Cycle Time Reduction Research Articles

Effects of high frequency vibratory finishing of aerospace components

Vibratory finishing is extensively utilized for surface engineering applications particularly in the aerospace industry. Commercial vibratory finishing operations occur at a frequency range of 15 Hz to 50 Hz. An experimental investigation on the effects of high frequency on surface roughness and process cycle time is reported with the objective of providing a deeper insight into high frequency vibropolishing. The study was orchestrated with the aid of a modified commercial vibratory finishing bowl delivering frequencies up to 75 Hz. Flat Ti-6Al-4V test pieces were subjected to vibropolishing at conventional bowl frequency of 50 Hz and high frequency of 75 Hz to demonstrate the effects of increasing frequency in vibratory finishing. Investigations showed up to 80 percent cycle time reduction when operating frequency was increased to 75 Hz. Statistical tests and force sensors were incorporated to provide an in-depth analysis of the experimental results. Consequently, it was concluded that while high frequency of vibrations had a positive impact on the process cycle time, the orientation of a work piece had negligible influence.

Fusion joining of thermoplastic composite wind turbine blades: Lap-shear bond characterization

Wind turbine blades are typically manufactured from a small number of components which are bonded together with an adhesive. Over the life span of a wind turbine, the static and fatigue loads in varying environmental conditions can lead to cracking and/or debonding of the adhesive joints, ultimately leading to blade structural collapse. The objective of this work is to investigate fusion joining of wind turbine blades manufactured using thermoplastic resin. Thermoplastic resins for wind turbine blades can reduce cycle times and energy consumption during manufacturing and facilitate end-of-life recycling and on-site manufacturing. Additionally, fusion joining of these materials can replace adhesives, resulting in stronger and more robust blades. This work showed that, compared to typical adhesives used in wind turbine blades, fusion welding resulted in an increase in both the static and fatigue lap-shear strength as compared to bonded thermoplastic composite coupons. This initial coupon-scale research suggests that there is potential for developing fusion welding techniques for full-scale wind turbine blades.

Lean Six Sigma for Quality and Performance Improvement of POH Process of Wagon Wheel CTRB

Due to high competition in present world, every end user of a product demand their products to be delivered to them on time with good quality. Hence it is an objective of every industry to satisfy their customer requirements. In the long run, this can be achieved by continuous and constant process improvements. Lean Six Sigma is an overall quality improvement approach combining and capitalizing the strengths of Six Sigma and Lean Management improvement programs. In CTRB periodic overhaul, several process steps and workplaces are required for the job, the movement of inventory between the workplaces can be very time consuming unless it is suitably planned. The major areas that need great attention in this system are WIP (work in process), Takt time and process variability. In this study, focus is on the application of lean tools and techniques with their principles coupled with six sigma DMAIC methodology. The objective of this study is to identify the best possible tools and techniques to tackle premature failure of CTRBs whilst in service due to early presence of defects which are closely associated to the POH process. It also discusses the methodology generally adopted, tools and techniques used and benefits obtained. By mapping current state of the POH process and takt time, future state improvement can be done in order to reduce cycle time using Lean tools such as Poke-Yoke, Jidoka, 5S, SMED

Polyether ether ketone (PEEK) and its manufacturing of customised 3D printed dentistry parts using additive manufacturing

BackgroundIdentified research articles on Polyether ether ketone (PEEK) and its application in dentistry. Further identified the direction of evolution of this material through additive manufacturing (AM) in the field of dentistry. Materials and methodsPEEK is one of the suitable thermoplastic polymers which is biocompatible for the human body. We have identified related research articles through Scopus. A bibliometric analysis helped to achieve the targeted research objective. ResultsThrough Scopus search, 46 research articles were identified by using keywords as “PEEK” “Dentistry”. Doctors and scientists are using PEEK material in medical, and other associated fields to fulfil extensive requirements of customisation. Nowadays, PEEK is also being experimented in dentistry for developing implants and associated requirements. Therefore, by using AM technologies, PEEK-based implants provide a perfect match replica in lesser time and cost. Further, this paper identifies significant challenges of using this material with AM for dentistry. In the last, the paper identifies ten important application of PEEK in AM for dentistry. ConclusionAdditive manufacturing shows a significant achievement in the design & development of dental implants, tools and devices using PEEK material. It helps in reduction of product development cycle time, cost, weight with improved quality of implants and helps fulfil various challenges faced in dentistry. This innovative technology works as concept generation and is easy to make a required modification for a product used in dentistry. Design and development of dentistry tool are done easily such as manufacturing of any implants for surgical planning and analysis whether the surgery will succeed or not. Therefore, this technology has application in the production of customised PEEK-based orthodontics, crowns, bridges, night guards and prosthodontics implants.

