization of a new joining technology, based on the Cold Metal Transfer (CMT) welding process that allows joining of organic sheets and metals in a load path optimized way, with short cycle times. This is achieved by redirecting the fibers around the joining area by the insertion of a thin metal pin. The path of the fibers will be similar to paths of fibers inside structures found in nature, e.g. a knothole inside of a tree. As a result of the bionic fiber design of the joint, high joining strengths can be achieved. The increase of the joint strength compared to blind riveting was performed and proven with stainless steel and orthotropic reinforced composites in shear-tests based on the DIN EN ISO 14273. Every specimen joined with the new CMT Pin joining technology showed a higher strength than specimens joined with one blind rivet. Specimens joined with two or three pin rows show a higher strength than specimens joined with two blind rivets.

Design and Technology Research of Hot Trimming Die of High Strength Steel for Hot Forming Parts

Hot trimming technology of high-strength steel is to compound trimming process in hot stamping, so that the sheet can be trimmed or punched with high ductility and low hardness, which can improve product quality, shorten cycle time and reduce the production cost. In this research, we researched the influence of trimming temperature, clearance on trimming force, sheared surface quality .The results are as follows: trimming force decrease with the trimming temperature, clearance increase; the higher temperature, smaller clearance assures smoother sheared surface. Based on the above laws, optimal processing parameters are trimming temperature above 700 °C, clearance about 10% of the mould.

Wheel lift-off in creep-feed grinding: thermal damage, power surge, chip thickness and optimisation

An investigation is made into the phenomenon of early lift-off in creep-feed grinding, where the wheel lifts away from the workpiece before reaching the end of cut. In single-pass operations, early lift-off can result in thermal damage. In multi-pass operations, there is a surge in material-removal rate just before lift-off, which can result in thermal damage and excess wheel wear. This study examines the current inadequate methods of dealing with lift-off. It then develops a geometric and kinematic model for analysing the lift-off phenomenon. It finally proposes a thermal-model-based optimisation method for achieving a constant maximum surface temperature, resulting in shorter cycle times and less risk of thermal damage. The power-surge model is validated experimentally in diamond grinding of tungsten-carbide rotary tools.

Creating load-adapted mechanical joints between tubes and sheets by controlling the material flow under plastically unstable tube upsetting

Abstract Mechanical joining processes provide various advantages over conventional fusion welding of metallic components such as shorter cycle times, little or no heat input and reduced need for subsequent surface finishing operations. Several investigations in the past have shown that joints between tubes and sheets or plates can be manufactured by upsetting operations. Under axial compression, the tube develops a plastic instability in form of bulge. In-between two such bulges, a force and form fit to sheet material can be created. Previous work concentrated on forming fully developed bulges, i.e., at the end of the bulging process, both hinges of the bulge are in contact. This paper presents a numerical and experimental study aiming at optimizing the bulge shape to increase the bearable limit loads. Two new bulge designs are investigated, an ‘arrow bulge’ and a ‘wave bulge’. The paper details the results of FE-simulations of the bulge shapes under bending and torsion loads. Forming tools were designed and both bulge shapes were produced experimentally. The results show that the material flow under compressive plastic instability can be controlled and that the resulting bulge shapes yield improved strength in various load cases.

Role of Electronic Customer Relationship Management in Demand Chain Management

In 21st century, collaborative business supply chain environments are required to be proactive rather than reactive so that they can better deal with the uncertainty, growing competition, shorter cycle times, more demanding customers and pressure to cut costs. Demand chain management as a new business model requires investing in consumer insights and closer relationships in the supply chain to conduct predictive analysis of retail intelligent solutions. In this regard new kinds of methodologies are required to be discussed. However, at the execution level the limitations in terms of scalability, data integration and knowledge based decision support to providers or suppliers in terms of strategy building and in providing deductive inference capabilities are to be addressed. Therefore, it is required to describe how predictive analytics helps in constructing the knowledge base to conduct verification and validation in terms of semantic predictive analytic for the domain of demand chain management.

