Dynamic flexibility metrics for capability and capacity

In production environments, such as Flexible Manufacturing Systems (FMSs), the schedule can be disturbed by the occurrence of unplanned events. Machines stop for major failures, maintenance, tool changes due to wear, or tool reassignments. The rescheduling process, however, can be costly. In this study, a dynamic measure of flexibility which helps to determine an appropriate time for rescheduling an FMS has been defined and investigated. Flexibility is defined as a function of Capability and Capacity. Accordingly, two metrics have been developed to monitor the capability and capacity efficiency of each machine in the system for responding to the dynamic system status. The value of each metric falls between 0 and 1 at all times. Higher values in the capability metric mean better machine selection and part distribution strategies among the machines. Higher values for the capacity metric mean higher machine utilization in the production plan. Based on the interaction between the metrics and their respective behavior in the system, four states have been identified and characterized. Simulations of various scenarios can be used to demonstrate the use of these metrics for monitoring FMS operations and determining appropriate times for rescheduling and tool reassignment.

Mass customization of travel packages: data mining approach

This article employs a mass customization strategy to design travel packages that minimize the operation and processing costs for the service provider on one hand, while aligning the components of the packages to maximize customer satisfaction on the other. Data mining is used to identify rules of association to develop this model. Hidden relations in the massive travel agencies’ databases are revealed by using the association rules technique to customize travel packages according to customers’ requirements. This approach leads to fewer, but more manageable and popular travel package promotions. The overall package selection problem is modeled as an integer program that minimizes costs of operation and processing. Two different solution approaches were used: a mathematical modeling language approach and a heuristic algorithm approach. An illustrative numerical example based on a synthetic data set is also presented.

High-Temperature Tribological Properties of 2-Substituted Imidazolium Ionic Liquids for Si3N4-Steel Contacts

Novel ionic liquid lubricants based on monocationic and dicationic 2-substituted imidazolium ionic liquids were synthesized and evaluated as lubricants at 250 °C. Results showed that both monocationic and dicationic 2-substituted imidazolium ionic liquids with bis(trifluoromethylsulfonyl)imide anion have excellent friction-reducing and anti-wear properties at high temperature, which is ascribed to the high chemical and thermal inertness.

Synthesis of dicationic symmetrical and asymmetrical ionic liquids and their tribological properties as ultrathin films

A new series of novel dicationic symmetrical and asymmetrical ionic liquids (ILs) consisting of tributylalkyl phosphonium and alkylimidazolium were synthesized. Their tribological properties in the form of spin-coated ultra-thin films sliding against AISI-52100 steel ball were studied in a ball-on-plate configuration on a Universal Micro-tribometer-2MT tester, using perfluoropolyether (PFPE) and normal ILs as comparisons. The best result is obtained for asymmetrical 1-(1-tributylphosphine-yl-hexyl)-3-methylimidazolium dihexafluorophosphate, which has very high decomposition temperature-about 450 °C and good tribological properties.

Assessing capacity scalability policies in RMS using system dynamics

This paper presents a model for assessing different capacity scalability policies in Reconfigurable Manufacturing System (RMS) for different changing demand scenarios. The novelty of this approach is two fold: (1) it is the first attempt to explore different capacity scalability policies in RMS based on multiple performance measures, mainly scaling rate, Work In Process level, inventory level and backlog level; and (2) the dynamic scalability process in RMS is modeled for the first time using System Dynamics. Different policies for capacity scalability for various demand scenarios were assessed. Numerical simulation results obtained using the developed capacity scalability model showed that the best capacity scalability policy to be adopted for RMS is dependent on the anticipated demand pattern as well as the various manufacturing objectives. The presented assessment results will help the capacity scalability planners better decide the different tradeoffs between the competing strategic and operational objectives of the manufacturing enterprise, before setting the suitable capacity scalability plan parameters.

Defects tracking matrix for mass customization production based on house of quality

The vision of mass customization has driven a movement toward low volume, high variety mass customization production (MCP) at low price. However, defect identification and defect tracking in such systems are extremely difficult because of the frequent reconfiguration needed by the number of different part types and the interruption of the information flow about quality with each reconfiguration of the system. It is important to quickly rebuild quality information flow with MCP system’s reconfiguration synchronously. This paper introduces a defect tracking method based on Quality Function Deployment for every MCP system module. A defects tracking matrix (DTM) based on the House of Quality directly connects manufacturing technologies with quality defects inside a MCP module. Each MCP reconfiguration requires the DTMs’ rearrangement and DTM-chain is proposed. A dynamic reconstructing algorithm synchronizes the DTM-chain with each MCP reconfiguration. A case study demonstrates the usefulness of the DTM and DTM-chain.

