High-volume Production Process Research Articles

The efficiency of CUSUM schemes for monitoring the multivariate coefficient of variation in short runs process

Current monitoring technologies emphasize and address the issue of monitoring high-volume production processes. The high flexibility and diversity of current industrial production processes make monitoring technology for small batch processes even more important. In multivariate process monitoring, a broader applicability exists in multivariate coefficients of variation (MCV) based monitoring schemes due to the lower restriction of the process. In view of the effectiveness of MCV monitoring and with the aim to achieve further performance improvement of current MCV monitoring schemes in a finite horizon production, we additionally introduce two one-sided cumulative sum (CUSUM) MCV schemes. In the case of deterministic and random shifts, the design parameters of the proposed schemes are obtained via an optimization procedure designed by the Markov chain method and the corresponding performance is analysed based on different run length (RL) characteristics, including the mean and the standard deviation. Simulation comparisons with existing exponentially weighted moving average (EWMA) MCV schemes show that the proposed CUSUM MCV schemes are more efficient in monitoring most of the shifts, including the deterministic and random shifts. Finally, to demonstrate the benefits of the new monitoring schemes, a comprehensive case study on monitoring a steel sleeve manufacturing process is conducted.

Finding the Fingerprint of an PEMWE Electrolyzer Using Applied Machine Learning Techniques

The energy transition is picking up pace and renewable energy sources are playing an increasing role in our energy supply. The use of green hydrogen is considered an important energy carrier, to store renewable energy and allow many industries to decarbonize. There are different ways to produce hydrogen, whereas low-temperature proton exchange membrane water electrolysis (PEMWE) is one of the more mature electrolysis technologies. The benefits of proton exchange membrane water electrolysis (PEMWE) include the ability to deliver pressurized hydrogen and/or oxygen, operate using intermittent and renewable power sources, and have a reduced footprint. To evaluate the characteristic performance of PEMWE, the voltage/current relation is an important metric. The voltage/current relation is commonly represented in jV-curves. jV-curves contain relevant information, and any issues or out-of-specification performance can be observed immediately. The shape of the curve, and indicated values allow to interpret the performance of the PEWME cell. Nevertheless, proper interpretation of jV-curves and understanding of the source leading to the out-of-specification performance requires expertise.This study aims to evaluate jV-curves and identify faults by applying machine learning (ML) techniques. A conventional approach has been used to create the model. In the model the Nernst voltage, activation voltage on the anode, and the voltage losses due to ohmic resistance are modeled. Implementation of optimization algorithms allow to fit measured jV-curve to the model. Literature has shown relevant techniques to apply these kinds of ML techniques to electrolysis data, for example Particle Swarm Optimization and a modified Honer Badger algorithm. The application of ML to electrolysis data enables the opportunity to develop online monitoring and automated interpretation of data. In this study particle Swarm Optimization (PSO) has been implemented to fit the model to the jV-curve and find the unknown parameters. Those parameters are unique, depending on the performance of the electrochemical cell, and can be interpreted at the fingerprint thereof.The data shown in the figure has been measured on a single-cell material screener using Nafion 117 CCMs. Although both CCMs have been produced in the same batch, a difference between the measurements can be observed. The jV-curve of sample 1 shows performance as expected. This expected performance is characterized by its linear behavior above 0.5 A/cm2. Observing sample 2 shows an increase in voltage at increasing current densities compared to sample 1. This increase in voltage results in increased energy consumption and therefore a less efficient electrolysis process. Both CCMs are measured under comparable conditions. The anode and cathode pressure were during the both tests close to atmospheric, and the average cell temperature was kept constant at 333.15 K.Despite high volume production processes for coating and manufacturing, the origin of the difference in performance remains unknown. The application of automated data analysis allows for the immediate evaluation of the parameters at fault. The preliminary results show a discrepancy in the modeling parameters relevant to the sub-model describing ohmic losses. Furthermore, ML allows for the creation of data sets that contain experiences from the past. This can help to develop faster performance evaluation protocols by reducing testing activities. For future work, alternative algorithms have to be considered as well. Utilizing ML can enable the opportunity for online monitoring, predictive maintenance, and optimizing control strategies. Figure 1

