Mihai Nicolescu

Influence of Tool Materials on Machinability of Titanium- and Nickel-Based Alloys: A Review

Titanium and nickel alloys are the most commonly used in the demanding industries like aerospace, energy, petrochemical, and biomedical. These highly engineered alloys offer unique combination of heat resistance, corrosion resistance, toughness, high operating temperature, and strength-to-weight ratio. These alloys are termed as “Difficult to cut materials” because of their low machinability rating. They are difficult to machine because of properties like low thermal conductivity, high strength at elevated temperatures, and high chemical reactivity. Machining of titanium- and nickel-based alloys causes problems of surface integrity and selection of cutting tool materials that is always a challenge for manufacturers. In this work, machinability studies for titanium and nickel alloys are reviewed with reference to cutting tool materials, associated wear mechanisms, failure modes, and novel tooling techniques. It also discusses major surface integrity defects like carbide cracking, white layer formation, work hardening layer formation, residual stresses, and microstructural alterations. Major aim of this work is to evaluate the challenges involved in improving machinability of the titanium- and nickel-based alloys, and determine the future research direction for productivity improvements in machining these alloys.

Minimal quantity cooling lubrication in turning of Ti6Al4V : Influence on surface roughness, cutting force and tool wear

Titanium alloys generally show low machinability ratings. They are referred as difficult-to-cut materials due to their inherent properties such as low thermal conductivity, high chemical reactivity and high strength at elevated temperatures. Cooling strategies play an important role to improve the machining performance of the cutting process. In order to facilitate the heat dissipation from the cutting zone, generous amount of coolant is used when machining highly reactive metals such as titanium alloys. Generally, cutting coolants are nominated as pollutants due to their non-biodegradable nature. This article presents experimental evaluation of a minimal quantity cooling lubrication system. The study investigates a combination of sub-zero-temperature air and vegetable oil–based mist as possible environmentally benign alternative to conventional cooling methods. The results are compared with the dry and flood cutting environments as well. Machinability was evaluated experimentally by considering the surface finish, cutting forces, tool life and their associated tool wear mechanisms. It was concluded from the results obtained from the surface roughness, cutting force and tool life investigation that minimal quantity cooling lubrication (internal) cooling strategy has encouraging potential to replace the conventional flood cooling method.

Prediction of energy consumption and environmental implications for turning operation using finite element analysis

This article is concerned with the experimental and numerical investigation of energy consumption involved in the turning of Ti6Al4V titanium alloys. Energy consumption of a machining process is considered as an important machining performance indicator. This article aims to propose an approach for the prediction of energy consumption and related environmental implications using finite element modeling simulations. Machining experiments were conducted using uncoated carbide tools under dry cutting environment. DEFORM-3D software package was utilized to simulate finite element–based machining simulations. Experimental validation was mainly conducted by focusing on the cutting forces and power consumption measurements. Simulated results of the cutting force and power consumption were found in a good agreement with the experimental findings. The amount of CO2 emission resulting from energy consumption during the machining phase is highly dependent on the geographical location. This study also incorporated the energy mix of United Arab Emirates for the environmental calculations. Finally, in the light of proposed methodology, possible future directions and recommendations have also been presented.

An experimental analysis of energy consumption in milling strategies

Pocket milling operation is one of the widely used milling operations. CAM packages offer different tool path strategies to execute a machining operation. In the presented work zigzag, constant overlap spiral, parallel spiral and oneway tool path strategies were compared in terms of power and energy consumption for pocket milling of Al 6061 aluminum alloy. All pocketing operations were conducted using 8 mm diameter High Speed Steel (HSS) end milling cutters. Energy utilization was analysed for all tool path strategies. This work aims to develop better understanding towards sustainability concept in core machining phase.