A modeling approach for evaluating capacity flexibilities in uncertain markets

The flexibility of production capacities is a means for coping with the challenges in today’s market environment, especially when dealing with strong fluctuations in customers’ demands. The reliable planning and evaluation of these capacities and their inherent flexibilities are considered an important task for many companies. This paper presents a capacity/cost model that considers the impact of market uncertainties and the corresponding capacity flexibilities. It proposes a demand forecasting method, a modeling approach for capacity-related flexibilities and the analysis of the economical correlation between available and required capacities. Based on this, capacity planning can be optimized using this model. The different steps of applying this modeling approach are illustrated with the aid of an example.

Modeling customized product configuration in large assembly manufacturing with supply-chain considerations

Dynamic variability in low-volume and highly customized products of a large assembly manufacturing system with an integrated supply chain has been very challenging to capture. Design and product configurations most likely impact outcomes of such broad variability. This article presents a framework to encompass this completely integrated system for using discrete event simulation as a modeling method. The system modeling framework addresses factors including customized configuration attributes and individual customer-preferred considerations for customized configurations. The framework is intended to aid decision-making concerning cost and schedule impacts associated with customization options chosen throughout the supply chain. A real-world example drawn from aerospace is included to demonstrate and validate the operational capability of the proposed framework.

Impact of ramp-up on the optimal capacity-related reconfiguration policy

This paper presents an optimal solution, based on Markov decision theory, for the problem of optimal capacity-related reconfiguration of manufacturing systems, under stochastic market demand. Both capacity expansion and reduction are considered. The solution quantitatively takes into account the effect of the ramp-up phenomenon, following each reconfiguration, on the optimal policy. A closed-form solution is presented for when product demand is independently and generally distributed over time. A real case concerning a flexible manufacturing line in the automotive sector is shown, to prove that ignoring the ramp-up effect in the decision process can lead to significant increases in overall costs.

Dynamics of Vapor-phase Organophosphates on Silicon and OTS

We have performed a quartz crystal microbalance (QCM) study of the uptake and nanotribology of organophosphate (tricresylphosphate (TCP) and t-butyl phenyl phosphate (TBPP)) layers adsorbed from the vapor phase onto amorphous and polycrystalline silicon and octadecyltrichlorosilane (OTS) treated silicon substrates. The materials were selected for their relevance to MEMS applications. About 3–5 monolayer-thick organophosphate films are observed to form readily on both silicon and OTS-treated silicon. The coatings moreover exhibit mobility in the form of interfacial slippage or viscoelasticity in response to the oscillatory motion of the QCM, implying that enhanced tribological performance may be expected in MEMS applications.

Mass customization: manufacturing issues and taxonomic analyses

As the field of mass customization (MC) attains the status of a mature discipline, two significant research deficits stand out. First, a through metareview of the entire body of MC research that looks at the application value and rigorousness of research is overdue. Second, manufacturing issues, especially those pertaining to quality and the supply chain have been largely ignored. This issue is dedicated to both of these important areas of research. The conclusion with regards to the status of the MC field is that it is currently vibrant, with growing research volume and applications. The manufacturing issues dealt with in this issue are strategically important, dealing with quality and customization issues. The work on quality is the first of its kind: it seeks to generate a defect-tracking matrix consistent with product configurations, enabling agile identification of defects in a mass customization environment. The use of discrete event simulation to deal with the dynamically evolving customized demand so as to minimize cost and schedule disruption is innovative, timely, and profound.

The Leiden MEMS Tribometer: Real Time Dynamic Friction Loop Measurements With an On-Chip Tribometer

On-chip MEMS tribometer devices until now have been much less sophisticated for dynamically sensing frictional forces than their FFM (friction force microscope) counterparts. In this article, we present a MEMS-based tribometer that can be used to measure dynamically, on-chip and in-situ, the frictional properties of MEMS-scale contact geometries. The device provides the first FFM-like friction loops with contacting MEMS sidewall surfaces. Depending on the normal load two regimes of operation are identified. At low and intermediate loads, the frictional behaviour reflects wear-less relative motion of the silicon oxide surfaces of the MEMS device and we observe repeatable, irregular stick-slip behaviour, related to the surface roughness. At very high loads, wear causes changes in the topography of the contacting surfaces.