Reduction of cycle times in injection molding of PLA through bio-based nucleating agents

An approach to reduce cycle times in injection molding of poly (lactic acid) through the use of bio-based nucleating agents is presented. Talc is commonly used as nucleant and will be used as the reference in this study. The other investigated additives are kraft lignin, lignosulfonate, and carbon black. This is an in-depth study of certain bio-based nucleating agents for use with poly (lactic acid) under various processing conditions.Bio-based compounds of poly (lactic acid) and different nucleating agents were produced via twin-screw extrusion. Subsequent injection molding yielded standard samples for tensile testing; cycle times were recorded during injection molding. Thermal and mechanical testing showed direct dependence upon the degree of crystallinity in the matrix polymer. The ability of certain bio-based nucleating agents (e.g. kraft lignin) to reduce the cycle time in injection molding was proven.

Reaction: Size Distribution in Olefin Block Copolymers: Not Bad at All

Hongyu Chen completed his PhD in macromolecular science at Case Western Reserve University in 2010. He is a fellow of the Dow Chemical Company, where he focuses on developing new products. He is also a fellow of the American Physical Society and American Chemical Society. Valeriy Ginzburg completed his PhD in polymer physics at the Moscow Institute of Physics and Technology in 1992. He is a senior scientist at the Dow Chemical Company and a fellow of the American Physical Society.

Cycle Time Reduction in Manufacturing Processes

Cycle Time Reduction in Manufacturing Processes

Design of Advanced Injection Mold to Increase Cooling Efficiency

Cycle time reduction is one way to increase the energy efficiency of the injection molding production process. For injection molding, conformal cooling channels can be considered as a potential solution for obtaining a uniform temperature distribution in the mold, which results in a shorter cooling time and better quality of the molded part. However, the design and manufacture of optimal cooling channels is a challenge due to their complex geometry and heat transfer. This paper presents a method to maximize the efficiency of a conformal cooling channel made by 3D printing technology. The combination of analytical formulas and CAE simulation is applied to design optimal cooling channels in terms of cooling efficiency and manufacturability. An actual case study is introduced and analyzed to demonstrate the benefit of the conformal cooling channel and the robustness of the proposed design method. The results show that the cooling time and cycle time can be reduced more than 50% when molding a plastic product that is difficult to cool by conventional straight-drilled cooling channels. This is a great contribution to an environmentally friendly manufacturing technology.

Lean production theory-based simulation of modular construction processes

Abstract One way to encourage adoption of prefabrication and off-site manufacturing (OSM) techniques, such as modular construction, is to improve the efficiency of site operations, which makes the technology more attractive to non-adopters. Lean principles have been widely applied to improve the productivity and efficiency of construction operations, while simulation augments Lean theory by allowing its benefits and issues to be analyzed quantitatively before actual implementation. Thus, this study aims to conduct a detailed simulation study of modular construction operations, otherwise known as Prefabricated Prefinished Volumetric Construction (PPVC) in Singapore. In contrast with existing research, which are frequently focused on the barriers and drivers to the adoption of prefabrication, this study will provide and evaluate recommendations to improve modular construction efficiency through application of Lean concepts. A detailed baseline (As-Is) simulation model of an ongoing PPVC project case study was first developed. Lean Construction principles were then applied to the baseline simulation model. Key Lean Construction principles and concepts implemented includes Total Quality Management, E-Kanban based Just-In-Time deliveries, cross training and the use of construction robotics. Lean (To-Be) simulation models were developed based on the Lean Construction principles. The outputs from the baseline and Lean models were compared to assess the impact of the proposed improvements. The findings demonstrated that through the application of Lean concepts, reductions in cycle time and process time, and increases in process efficiency and labor productivity can be achieved. The case study also provides a detailed description of the simulation approach, which is a useful reference for future application of simulation in offsite construction research.

