N. Ortega

Computer simulation of performance of electrical discharge machining operations

The electrical discharge machining (EDM) process is optimum for accurate machining of complex geometries in hard materials, as those required in the tooling industry. It has become by far the most popular among the non-conventional machining processes. However, although a large number of EDM machines are sold every year, available knowledge of the process is still very empirical. Experimental trials are required in many cases to set up the optimum conditions for an EDM operation, resulting in increases in lead-time and cost for the final part. The reason for this is the complex nature of the process, highly stochastic, that involves simultaneous interaction of thermal, mechanical, chemical and electrical phenomena. Therefore, research efforts must be directed towards process modelling in order to reduce the experimental cost associated to the technology. In this work, an original computer simulation model of the EDM process is presented. The model is based on the numerical calculation of temperature fields within the workpiece, from which the amount of part material removed per discharge can be estimated. The objective is to theoretically predict material removal rate (MRR) and the final surface finish of the machined part using as input variables the EDM process parameters and the properties of the work material. The model has been validated by carrying out tests on an industrial EDM machine, showing that it can adequately predict MRR and surface roughness with errors below 9%.

Analysis of Micro-Pin Manufacturing Using Inverse Slab Electrical Discharge Milling (ISEDM) Process

Abstract. This paper analyses the technological capabilities of a novel rotary (EDM) electrical discharge machining process for the manufacturing of high aspect ratio cylindrical micro-components. The process is called Inverse Electrical Discharge Grinding (ISEDM). An experimental analysis has been carried out on high speed steel (tool steel Vanadis 23), using a conventional EDM machine and graphite electrode. The effect of pulse off-time, work piece final diameter and machining length on material removal rate, electrode wear ratio, radial accuracy and surface roughness has been quantified. From the study, optimum strategies that involve the use of different EDM regimes for achieving the optimum requirements can be defined. Micro-pins of 0.3 mm diameter with aspect ratio as high as 100:1 have been successfully manufactured.

A computer assistant for monitoring tool performance during the drilling process

Nowadays, making holes using the drilling process plays a fundamental role in the manufacturing industry. However, preventing tool wear and/or breakage is still a major concern. From the production process point of view, several undesirable consequences may arise, such as downtimes, increased production costs, loss of dimensional tolerances and even irreversible workpiece defects. In this sense, the present article presents a computer assistant, which provides information about the current drilling process system. In particular, the computer assistant detects both tool wear and material heterogeneities.

Wire Electrical Discharge Machines

Amongst the non-conventional machining processes, electrical discharge machining has no doubt gained a deserved reputation and popularity in the second half of the 20th century. Wire electrical discharge machines appeared some 30 years ago, and since then the development of new applications in the field of very hard material precision machining, and consequently, the market share of technology is growing continuously. In this chapter the main aspects related to the technology and equipment for wire electrical discharge machining are addressed: the first research that led to the process as it is known today, machine components and intelligence, industrial and academic research and the latest advances in the field of thin-wire EDM are discussed in the following sections.

Characterization of the Response of Embedded Thermocouples in Grinding

Temperature measurement in grinding has been a widely analyzed field in the study of the process. Temperatures in grinding are too difficult to measure due to the high gradients in the ground workpiece. A lot of different methods have been employed by many researches in the last years. In this paper the use of thermocouples is analyzed attending to the mathematical characterization of their response. It will be shown that correct modeling of the thermocouple’s response permits the avoidance of the problem of thermal inertia, making thus possible the use commercial thermocouples for temperature measurement in grinding.

Industrial Application of the MCG (Minimum Coolant Grinding) Technology

The use of fluids in grinding is necessary to carry out an optimized process that avoids any kind of damage in the ground workpieces. However, the use of fluids in machining processes presents some problems as the economic one and the environmental one. The present work analyzes the industrial viability of a new solution to avoid the use of fluids in grinding, the MCG system. This system combines the use of a MQL (Minimum Quantity Lubricant) commercial system and a gas supplied at low temperatures. In this case the grinding of a component of the engine of a competition motorcycle with the MCG (Minimum Coolant Grinding) system is compared with the classic fluid flow system.

Implementation of Simulation Software for Better Understanding of Manufacturing Processes

The adaptation of universities to the European Higher Education Area (EHEA) plays an essential role in society, creating new knowledge, transferring it to students by means of new and more active methodologies aimed at learning that will enable students to put everything they learn into practice. However, such methodologies are not equally applicable in all subjects. Subjects such as Manufacturing Technology, taught at different levels in both undergraduate and graduate levels, are descriptive to a great extent. This descriptive nature must be supported by new technologies if these subjects claim to be more attractive to students. In this paper some examples of successful case studies are presented. They represent the new way of understanding the teaching replacing the old concept of traditional classroom lecture by more interactive ones and, therefore, more attractive to students.

Electrodischarge dressing (EDD) applied to contour grinding

Superabrasive grinding is a high efficiency process used in special applications such as high speed grinding, creep feed grinding, and Quick-Point. Although the maximum efficiency is obtained by metallic bonded wheels due to their wear resistance, their hardness makes almost impossible to dress them properly. Vitrified bonded wheels are now being used instead of metallic bonded ones since they have superior self-dressing capability. With the aim of obtaining maximum efficiency of these special grinding processes, in the last years a number of non-conventional dressing processes have been developed allowing the use of metallic bonded wheels. In this work, a methodology to introduce the electro-discharge dressing (EDD) of superabrasive conductive metallic bonded wheels is presented. The efficiency of EDD process to regenerate shaped wheels applied in Quick-Point or peel grinding has been studied by grinding hard metal rollers. Results show that EDD is able to remove the run-out and regenerate cutting capability.

Aeronautics Advanced Manufacturing Center, the Bet to Surpass the Valley of Death between University and Company

The present times are changing and need new formulas that satisfy the need for effective transfer between universities and companies. In the Basque Country, attending to this demand the Aeronautics Advanced Manufacturing Center (CFAA) has been founded. This center belongs to the University of the Basque Country (UPV/EHU) and has several companies related to this strategic sector as partners. The CFAA, equipped with the latest machinery and technology, born to be a catalyst for research activity in the field of advanced manufacturing for aeronautical sector, focusing its activity on the called Pillar 2 of the MRL scale (Manufacturing Readiness Level) as the proximity to the final application. Belonging to the UPV/EHU, this center allows stays of doctoral students, students for performing their master and bachelor’s degree projects. This implies a high quality training, and closer to reality, in manufacturing technologies.

New Technologies for Increasing the Capacities of WEDM Machines

The process of Wire Electrical Discharge Machining (WEDM) has experienced a dramatic growth in the last years. Together with the new requirements imposed by customer needs, globalization of the markets has brought about a new scenario in which competitiveness is the keyword. In the case of WEDM, it is only possible from a perspective that integrates developments in hardware, software and know-how, to generate the required added-value with respect to competitors. For instance, it is not enough to give an answer to the demand of a high-speed first cut: economy must be achieved together with a high accuracy and using low-cost wires. In this paper the research actions currently running aiming at the development of a new generation of WEDM machines are presented. The objective of this paper is to present an integrated research approach focused on industrial needs, covering the following aspects: Accuracy and productivity; automation and machine intelligence; eco-efficiency.