Measuring the effectiveness of a mass customization and personalization strategy: a market- and organizational-capability-based index

The research of Kumar (Int J Flex Manuf Syst 16(4):287–312, 2004) is expanded to develop a methodology that measures the effectiveness of a mass customization and personalization strategy using a mass customization and personalization effectiveness index. This index extends Kumar (2004) in three significant ways: (1) it encompasses both service and manufacturing companies, (2) the assessment of product customization considers that customers assign different weights to different product features, and (3) the index captures the impact of both market perception and system capabilities. Three different measures are proposed. Which is appropriate should be a function of a particular company’s parameters. The circumstances under which each measure is best is a subject for future research. The validation and reliability of this index and these measures are also issues that should be addressed by future research.

Interpretation of experiments on ZDDP anti-wear films through pressure-induced cross-linking

We review a recently developed molecular-level theory for the formation and functionality of zinc dialkyldithiophosphate anti-wear films [N. J. Mosey, M. H. Müser and T. K. Woo, Science 307 (2005) 1612]. This theory is based on the idea that pressure-induced cross-linking leads to chemically connected networks. The formation of cross-links modifies the mechanical properties of the films such that wear inhibition may be enhanced. Furthermore, the networks remain intact upon release of the pressure, which resists flow of the film out of the contact area. The ability of the theory to account for a diverse body of experimental data related to anti-wear additives and films is discussed. Routes towards the development of new AW additives are also suggested on the basis of the theory.

The Influence of Anchoring-Group Structure on the Lubricating Properties of Brush-Forming Graft Copolymers in an Aqueous Medium

We have compared the lubricating properties of two different PEG-grafted, polycationic, brush-forming copolymers to gain a deeper understanding of the role of the polyionic backbone in the lubricating behavior of such materials, when used as additives in aqueous lubricant systems. Previously, poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) has been shown to adsorb onto oxide surfaces from aqueous solution and substantially lower frictional forces. Poly(allylamine)-graft-poly(ethylene glycol) (PAAm-g-PEG), which also has a polycationic backbone, has been synthesized in several different architectures, and its performance investigated via adsorption tests, rolling- and sliding-contact tribometry, and the surface forces apparatus. These tests show a clear reduction of friction forces with PAAm-g-PEG compared to water alone. However, when compared with PLL-g-PEG, while PAAm-g-PEG copolymers did not adsorb to the same extent or exhibit as high a lubricity in sliding geometry, they showed a similar lubricating effect under rolling conditions. The difference in the chemical structure of the backbones, especially the flexibility of the anchoring groups, appears to significantly influence both the extent and kinetics of polymer adsorption, which in turn influences lubrication behavior.

Aligning demand and supply flexibility in custom product co-design

Flexibility of supply and demand is essential for successful implementation of a mass customization strategy that delivers sustained competitive advantage. Supply flexibility, i.e., a choice of alternative products designed to perform the same basic function, is made possible by the range of capabilities available in flexible and agile manufacturing systems and in supply chains. Demand flexibility is derived from the degree to which a customer is willing to compromise on product features or performance levels in order to meet budgetary (reflected in price) or schedule (reflected in delivery) constraints. Flexibility of both supply and demand can have significant strategic and financial value if they are properly aligned. However, customers are mostly unaware of mapping of demand flexibility on to supply flexibility and its impact on production cost and time. Recent advances in information technology have made it possible to co-design a product that involves customer on one end and the manufacturer on the other. This creates an aura and an opportunity where a middle ground between the supply and demand flexibility can be explored and a “deal” can be struck where both parties settle for a product that is beneficial to both through a negotiated settlement. In this paper, we develop a framework for such negotiations. The customer requirements are treated as a range of negotiable options instead of a set of fixed inputs. Demand and supply for customization is then matched by aligning the flexibility of manufacturing systems with customers’ requirement options. Based on this framework, a negotiation scheme is developed to assist customers and manufacturers in exploring and utilizing demand and supply flexibility information in co-design. The negotiation scheme is formulated using goal programming. Finally, an interactive problem-solving procedure is developed and implemented with an illustrative example.