Damage to inverse hybrid laminate structures: an analysis of shear strength test

Abstract Hybrid laminates with continuous fiber reinforcement, such as glass reinforced aluminium laminate (GLARE), aramid reinforced aluminum laminate (ARALL), or carbon reinforced aluminum laminate (CARALL), have been developed to increase the lightweight potential and fatigue resistance applied for aircraft structures. However, the use of thermosetting matrices imposes material limitations regarding recycling, malleability, and manufacturing-cycle times. The inverse hybrid laminate approach is based on a continuous fiber-reinforced thermoplastic matrix, in which a metal insert is integrated. For efficient manufacturing of the novel composites in high-volume production processes, conventional sheet metal–forming methods have been applied. It helped to reduce the cycle times and the costs of the forming equipment compared to currently used hybrid laminate-processing technologies. The present study analyzes the damage to the inverse hybrid laminate structures resulting from the interlaminar shear strength test. The tests were performed for eight laminate material configurations, which differed by the type and directions of the reinforced glass and carbon fibers in the polyamide matrix and the number of the fiber-reinforced polymer (FRP) layers in the laminates. Industrial computed tomography and scanning electron microscopy were used for analysis. Observed damages, including fiber–matrix debonding, fiber breakages, matrix fractures, interfacial debonding, and delamination in selected areas of the material, are strictly dependent on the laminate configurations. FRP layers reinforced by fibers perpendicular to the bending axis presented better resistance against fractures of the matrix, but their adhesion to the aluminum inserts was lower than in layers reinforced by fibers parallel to the bending axis.

59‐1: Invited Paper: From Lab to Fab: Challenges and Requirements for High‐Volume MicroLED Manufacturing Equipment

Availability of standard, high volume production tools and processes enabled the commercialization and commoditization of LCD and OLED. For microLED, the lack of processes standards and the proliferation of technology paths hinders the development of high‐volume manufacturing tools. This paper discusses the challenges for equipment manufacturers attempting to capture the microLED opportunity. While various technology bottlenecks remain, the microLED display industry can leverage on existing expertise and equipment from the display, semiconductor, LED and photonic industries to accelerate industrialization.

Evolution of properties of parts during MIM and sintering of recycled oxide particles

ABSTRACTMetal injection moulding (MIM) is an established process for high volume production of complex shaped metallic parts using commercially available feedstocks. The characteristics of parts after moulding, debinding, and sintering cannot be simply predictable from raw materials because the properties get altered with the process parameters and the corresponding levels of porosity during processing steps. In this study, physical properties, microstructure, and mechanical properties of the MIM parts have been characterised to understand the evolution of strength during various steps in MIM processing. Feedstocks with different binder loading show a considerable difference in physical as well as mechanical characteristics. During sintering of parts which have solid loading of grinding sludge, simultaneous in situ reduction and densification takes place, whereas only densification occurs in carbonyl iron parts. It is, therefore, possible to make complex shaped parts of different levels of porosity from downgraded shop floor metallic waste.

Process parameters for the high-scale production of alginate-encapsulated stem cells for storage and distribution throughout the cell therapy supply chain

Abstract With the ever-increasing clinical application of cell-based therapies, it is considered critical to develop systems that facilitate the storage and distribution of cell therapy products (CTPs) between sites of manufacture and the clinic. For such systems to be realized, it is essential that downstream bioprocessing strategies be established that are scalable, reproducible and do not influence the viability or function of the living biologic. To this end, we examined alginate-encapsulation as a method to heighten the preservation of human adipose-derived stem cells (hASCs) during hypothermic storage, and establish a scalable process for high-volume production. A drop-wise method for scalable alginate bead generation, using calcium as the cross-linker, was modified to enable the yield of up to 3500 gelled beads per minute. The effect of alginate concentration on the viscosity of non-gelled sodium alginate and the mechanical properties and internal structure of calcium-crosslinked alginate in response to different alginate and calcium concentrations were investigated. Mechanical strength was chiefly dependent on alginate concentration and 1.2% alginate cross-linked with 100 mM calcium chloride could withstand stress in the order of 35 kPa. Upon selection of appropriate parameters, we demonstrated the suitability of using this method for immobilizing human stem cells. Encapsulated hASCs demonstrated no loss in cell viability, and had a uniform distribution after high-volume production. Following storage, released cells were able to attach and recover a normal morphology upon return to culture conditions. Thus we present a scalable method for stem cell encapsulation and storage for application within the cell therapy supply chain.

