Domenico Falcone

Validation and application of a reliability allocation technique (Advanced Integrated Factors Method) to an industrial system

The proposed work analyses and applies a new reliability and redundancy allocation procedure. Starting from a similar methodology previously developed by the authors, Integrated Factors Method (IFM), a new reliability allocation and optimization method is developed: Advanced Integrated Factors Method (AIFM). The new technique has been proposed to analyze complex systems in the pre-design phase, even if its general characteristics allow extending the method to different design and production phases. The previous method has been improved through the introduction of new indexes that help improve underperforming components in order to achieve the allocated reliability values. The method introduces a big number of factors, so it can be applied to a wide range of systems. It is characterized by a very simple mathematical formulation, that can be made more complicated for a more detailed analysis.

Inventory management using both quantitative and qualitative criteria in manufacturing system

Abstract The success parameters for any company are on time completion, within specific budget and with requisite performance. In particular an efficient and effective inventory management helps a firm maintaining competitive advantage, especially in a time of accelerating globalization. From this point of view several organizations employ the ABC analysis to have an efficient control on a large number of inventory items. With the increasing levels of integration in manufacturing and service systems conventional ABC analysis is limited because it accounts for only one criterion, mostly “annual dollar usage”, for classifying inventory items. To alleviate this shortcoming, this paper proposes a modified version of ABC analysis and Cross Analysis based on Analytic Network Process, a multicriteria approach, that allows to consider several criteria all at once for the optimal choice of materials management.

Study and modelling of very flexible lines through simulation

The present paper proposes the development of a virtual model simulating an assembly line. Starting from the analysis of the real line, through an incremental approach, a simulation model is created, verified and validated, in order to obtain useful information about: • productive capacity; • partial and total lead time; • Percentage of saturation, Value Added (VA) and Non-Value Added (NVA), for each worker and station. During the development phase, an important goal has been pursued: the possibility to use and change the model without knowing the creation logic. It is possible to change input parameters through simple tables, which contain times of man-machine operations. You can easily set times in order to move an operation from one station to another or to add/delete a job in a station, according to the technological and ergonomic constraints of the process. Moreover, the acquisition of scheduling data is extremely easy and starts from the generation of a list of production codes related to different work-cycles.

AHP-IFM Target: An Innovative Method to Define Reliability Target in an Aerospace Prototype Based on Analytic Hierarchy Process

Reliability target definition is a crucial aspect of any reliability analysis. In literature, there are two types of analysis. The first one, called ‘bottom-up’, goes back to the systems target using data of units through a fault tree analysis. Reliability data of components could be only partially available, particularly in the case of innovative systems. In the second type of analysis, called ‘top-down’, starting from similar systems, the target of each unit is defined, by applying allocation techniques. Also, in this case, reliability data of similar systems might not be available, and the choice of the most appropriate technique could be tricky. The purpose of the present research is to combine the advantages of both usual approaches. The newly developed approach is based on the integrated factors method, whose values are adjusted trough a multicriteria method, the analytic hierarchy process, depending on the importance of each factor and each unit. The innovation of the proposed model consists in its dynamism, as most of the literature methods use constant weights for the factors involved in reliability allocation. No method takes into account the assignment of a different level of significance (weight) to different units of the system, simultaneously with the considered factors. The developed approach has been applied on an aerospace prototype system. The results show the goodness of the new method and its ability to overcome the problems noted in literature. Copyright

Maintenance strategy design in a sintering plant based on a multicriteria approach

Maintenance strategy design greatly contributes to ensure the pre-established production capacity of an industrial system and to reduce organisation cost, without compromising customer satisfaction resulting in loss of market share. The focus of the present research is a new model for maintenance policy developed and implemented in a case study. The new approach is focused on the adequate distribution of maintenance budget to system units according to the main factors determining availability and maintenance of equipment. These factors are summarised through appropriate indices, adjusted through a multicriteria method, the analytic hierarchy process (AHP), depending on the importance level of each considered factor and unit of the system. The results can be used as a support for allocation of budgets to maintenance activities, identifying machines or units that are strategic to ensure production. The model has been applied on a real industrial plant.

A Hybrid Probabilistic Model for Evaluating and Simulating Human Error in Industrial Emergency Conditions (HEIE)

Over the years, many techniques have been developed for human reliability analysis (HRA). The main weakness of traditional HRA approaches is the use of a simple classification scheme without a link to a model of cognition in terms of mental processes. The present work is an attempt in this direction through a particular hybrid probabilistic model. The human error in industrial emergency model aims to develop an integrated methodological approach useful in critical infrastructures during an emergency condition. The proposed method, starting from the integration of existing techniques, develops a very flexible tool, able to take into account the main external and internal factors responsible of human error in emergency conditions. The model is able to estimate the evolution of human behavior and error following the evolution of the emergency scenario. The final result is a simulation model that calculates the contextualized human error probability, through which it is possible to estimate a realistic and detailed scenario of the conditions during the emergency management.

Assembly line balancing, proposal of a new methodology: integrated balancing method

In industrial plants, line balancing problems do not often find an objective solution and production managers often allocate tasks to operators without following a real methodology, but basing on personal experience; therefore, there are many problems when quick changes of capacity or constraints occur. The starting point of this study is the investigation of the main balancing methodologies, understanding their advantages and disadvantages in assigning homogenously tasks to workers. We propose new assembly lines balancing technique simple, general and effective, able to solve some ambiguity in balancing. Thanks to the proposed research, integration and a progress of classic methodologies have been realised. The method proposed, called IBM - integrated balancing method, has been applied to a real case study (the assembly line of a multinational company), in order to show its capacity of supporting production managers in designing and optimising assembly lines (ALBPs).

A New Method for Reliability Allocation: Critical Flow Method

A complex system consists of many subsystems, which are developed concurrently and sometimes independently. It would be too late to validate the system reliability until the final system prototype is ready after months or years of development. From a project management point of view, the reliability of each subsystem or sub-function should be examined as early as possible. Therefore, the allocation of a reasonable reliability requirement to each subsystem and sub-function based on the system reliability target is very important. The present work analyses, in literature, the main reliability allocation techniques. Starting from the known methodologies, a new critical flow method for reliability allocation method has been developed. The proposed method can be used for complex system with serial and parallel configurations.

A Weighing Algorithm for Checking Missing Components in a Pharmaceutical Line

To meet the requirements and specifications coming from the surrounding society, the socio-economic progress involves the development of new products, new technologies, new organizational forms etc. Companies are constantly looking for methods or procedures to improve production and income; but, the enterprise growth is strictly linked to the reliability of its internal processes. Internal failures can often cause loss of image. The goal of the present work is the development of an algorithm able to optimize the production line of a pharmaceutical firm. In particular, the proposed weighing procedure allows both checking missing components in packaging and minimizing false rejects of packages by dynamic scales. The main problem is the presence at the same time, in the same package, of different components with different variable weights. The consequence is uncertainty in recognizing the absence of one or more components.

Mathematical Models for Reliability Allocation and Optimization for Complex Systems

RAMS is an acronym for Reliability, Availability, Maintainability and Safety. These four properties concern the application of important methodologies for designing and managing complex technical systems. The present chapter analyses several reliability allocation techniques present in literature. Starting from well-known methodologies, two reliability allocation methods has been proposed and validated: Integrated Factors Method (I.F.M.) and Critical Flow Method (C.F.M.). We focus on the most important conventional methods to discuss their limitations to motivate the current research.