A network approach for modeling and design of agile supply chains using a flexibility construct

Agility can be viewed as a need to encourage the enterprise-wide integration of flexible and core competent resources so as to offer value-added product and services in a volatile competitive environment. Since flexibility is considered a property that provides change capabilities of different enterprise-wide resources and processes in time and cost dimensions, supply chain flexibility can be considered a composite state to enterprise-wide resources to meet agility needs. Enterprise modeling frameworks depicting these composite flexibility states are difficult to model because of the complex and tacit interrelationship among system parameters and also because agility thrives on many business objectives. In view of this, the modeling framework presented in this paper is based on analytical network process (ANP) since this methodology can accommodate the complex and tacit interrelationship among factors affecting enterprise agility. The modeling framework forms a three-level network with the goal of attaining agility from the perspective of market, product, and customer as the actors. The goal depends on substrategies that address the characteristics of the three actors. Each of these substrategies further depends on manufacturing, logistic, sourcing, and information technology (IT) flexibility elements of the enterprise supply chain (SC). The research highlights that, under different environmental conditions, enterprises require synergy among appropriate supply chain flexibilities for practising agility. In the present research, the ANP modeling software tool Super Decisions™ has been used for relative prioritization of the supply chain flexibilities. We demonstrate through sensitivity analysis that dynamic conditions do require adjustments in the enterprise-wide flexibility spectrum.

From mass customization to mass personalization: a strategic transformation

Business and operations strategists have long sought to formulate strategies that would serve profitably for a market of one. Two decades after its conception, there is growing evidence that mass customization strategy is transforming into a mass personalization strategy, making the market of one a reality, at least in select industries. The degree of transformation of a company depends on the extent to which its product is soft, i.e., can be produced electronically. Thus, at the lower end of the personalization spectrum are manufacturing companies engaged in producing hard, configurable products, while on the high end of the spectrum are service companies whose product can be totally configured and delivered electronically. The underlying factors that are enabling this transformation, in our view, are: (1) development of information technologies such as peer to peer (P2P), business to consumer (B2C), and Web 2.0, (2) near-universal availability of the Internet, (3) customer willingness and preparedness to be integrated into the process of product co-design and co-creation, (4) modern manufacturing systems, such as flexible manufacturing and, of course, (5) mass customization tools such as modularity and delayed differentiation, which help reduce manufacturing cost and cycle times and (6) deployment of customer-satisfaction-specific software called customer relationship management (CRM) to engender customer retention. Due to the importance and strategic success of affordable personalization, this issue is dedicated to that theme. The articles included in this issue would, I believe, serve as significant decision support mechanisms for companies pursuing a mass customization and personalization strategy. In addition to providing a brief perspective on articles included in this issue, we also summarize the state of the art of mass customization research.

The impact of operations redesign on the safety stock investment in supply chains

This study is motivated by a real problem encountered in the manufacturing and distribution process at a local electronic manufacturer of security devices. We investigate the impact of operations redesign (i.e., operations merging) on the cost of safety stock in a supply chain. A simple safety stock method is used to derive a model for estimating safety stock levels. Our result shows that operations redesign can have a significant impact on safety stock investment. We extend and complement the existing literature in the following aspects: (i) we address the issue of safety stock deployment, i.e., we not only investigate the problem of how many operations should be delayed, but also determine which operations need to be delayed, (ii) we provide an efficient heuristic algorithm to determine which operations need to be merged, and (iii) we find the optimal operations redesign strategies under some special cases. Our analysis also reveals some important conditions and insights for better operations redesign, which enable us not only to decide when an operations redesign is appropriate, but also to suggest the scale and the format of the operations redesign.

Influence of weave of carbon fabric on abrasive wear performance of polyetherimide composites

Three composites of Polyetherimide (PEI) reinforced with carbon fabric (CF) of three weaves viz. plain, twill and satin-4 H were developed keeping the amount of fabric constant (55% by vol.). Studies on mechanical properties confirmed that the twill weave composite (T) showed the highest strength, modulus (both tensile and flexural) and interlaminar shear strength (ILSS) followed by satin (S) and plain weave (P) composites. The performance order, however, was reverse in the case of toughness and elongation to break. Specific wear rate in a single-pass, unidirectional and un-lubricated abrasive wear mode against SiC paper showed strong influence of weave in mild wear condition (load 10 N). Composite S showed the highest wear resistance (W _R) followed by composites T and P. With increase in load, the difference in performance diminished to the extent that at 40 N, it was almost similar for all the three composites. This was correlated with the difference in the length of the fibers between crossover points which, in turn, allowed the microdisplacement of fibers in the composites during abrasion. This was supported by the SEM.