Optimal control of an imperfect repetitive synchronised production environment

We develop optimal sublot policies to minimise total expected costs in a failure-prone two-stage, high-volume repetitive production process which manufactures batches of the same item over a long period of time. The first stage starts in control but may fail at an exponentially distributed random time, producing only good units before failure and only defective units afterward. Failure is detected upon encountering defective units in the second stage, at which time the first stage process may be restored to good condition. To enhance quality, a production lot in Stage 1 is subdivided into sublots which are transferred as soon as possible to Stage 2 for inspection and processing. We determine exact closed-form continuous solutions as well as an efficient algorithm for finding optimal integer sublots. We provide managerial insights as to what control mechanism would be adopted depending on the state of the production process parameters. [Received 14 May 2015; Revised 16 February 2016; Accepted 1 March 2016]

MECHANICAL AND SURFACE TOPOGRAPHY CHANGES DURING MECHANICAL TESTING OF DIFFRACTION OPTICAL ELEMENTS IN POLYMER

D evelopments in modern electronics, optoelectronics, industry of microsystems, and technology of biomedical devices are generating intense research interest. Creating polymer materials with well-defined physical and chemical properties is an important step towards building efficient devices. Replication technologies such as embossing, molding, and casting1,2 are highly attractive for the fabrication of surface-relief Diffractive Optical Element (DOE) microstructures.3,4 They have very high resolution, typically in the nanometer range, and allow the fabrication of large area, complex microstructure by low-cost, high-volume industrial production processes. Their use is already well established for gratings, holograms, and diffractive foils, and the extension to the fabrication of deeper and higher aspect ratio microstructure is underway. The combination of replication technology with other processes such as dry etching and thin film coating can also offer new possibilities in the design of DOEs suitable for mass production. Replication is expected to become a key technology for the microfabrication of DOEs in the future.5–7

Modelling and integration of customer flexibility in the order commitment process for high mix low volume production

With increasing product variety and dynamic demand fluctuation, manufacturing industry is moving towards a high product mix and low order volume production environment. Consequently, the order commitment process is becoming one of the most important processes for manufacturing firms to meet individual customer's needs with limited resources. However, demands for shortened delivery lead time, diverse customer requirements and more frequent customer orders have made the order commitment task more challenging. This paper attempts to tackle these new challenges by incorporating not only manufacturing flexibility but also flexibility from the demand side. Customer flexibility is characterised by customer indifference to certain product attributes and/or delivery schedules. Intuitively, with the consideration of customer flexibility, both manufacturers’ and customers’ interests can be better served since the solution space of matching demand and supply can be extended beyond the traditional domain purely from a manufacturing perspective. To this end, a systematic approach is developed to characterise and model customer flexibility. A mixed-integer-programming model is formulated to provide optimal order commitment decisions.

Investigation of an optical method for determining the average radius of curvature of micro-optical lenticular lens arrays

Micro-optical elements are of great importance in areas of optoelectronics and information processing. Establishing fast, reliable methods for characterization and quality control of these elements is important in order to maintain the optical performance in a high volume production process. We investigate an optical technique, applied to a polymer-based, injection moulded, lenticular array, but the method is also applicable for the tooling for these elements. The cylindrical lenses have feature sizes of 1–15 µm. The method is based on observation of the intensity distribution, which can be obtained in the far field of surface reflections resulting from a plane wave incident on the lenticular array. The intensity distribution of the diffraction orders is highly correlated with the shape of the illuminated lenslets. This is exploited to attain information about possible defects and shape variations that have arisen in the moulding process. The experimental results are compared with a model, based on the Fraunhofer approximation to the Huygens–Fresnel principle. Furthermore, the optical elements under investigation are probed using a scanning probe microscope. Hence, access to accurate topological data of the elements is attained and used to confirm the validity of the proposed optical technique.