A 0.65--1.35 GHz synthesizable all-digital phase locked loop with quantization noise suppressing time-to-digital converter

This paper presents a new quantization noise suppression method for a time-to-digital converter (TDC) and proposes an all-digital phase-locked loop (ADPLL) architecture using only standard cell logic gates. Using a new multiple input multiple output (MIMO) quantization noise suppression method provides an order of $\sqrt {2N} $ improvement in TDC resolution with $N$ parallel TDC channels. Suppressed noise in the TDC allows the ADPLL to achieve superior jitter performance in both theoretical calculations and simulation results. In order to allow fast portability between process nodes, short design cycle time, ease of modification, and flexibility, ADPLL architecture is designed completely in register transfer level intensive Verilog code and the implementation is synthesized in order to obtain final microelectronic design schematics. In comparison to similar work in the literature, postlayout simulation results show that the designed ADPLL achieves period jitter of 1.78 ps$_{rms}$ with a layout area of 0.09 mm$^{2}$ in 65 nm CMOS process and power consumption of 17.5 mW at 800 MHz.

Incremental dry forging - Interaction of W-DLC Coatings and Surface Structures for Rotary Swaging Tools

Rotary swaging is an incremental cold forging process with very short cycle times for manufacturing of complex bar or tube profiles such as axles or gear shafts made of steel or aluminum alloys. Conventional rotary swaging requires high amounts of lubricants usually made of crude oil. Dry rotary swaging would improve the ecological balance of this process considerably and would also accelerate the process due to cleaning of the manufactured components after processing becomes obsolete.This study deals with a first benchmark of dry rotary swaging as a function of macro and micro-structured tool surfaces coated with wear resistant and low friction a-C:H:W coating systems with respect to the resulting workpiece quality and tribological process conditions. In addition, the influence of a surface finishing is investigated related to the dominating and locally changing coating wear mechanisms. The presented results allow for further coating development towards dry rotary swaging.

Forming and Joining of Carbon-Fiber-Reinforced Thermoplastics and Sheet Metal in One Step

The processing and component properties of metals have led to their worldwide success in mechanical engineering. Their advantages are high ductility, efficient production methods, good joining ability and nearly isotropic mechanical properties. Fiber-reinforced plastics (FRP) are known for an excellent lightweight design potential, due to low density as well as high and anisotropic tensile stiffness. By using thermoplastics instead of thermoset matrices, processing times and therefore component costs have already been reduced significantly and thus have become affordable in large-scale application. If the advantages of both, metal and FRP, are intelligently combined, a part with tailored properties is created. However, suitable forming processes, which take the different forming effects of both materials into account, have to be developed yet.The scope of this research was to enable the combined forming, joining and impregnation of pre-impregnated FRP-sheets and sheet metal to steel-CFRP-steel-sandwich-parts in one process step. As forming and joining must be executed at temperatures above the melting point of the thermoplastic while the part removal must take place beneath this temperature, a heating concept for drawing tools was developed to enable short production cycles. In order to ensure an economic industrial production a fast heating and cooling of the tool is essential. Afterwards optimal impregnation and joining process parameters for short cycle times were determined with planar samplings. The influence of the process parameters on part quality was investigated microscopically. Based on this research, a forming tool was constructed and hat profiles of steel-FRP-steel sandwiches were drawn successfully. Subsequently, the impregnation quality was investigated based on the process parameter tool temperature. Furthermore, the geometrical deviation of formed hat profiles was investigated.

A mathematical model and optimization of total production cost and quality for a deteriorating production process

Proper production planning can considerably improve a producer’s competitiveness in delivering low-cost products with high quality and short-cycle time. In a deterioration process, the quality may ...