Particularities of Grinding High Speed Steel Punching Tools

A simulation model of a punch grinding process has been used to determine optimal parameters to reduce grinding cycle time and achieve a constant-temperature no-burn situation. Two basic outputs of the simulation model include arc length of contact and specific material removal rate that are both time-variant. A thermal model is included in the simulation to calculate maximum grinding temperature rise. The simulation-based optimization can help to avoid thermal damage, which includes thermal softening, residual tensile stress, and rehardening burn. The grindability of high speed steel (HSS) is presented in terms of specific grinding energy versus undeformed chip thickness and maximum temperature rise versus specific material removal rate. It is shown that for a given specific material removal rate lower temperatures are achieved when grinding fast and shallow. Higher temperatures, characteristic for slow and deep grinding, soften the material leading to a lower specific grinding energy, especially if grinding is timid. Lowest values of specific grinding energy can be achieved in fast and shallow grinding at aggressive grinding conditions.

Stochastic Modelling and Online Adaptive Control of Cutting Forces in Turning

Summary This paper presents the development of a new parameter-adaptive control system for on-line cutting force control in turning. The control system adjusts the feedrate in-process in order to compensate for the varying machinability of the cutting process. Since the machining system—consisting of the cutting process and the machine tool structure — is a system with time-variable dynamics, it is necessary for the control system also to identify the process parameters and adapt the regulator correspondingly in real-time in order to avoid instability problems. The system presented in this paper is based upon stochastic modeling, recursive identification and pole-assignment design. The paper includes a theoretical analysis, and the applicability of the system is demonstrated by experimental test results.

A new approach in standardising a European curriculum in production engineering

The need for a flexible and versatile workforce that is constantly learning and upgrading its skills has led to a continual demand for courses in which employees are re-trained and updated on a lifelong basis. Students and workers now have to be prepared for a labour market in which they can be expected to change jobs many times, and they need to acquire appropriate skills that are transferable and portable across sectors, countries and cultures. This paper presents a new approach to unifying a European curriculum for production engineering. The paper discusses the background, developments, module structure, testing and ongoing work that is carried out in the European Production Engineering Certification project – a two year pilot project granted by the European Union Programme Leonardo da Vinci.

Influence of rake angle on the cutting energy when modeling the machining of Ti6Al4V

The finite element based machining simulations have been used widely in industry and academia to analyze the machining process. These virtual machining simulations have advantages over the real machining experiments due to the immense potential of saving time and expenses. The simulation techniques are even more popular when machining difficult to cut materials such as titanium alloy (Ti6Al4V). In order to make machining process sustainable in nature, energy consumption during the cutting process should be optimized accordingly. The present study aims to provide an insight towards the relation of cutting energy with respect to the different cutting tool geometries. The study used finite element based simulations to investigate the effect of rake angle on the cutting energy. Based on the cutting energy outcomes different suggestions were made to minimize the cutting energy.

Virtual Machining System Engine for Simulation of Process Machine Interaction

The aim of this paper is to introduce a novel methodology, based on a finite element (FE) computation engine for simulation of process machine interaction occurring in machining systems. FE modelli ...

Sensors' network and its application in the intelligent storage security

Intelligent storage systems run on different advanced technologies, such as linear layout, business intelligence and data mining. Security, the basic desire of the storage system, has been focused on with the indraught of multimedia communication technology and sensors’ network. Along with the developing of science and the social demands, multifarious alarming system has been designed and improved to be intelligentized, modularized and have network connections. It is of great moment to make the storage, and further more, the logistics system more and more efficient and perfect with modern science and technology. Diversified information on the spot should be caught by different kinds of sensors. Those signals are treated and communicated to the control center to give the further actions. For fire-proofing, broad-spectrum gas sensors, fume sensors, flame sensors and temperature sensors are used to catch the information in their own ways. Once the fire is taken somewhere, the sensors work by the fume, temperature, and flame as well as gas immediately. Meanwhile the intelligent control system starts. It passes the tidings to the center unit. At the same time, it sets those movable walls on to work quickly to obstruct the fire’s spreading. While for guarding the warehouse against theft, cut-off sensors, body sensors, photoelectric sensors, microwave sensors and closed-circuit television as well as electronic clocks are available to monitor the warehouse reasonably. All of those sensors work in a net way. The intelligent control system is made with a digital circuit instead of traditional switch one. This system can work in a better way in many cases. Its reliability is high and the cost is low.