Synergistic Effect of Talc and Titanium Dioxide on Poly(lactic acid) Crystallization: An Investigation on the Injection Molding Cycle Time Reduction

Injection molding cycle time is one of very important parameters relating to the plastic production rate. In neat poly(lactic acid) (PLA), it requires more than 25 min to obtain its half crystallinity (t1/2). This indicates that the injection molding of neat PLA with high degree of crystallinity (Xc) and high production rate is impossible. This research aims to increase the crystallization rate of PLA by combining two inorganic fillers namely; titanium dioxide (TiO2) and talc. Differential scanning calorimetry (DSC) study indicated that the t1/2 of PLA decreased from 27 min to < 81 s, while the Xc increased by around 16% with the adition of TiO2. Modifying PLA with talc was found to reduce t1/2 down to 36 s and the Xc increased from 0.92 to 20% only at a heating rate of 1 °C/min. The combination of talc and TiO2 was significantly increased the Xc for all cooling rates applied. Synergistic crystallization behavior was clearly observed when TiO2 was added to PLA/talc for all TiO2 concentrations. Minimum t1/2 of 18 s was observed together with the increased Xc by around 26% when TiO2 was added to PLA/talc at 3 wt%. This reduced the injection cycle time from around 28 min, in neat PLA, down to 68 s at this TiO2 content. With the presence of talc and TiO2, the flexural modulus of the composites was improved significantly.

Improving municipal solid waste compost process by cycle time reduction through inoculation of Aspergillus niger.

A lack of understanding about the effect of microorganism inoculation on compost production and relatively expensive downstream processing are the main obstacles towards an economic compost production. Our work tries to fill this gap. For this, influence of inoculation on the composting of organic fraction of municipal solid waste (OFMSW) to produce compost with higher agronomic value was evaluated. Three similar aerated bioreactors (A, B and C) with the same size and shape in laboratory scale designed. Reactor A was inoculated with the Aspergillus niger IBRC-M 30095, reactor B was inoculated with old compost and reactor C was used as a control. During the composting process temperature, moisture, pH, and electrical conductivity (EC) were evaluated. Also, the ratio of carbon to nitrogen (C/N) and germination index (GI) were measured in during process to evaluate compost maturity. The results of this study showed that the C/Ns decreased to about 63.37%, 59.6% and 46% for bioreactors B, A and control, respectively. Also maximum GI and temperature reached to about 138% and 59°C in reactor B. Furthermore, our results showed that inoculation with this microorganism reduces process time to 18days that is better than the results of other researchers and thus results in cost savings. However, we think, Aspergillus niger is appropriate candidate for compost production as a model. Graphical abstractSchematic diagram of experimental reactors: Reactor A was inoculated with the Aspergillus Niger IBRC-M 30095, reactor B was inoculated with old compost and reactor C used as a control without inoculation; (1) composting tank; (2) air compressor; (3) gas flow meter; (4) air regulator; (5) thermal probe; (6) exhausted gas; (7) mixer; (8) effluent; (9) moisture content probe; (10) sampling; (11) electric motor; (12) pump.

Mechanical behaviour modelling and finite element simulation of simple part of Ti-6Al-4V sheet under hot/warm stamping conditions

In order to reduce production costs and environmental impact, the cycle time reductions associated with a decrease in temperature levels are relevant. This study focuses on the behaviour modelling of Ti-6Al-4V alloy at temperatures between 400 °C and 500 °C in order to obtain greater formability than at room temperature, whilst remaining below SPF conditions to reduce tool, workshop and energy costs. Mechanical tests are conducted to identify elasto-viscoplastic model parameters. They use displacement field measurements obtained by Digital Image Correlation (DIC) and based on innovative surface preparation patterns adapted to high temperature exposures. Different material parameters are identified to define a model that is able to predict the mechanical behaviour of Ti-6Al-4V alloy under hot/warm stamping conditions. Then, an omega shape forming test is developed to validate the behaviour model. Finally, the experimental results are compared with numerical simulations which require the implementation of the behaviour model formulation into an FE code.

Application of vendor rationalization strategy for manufacturing cycle time reduction in engineer to order (ETO) environment

PurposeThe purpose of this paper is to demonstrate the application of vendor rationalization strategy for streamlining the supplies and manufacturing cycle time reduction in an Indian engineer-to-order (ETO) company. ETO firms are known for a large number of vendors, co-ordination hassles, rework problems and its impact on cycle time and operational excellence.Design/methodology/approachThe research demonstrates the case-based application of Kraljic’s matrix for supply and leverages items, on-the-job observations, field visits, discussions and analysis of supplies reports.FindingsThe study guides on the rationalization of supplies and the necessary strategic alignments that can significantly reduce supply risk, costs, manufacturing and delivery cycle time along with co-ordination hassles. The study depicts the challenges of ETO environment with respect to supplies, and demonstrates the effectiveness of vendor rationalization application for the case company and weaknesses of commonly practiced vendor management approaches.Practical implicationsTo be competitive, companies should rationalize supply items and vendors based on the nature of items and their subsequent usage by applying Kraljic’s matrix-based classification. The immediate implication of vendor rationalization is misunderstood as reducing supply base, but it does much more and includes review of supplies, nature of items and strategic alignments, leading to win-win situation for company and suppliers.Originality/valueFor the rationalization of supplies, while procuring and dealing with vendors, executives should envisage engineering nature of components, considering cross-functional requirements and integration of components in context to ETO products/projects environments. There is a dearth of studies focusing on vendor rationalization aspects in ETO setups in fast-developing country context.