Effect of extended famine conditions on aerobic granular sludge stability in the treatment of brewery wastewater

Results obtained from three aerobic granular sludge reactors treating brewery wastewater are presented. Reactors were operated for 60d days in each of the two periods under different cycle duration: (Period I) short 6h cycle, and (Period II) long 12h cycle. Organic loading rates (OLR) varying from 0.7kgCODm−3d−1 to 4.1kgCODm−3d−1 were tested. During Period I, granules successfully developed in all reactors, however, results revealed that the feast and famine periods were not balanced and the granular structure deteriorated and became irregular. During Period II at decreased 12h cycle time, granules were observed to develop again with superior structural stability compared to the short 6h cycle time, suggesting that a longer starvation phase enhanced production of proteinaceous EPS. Overall, the extended famine conditions encouraged granule stability, likely because long starvation period favours bacteria capable of storage of energy compounds.

Implementing New Age Performance Management System in IT MNC: Leveraging Communication and Training

Performance management system has been used since decades to measure and manage employee performance. Over the years, changing business scenario, shorter cycle times, changing workforce demographics, ever-increasing demand on performance has pushed organizations to come up with innovative ways to measure and manage employee performance. In order to manage these challenges, performance management system has emerged as a powerful workforce management tool especially in new age growing multinational organizations. Along with the associated process, system and practices, well-implemented programmes are used strategically to create ‘value’ for the organization, managers and employees. Many organizations are redesigning their performance management system in order to make it more meaningful for business. Instead of a backward-looking process with once-in-a-year goal setting and feedback process, organizations are looking at a more forward-looking programmes and practices. The challenge is in designing and implementing performance management programmes that are real time, continuous, consistent and intuitive. More often, internal communication and training are the HRM levers that play an important role. This case of a fast-growing multinational IT firm, 1 undergoing change describes how performance management system was developed and implemented through use of communication and training. The article highlights the purpose, process, challenges and insights from developing and deploying the new performance management tool.

Influence of fibre orientation, tool geometry and process parameters on surface quality in milling of CFRP

Machining of highly abrasive carbon fibre reinforced polymer (CFRP) in the aerospace industry requires processes with excellent machining quality, sufficient tool lifetime and short cycle times. To reach these goals a detailed understanding of the physics of cutting and chip formation based on the tool geometry is necessary. This paper presents a fundamental study in milling of unidirectional CFRP focussing on variable process parameters, tool geometries and fibre orientations. A single-edged tool with cemented carbide inserts of variable macro geometry is utilised. The experiments are evaluated by 3D microscopy of the milled edges, detailed tool wear analyses and interpretation of cutting forces. The key conclusions from the experimental results are drawn to reach a better machining quality and increased tool lifetime. The delamination of top layer fibres from the ply below up to a certain distance from the milled edge, which depends on the forces at fibre cutting angle ϕ=90°, has been identified as main quality issue. Force and tool wear models based on the measurement data are presented.

Best Capacity Scale of Wafer Fabrication Based on Production Performance and Cost

Semiconductor manufacturing companies have constructed large fabs to enhance their competitive advantage. A large fab has many advantages, such as low cost, short cycle time and flexibility. Nevertheless, the advantages from the expansion of production capacity are not infinite, and a large fab scale increases the risk of production management. This work presents a model to determine the best capacity scale, where the production performance and cost are the major factors. Previous simulation experiments demonstrated that increasing the capacity scale improves the production cycle time significantly only when the utilization of the bottleneck machine is fixed. Therefore, the product cycle time is the major production performance index to determine the capacity scale of a fab. The GI/G/m queuing model is applied to build up the queue time equations of the bottleneck machine. Moreover, differentiation is used to find the number of bottleneck machines with queue times below the minimum required. The optimal number of bottleneck machines can be set based on the calculation result. Based on the performance result, the equipment cost per wafer can be taken into account for the final capacity scale determination. Additionally, an example is described and a simulation model is developed to validate the proposed model.