Paulo Peças

Influence of silicon powder-mixed dielectric on conventional electrical discharge machining

Electrical discharge machining (EDM) is a technological process with a large industrial implementation. Its use is particularly intense when very complex shapes on hard materials with a high geometrical and dimensional accuracy are required. However, the technological capability of the process has limited its application when the specification of the part surface quality imposes polished and mirror-like characteristics. The addition of powder particles in suspension in the dielectric modifies some process variables and creates the conditions to achieve a high surface quality in large areas. This paper presents a new research work aiming to study the performance improvement of conventional EDM when used with a powder-mixed dielectric. A silicon powder was used and the improvement is assessed through quality surface indicators and process time measurements, over a set of different processing areas. The results show the positive influence of the silicon powder in the reduction of the operating time, required to achieve a specific surface quality, and in the decrease of the surface roughness, allowing the generation of mirror-like surfaces.

Best practices of collaboration between university and industrial SMEs

Purpose – The purpose of this paper is to contribute to the implementation of best practices of collaboration between university and industrial small‐ and medium‐sized enterprises (SMEs).Design/methodology/approach – This paper presents the experience carried on by a university group fostering the collaboration with SME companies involving young engineering students and researchers in projects designed for the resolution of real industrial problems. A collaboration model is proposed and described. Four real case studies are presented.Findings – The purposed model promotes the involvement of the young engineers with authentic industrial experiences, enables the build‐up of their practical framework and encourages their entrepreneurial growth. It also promotes the innovation process in SME companies through the close collaboration with universities.Practical implications – The collaboration between universities and SME companies should be based on a small projects base. These projects must be focus in local...

Assessment of Energy Consumption in Injection Moulding Process

Injection moulding may appear to be a benign process regarding energy consumption. However, the large scale of this process makes its impacts especially critic and minor efficiency improvements may lead to high overall energy savings. Moreover, energy consumption affects not only the product manufacturing costs, but is also a critical component in any overall sustainability strategy. This paper presents a model that estimates in an early phase of the design of a plastic part the energy consumption during its manufacturing. This enables estimating the energy consumption for different part geometries and different machines and process conditions prior to the production phase. Moreover, this paper contributes in integrating thermodynamic fundamentals and empirical relations fostered by literature review and an experimental analysis developed in an injection moulding company. In the end the thermodynamic/empirical model is validated by comparing its results for several parts with the measured real energy consumption.

Laser welding of low-thickness zinc-coated and uncoated carbon steel sheets

Laser welding is a competitive joining process for low-thickness plates. The speeds achieved with laser welding using a CO2 laser and the low heat input introduced to the base material are the main advantages of this process. The widespread use of laser welding will increase the productivity and accuracy of welding operations. Nevertheless, there are still important developments to be made.The results of laser welding of thin sheets (below 1.25 mm) of uncoated and zinc-coated carbon steels are presented. A CO2 laser was used for the welding of sheets of different thicknesses and to make dissimilar welds (carbon steel to zinc-coated steel). The bead dimensions and the distortions of the welded sheets are analysed.

Nonconformity tracking and prioritisation matrix: an approach for selecting nonconformities as a contribution to the field of TQM

Selecting quality improvement projects among a variety of mutually competing ones is characterised by prioritisation. In practice, this is often done by the rule of thumb, following a single attribute criterion or by subjective preferences of individual stakeholders of a project team. An approach to track systematically nonconformities and to identify those critical ones that should be prioritised based on multi-attribute criteria is presented. The approach is introduced and its purpose is explained. After the background of relevant topics is given, the method’s importance in research and for practitioners is derived. Steps of the approach are portrayed and an application case of a mature industrial company, integrated in the supply-chain of the automotive industry, is presented. Elements of quality tools and techniques are used as attributes, namely failure mode and effect analysis and Pareto diagram. Results based on industrial data indicate that the use of this approach contributes to support informed and structured prioritisation decisions, which foster a more efficient improvement of future quality-based projects.