A new conformal cooling lattice design procedure for injection molding applications based on expert algorithms

The paper presents the geometric design of a new lattice element of conformal type integrated into the cooling system of an injection mold. The geometric variables of this element are parameterized and are included in the design of the mold cooling system so that it can be valid for any type of geometry of plastic parts. Similarly, a physical model is presented to analyze the energetic behavior of the cooling lattice. Through the application of expert-type optimization algorithms to the presented physical model, the geometrical variables of the cooling lattice are dimensioned as well as the technological variables that govern the cooling phase of the plastic part. This methodology has been applied to four plastic parts with different geometrical characteristics. The results obtained have been compared with numerical simulations carried out by means of CFD-type software for plastic parts analysis, concluding that the new cooling lattices are adapted to the design criteria of an optimal cooling system. The new cooling lattices improve, in turn, the efficiency of thermal exchange in the cooling phase for plastic parts with large concavities, fine details, internal turrets, and housings. A simplified model focused on the energy analysis of a single cooling cell has been defined, which allows us to evaluate the thermal exchange between the cooling lattice and the plastic part, avoiding the computational complexity in the generation of the discrete mesh of the mold inserts. Similarly, in order to guarantee the structural safety of the cooling grids, a numerical mechanical analysis of the structural behavior of the injection mold insert under the most unfavorable contour conditions during the injection process has been carried out. The new conformal system presented in the paper does not require expert designers for its dimensioning, considering it as an adequate tool for reducing the overall design time of the mold while allowing the manufacturing process to be more efficient, reducing cycle time, and increasing the quality of the parts produced.

GISS Technology: Principle and Applications in Die Casting

In the past, there have been a lot of effort to solve gas and shrinkage porosity defects in die casting. The common solutions are vacuum technology, jet cooling technology, and application of squeeze pins. However, these solutions often increase the die casting production costs. A new solution that has recently been introduced worldwide is GISS Technology. This technology applies the superheated slurry casting process. Gas and shrinkage porosity defects can be reduced. Furthermore, the production costs are lowered due to die life extension, cycle time reduction, melting energy reduction, and lubrication usage reduction. This paper describes the principle of GISS Technology, and selected applications and case studies are also be presented.

Single-Pass Cladding Process Using Hot-wire Gas Metal Arc Welding Technique

The aim of this study is to improve cladding process productivity by high production rate with low dilution process by specifying technique as hot-wire GMAW process. The base metal of carbon steel A516 Gr70 was cladded by austenitic stainless steel 309LSi for creating a buttering layer and stainless steel 308LSi for hot-wire filler for topping a cladding layer in a one-pass run. The studied parameters this experiment consist of the feeding ratio of hot wire feeding speed per GMAW wire feeding speed and travel speed. Welding phenomenon during welding was observed by CCD camera with specifying the optical device to see the appropriate condition. The result showed the hot-wire GMAW cladding process could reduce cycle time 3.5 times compare with conventional FCAW cladding process. Moreover, dilution of this process could decrease lower than 15% with acceptable FN 3 on the top of weld surface. Therefore, single pass cladding process achieved by using this method with low dilution by still keep microstructure capability.

Microwave-assisted extraction of the gallic acid biomarker from Acacia arabica bark followed by HPLC analysis