Development of a stack having an optimized flow field structure with low cross transport effects

PEM fuel cells when operated on hydrogen from renewable sources are viewed as one of the most environmentally friendly energy conversion systems due to their high electrical efficiency. However, this advantage is depending on the overall system design, which is largely determined by the allowable operating conditions of the fuel cell stack itself. Besides the active materials, design and shape of the gas distribution zone have a significant influence on stack operation. In order to optimize overall system performance, a fuel cell stack with improved flow field design and performance was developed. An investigation on channel geometries led to a serpentine flow field with a moderate degree of parallelization and ribs with variable width to reduce cross transport effects. The resulting flow field subsequently has been modified slightly to allow a high volume production process. Summarizing, power as well as the degrees of H 2 and air utilization could be enhanced leading to a power density enhancement. Furthermore, weight reduction of end plates nearly by half using an improved end plate design led to an overall improved stack design.

Failure modes of ceramic rolling elements with surface crack defects

The properties of ceramics, specifically low density and high stiffness are of most interest to gas turbine and machine tool manufacturers. High hardness, low coefficient of thermal expansion and high temperature capability are properties also suited to rolling element materials. Much research over the past two decades on its structure, quality control and manufacturing techniques has produced ceramic materials which can seriously be considered for rolling contact bearing design. However, the difficulties of both sintering and machining the material may result in surface cracks. It is difficult to detect such cracks during high volume production processes and hence there is an important need to understand their influence and fundamental mechanism of the failures they cause. In the present study, the mechanisms of fatigue failure from surface cracks subjected to rolling contact have been studied experimentally and numerically. A three-dimensional boundary element model has been developed to study the failure mechanisms in rolling contact. The calculated results show that surface crack initiated fatigue failure involves fatigue crack propagation from original surface cracks and secondary surface crack formation when the crack reaches a critical condition. The secondary surface cracks play a dominant role in the formation of spalling fatigue failure. A comprehensive experimental study has been carried out to verify the numerical prediction. A modified four-ball machine is employed to perform rolling contact fatigue tests. Results from the experimental test are in good agreement with the results from the numerical analysis.

High Reliability of 0.1 µm InGaAs/InAlAs/InP High Electron Mobility Transistors Microwave Monolithic Integrated Circuit on 3-inch InP Substrates

The high-reliability performance of K-band microwave monolithic integrated circuit (MMIC) amplifiers fabricated with 0.1 µm gate length InGaAs/InAlAs/InP high electron mobility transistors (HEMTs) on 3-inch wafers using a high volume production process technology is reported. Operating at an accelerated life test condition of Vds=1.5 V and Ids=150 mA/mm, two-stage balanced amplifiers were lifetested at two-temperatures (T1=230°C, and T2=250°C) in nitrogen ambient. The activation energy (Ea) is as high as 1.5 eV, achieving a projected median-time-to-failure (MTTF) >1×106 h at a 125°C of junction temperature. MTTF was determined by 2-temperature constant current stress using |ΔS21|>1.0 dB as the failure criteria. This is the first report of high reliability 0.1 µm InGaAs/InAlAs/InP HEMT MMICs based on small-signal microwave characteristics. This result demonstrates a reliable InGaAs/InAlAs/InP HEMT production technology.

Failure of silicon nitride rolling elements with ring crack defects

Hot isostatically pressed silicon nitride rolling elements are currently used in hybrid rolling element bearings. Surface defects such as ring cracks are difficult to detect during high volume production processes and hence there is a need to assess their influence on the rolling contact performance of the material. An accelerated rolling contact fatigue bench test is used to examine failure mode and performance of silicon nitride rolling elements with and without surface ring cracks. The surface ring cracks are found on silicon nitride as purchased from manufactures and are not produced artificially. Experimental test results are presented with pre-test surface analysis using a dye penetration technique. Theoretical calculations of the lubrication regime, contact stress fields and finite element analysis are presented. Scanning electron microscopy is employed to observe the failure modes of the silicon nitride rolling elements.