Application of Life Cycle Engineering for the Comparison of Biodegradable Polymers Injection Moulding Performance

The use of biodegradable and compostable polymers (BDP) has a rising concern derived from its particular characteristics. Currently, various BDPs are combined to improve technical performance, to open up new applications or to reduce costs. In this paper a Life-Cycle-Engineering model is developed to compare the economical, environmental and technical dimensions of performance for 4 different types of BDPs when processed through injection moulding technology. The proposed model allows for comprehensive alternative comparison, supporting informed material selection decisions in a product-design context. The use of a ternary decision space supports materials comparison and the identification of their ‘‘best alternative domains’’.

Nonconformity Root Causes Analysis Through a Pattern Identification Approach

Controlling, maintaining, and improving quality is a central topic in manufacturing. Total Quality Management (TQM) provides several tools and techniques to deal with quality related topics, which are not always applicable. With the increased use of Information Technology (IT) in manufacturing there is a higher availability of data with great potential of further improvements. At the same time this results in higher requirements for data storage and processing with demanding, time consuming sessions for interpretation. Without suitable tools and techniques knowledge remains hidden in databases. This paper presents a methodology to help analyzing root causes of nonconformities (NCs) through a pattern identification approach. Hereby a methodology of Knowledge Discovery in Databases (KDD) is adapted and used as a quality tool. As the core element of the KDD methodology, the data mining, a well-known statistical measure from the field of economics—the Herfindahl–Hirschman Index (HHI)—is integrated. After presenting the theoretical background a new methodology is proposed and validated through an application case of the automotive industry. Results are obtained and presented in the form of patterns in matrices. They suggest that concentration indices may indicate possible root causes of NCs and invite for further investigations.

Perspectives Of Mould Making Industry For Digital Global Manufacturing

In production engineering radical changes are taking place supported in new manufacturing paradigms and in technological developments. The increasing demand for meeting customer requirements and technological innovations have influenced the degree of flexibility built in the manufacturing system and its ability to respond in terms of cost, volume and time delivery. Taking the example of Portuguese mould making industry, this paper will analysed the main changes that have occurred in this industry and its ability to adapt to the availability of higher level of digital technologies and how they support new business models, extending their value adding chain.

Integration of Eco-Efficiency and Efficiency Assessment Methodologies: The Efficiency Framework

The overall aim of the Efficiency Framework is to encourage a culture of continuous improvement and sustainability within manufacturing and process industries. The framework presented supports informed decision-making processes and helps to define strategies for continuous performance improvement. The proposed innovative Efficiency Framework, materialized through the integration of concepts and results provided by eco-efficiency methodology, namely Eco-Efficiency Integrated Methodology for Production Systems (ecoPROSYS) and the lean based resource efficiency assessment method, Multi-layer Stream Mapping (MSM). Thus, the framework assesses simultaneously the environmental, economic and efficiency performance of complex production systems, which helps to identify major inefficiencies and circumstances of low eco-efficiency performance, consequently leading to the definition of improvement priorities. Ultimately, this framework aims to facilitate the overall efficiency performance assessment, by an integrated multi-dimensional analysis, presented as the Total Efficiency Index. The logic behind this index is to combine, for each unit process and for the overall production process, two fundamental efficiency aspects, namely eco-efficiency and operations efficiency.

Life Cycle Engineering Framework for Technology and Manufacturing Processes Evaluation

Nowadays, the performance of products and processes along the life cycle is a competitive issue for the industrial development as well as a permanent challenge for researchers. This paper proposes a comprehensive life cycle framework to support the selection of sustainable technology and manufacturing processes. Considering both cost and environmental dimensions, process-based models are used to feed data and structure information to assess the life cycle cost and environmental performance of alternative technological processes. This approach is extremely useful when dealing with decision making processes inherent to products development and to the selection of materials and/or technologies in early design stages. In parallel, a technical evaluation of candidate alternatives is also proposed. Based on cost, environmental and technical dimensions, two integrating analyses are proposed to support informed decisions by mapping the best alternatives. This framework is applied to a case study regarding alternative mould designs to produce a part through injection moulding.