An efficient and fast microwave-assisted extraction (MAE) technique was developed for extracting gallic acid as an indicative biomarker for the quality control of Acacia arabica bark. The MAE technique was optimized and compared with other conventional extraction techniques. The optimal conditions of MAE were 20% methanol as solvent, solid/liquid ratio 1:40 (g/mL), irradiation power 20% and two extraction cycles, 5 min each. The proposed extraction technique produced a maximum yield of 10.59 (mg/g) gallic acid in 10 min, which was 1.03 and 1.15 times more efficient than 6 h of heat reflux and 24 h of maceration extraction, respectively. This high yield, along with saving of time, energy, and solvent would position MAE as a valuable and cost-effective technology suitable for today's highly competitive industries, with growing demand for increased productivity, improved efficiency, and reduced cycle time. Moreover, a new high-performance liquid chromatography method was developed and validated for the determination of gallic acid in Acacia arabica bark extract. The method was found to be rapid, sensitive, accurate, precise, and robust. The method showed good linearity over concentration range 1-100 (µg/mL) with LOD 16.08 (ng/mL) and LOQ 48.73 (ng/mL). The average recovery obtained using standard addition technique was 100.36% with a low value of RSD% (1.19%) indicating the accuracy of the proposed method for determination of gallic acid in Acacia arabica bark extract.

Case Study: Modeling of the cycle time reduction in a B-Pillar hot stamping operation using conformal cooling

Increasing demand in the automotive industry for high strength and lightweight components has led to the promotion and development of hot stamping processes. The integration of adaptive or conformal cooling channels within the stamping tools opens the possibility to increase the cooling performance of the process, thus improving not only the quality of the final part but also shortening the process cycle. The present work aims to evaluate the thermal field of the stamped blank, as well as to quantify the cycle-time reduction and the process efficiency in the hot stamping of a B-pillar type geometry when using conformal instead of straight-drilled cooling channels. To that end, a transient thermal simulation of the hot-stamping process is performed by means of ANSYS workbench software. Thirty consecutive stamping operations, including the intermediate cooling stages required for the blank unloading and loading, are simulated in order to ensure that the tools have reached a thermally stable regime. In this situation, the temperature differences in the tools, as well as their influence in the cooling process of the blank have been studied. Based on the obtained results, it is concluded that conformal cooling enables to reduce the cycle time by 3 s when compared to the straight-drilled tool, which involves a 15% process performance increase. Besides, positioning the conformal cooling channels closer to the surface implies a 5 s cycle-time reduction with regard to the straight-drilled tool, which leads to a 25% process-time reduction, and therefore, productivity increase.

Production flow control through the use of reinforcement learning

This paper introduces a new research focus for the problem of flow control. Most of the research until this point in this topic comes in the form of heuristics and flow control protocols, from which we can highlight Kanban and CONWIP. These protocols have as common ground the fact that both impact flow by limiting the amount of WIP (work in process) that circulates through a production route. These limits are not static in a sense that one limit defined for a given period will not suffice for all possible conditions the future may entail. Therefore, we need strategies to find which values for the WIP caps are best (according to an optimization target), given a production system state and a customer demand level. We propose the use of a Reinforcement learning (RL) agent and introduce the problem within the framework of a reinforcement learning problem, showing that for a simulated system it is possible to reduce WIP levels up to 43% without losses in throughput (TH). As an introduction to the flow control problem comparisons between push and pull systems are made resorting to the use of discrete event simulations. We simulated a CONWIP and a push protocol and comparisons are made in terms of cycle-time, throughput and customer lead-time. The work points-out that within the field of industrial management research terms such as cycle-time, customer lead-time, and lead-time are sometimes used interchangeably, which may lead to unnecessary confusion and hindered understanding of the subject matter. Specifically, we show that cycle-time reduction does not lead directly to customer lead-time reduction in a make to order environment.

Rapid Multifunctional Composite Part Manufacturing using Controlled In-situ Polymerization of PA6 Nanocomposite

Currently, mass composite manufacturing is dominated by the fiber-reinforced thermosets due to the ease of its processing. However, the addition of multifunctionality to the thermoset composite requires an additional step of manufacturing. This work presents the single-step rapid manufacturing of bespoke designed multifunctional nanocomposite PA6 components. In this method, firstly, the liquid PA6 nanocomposite containing inorganic nano-inclusions was infused into a glass or carbon fibre matrix placed within the mould. Subsequently, the multifunctional composite component was formed via the anionic in-situ synthesis route. The flexibility of this method presented is akin to that of a polymer moulding process, which ensures a reduction in the manufacturing cycle times and increases the production efficiency of the bespoke component. The in-situ reaction is optimised by setting the specific volume of the activator, initiator and including polymer chain terminator, PEG. To prepare the polymer with at least 50% and above crystallinity, the most suitable activator-initiator combination was found to be 0.143 ml and 0.096 ml respectively, with 0.1 g of PEG-6000 for 5 g sample preparation. Such thermoplastic-based components can be easily recycled, present better impact resistance and can be easily formed or fused with heat; eliminating the cost and time associated with the assembly of composite part, unlike thermoset components.