Mass customisation

Mass production and personally tailored products are no longer considered opposite ends of the spectrum. The author recounts IBM's experiences in the days of the commodity PC. Once mass production relied on making all products exactly the same. `Customisation' is the opposite of this: making a product specifically for the individual customer. `Mass customisation' is a paradoxical idea that has only become possible with the arrival of modern manufacturing practices, such as just in time and total quality management. The author's interpretation of the phrase is simply: the process of reflecting very specific and varied customer requirements within a high volume production process without affecting lead time, cost or quality. Customers around the world, and in every conceivable activity, rightly demand more and more from their suppliers-impeccable quality, competitive prices, solutions as opposed to commodities and, of course, responsive and efficient after sales service. The author focuses on IBM's attempts to meet these demands in the arena of the personal computer.

An evaluation of forecast-based quality control schemes

High volume production processes and many processes using automated sampling technology yield process data which are autocorrelated. One technique proposed for monitoring autocorrelated data involves the application of the Individuals control chart to forecast residuals from an appropriate time series model of the process. This study examines the following issues concerning forecast-based monitoring schemes: (i) the affect of forecast recovery from step changes on the average run length (ARL) of control charts applied to forecast residuals (ii) the proposal of the cumulative distribution function (CDF) of the run lengths as an appropriate criterion for chart comparisons and (iii) the relative performance of the Individuals control chart, the Cumulative Sum (CUSUM) control chart and the Exponentially Weighted Moving Average control chart applied to forecast residuals using both the ARL and CDF criteria

Meeting the pattern definition challenge of 256MBit DRAM x-ray masks

Introduction The progress of ever increasing memory density continues to challenge the minimum linewidth and overlay accuracies of lithographic tools. Error budgets for the printed wafer continue to be driven downwards and in some manner must be apportioned between the stepper/wafer printing process and the manufacture of the master reticle image. In reduction steppers the former of these two processes usually takes the major share in order to give most latitude to the high volume production process leaving a reasonable tolerance for the magnified reticle manufacture. However, where X-ray stepper lithography is the selected printing technique its lx reticle technology requires a more even apportionment of the error budget if practical results are to be obtained. Table 1 shows the predicted requirement situation for a range of future memory products, both in the expected overall wafer level tolerances and in their apportionment where a lx reticle technology is used.

THE THICK-FILM STRAIN GAGE

The history and current status of thick-film strain gage technology are briefly reviewed, and data are presented on the performance characteristics of six different types of bonded piezoresistive strain gages. It is shown that the gage factor/thermal sensitivity characteristics make the thick-film strain gage technology attractive for general purpose applications. It is further noted that the low cost of a high-volume production process and a low-cost capsule packaging associated with the thick-film technology can result in low installed cost for measurement of pressure with very acceptable combined errors. 9 references.

Design and process sensitivity of a two-stage 6—18-GHz monolithic feedback amplifier

The design of a 6-18-GHz two-stage monolithic feedback amplifier is discussed, and the critical process and FET parameters are identified. Variations in circuit performance experienced during a pilot production run are correlated with the predictions of a sensitivity analysis. Five circuit model parameters were selected for study: substrate height, GaAs sheet resistance, gate-source capacitance, transconductance, and drain-source resistance. Measured results show the importance of substrate height and sheet resistance in the control of gain flatness. An example on-slice RF performance distribution is presented, showing the suitability of the circuit and fabrication process for high-volume production.

Design and Process Sensitivity of a Two-Stage 6 - 18-GHz Monolithic Feedback Amplifier

The design of a 6-18-GHz two-stage monolithic feedback amplifier is discussed, and the critical process and FET parameters are identified. Variations in circuit performance experienced during a pilot production run are correlated with the predictions of a sensitivity analysis. Five circuit model parameters were selected for study substrate height, GaAs sheet resistance, gate-source capacitance, transconductance, and drain-source resistance. Measured results show the importance of substrate height and sheet resistance in the control of gain flatness. An example on-slice RF performance distribution is presented, showing the suitability of the circuit and fabrication process for high-volume production.