Evaluation of Cooling Potential and Tool Life in Turning Using Metalworking Fluids Delivered in Supercritical Carbon Dioxide

Carbon Dioxide is an industrial byproduct that has been proposed as an alternative metalworking fluid (MWF) carrier with lower environmental impacts and better cooling potential than existing MWFs. This paper investigates the heat removal and tool life effects of rapidly expanding supercritical CO2 (scCO2)-based MWFs relative to MWFs delivered as a flood of semi-synthetic emulsion or as minimum quantity lubrication (MQL) sprays. When cutting both compacted graphite iron (CGI) and titanium, tool wear was most effectively controlled using the scCO2-based MWF compared with the other MWFs. Analysis in this paper suggests that the performance benefit imparted by rapidly expanding scCO2 appears to be related to both the cooling potential and penetration of the sprays into the cutting zone. High-pressure gas sprays have lower viscosity and higher velocity than conventional MWFs. An experiment in which the spray direction was varied clearly demonstrated the importance of spray penetration in tool wear suppression. The type of gas spray is also a significant factor in tool wear suppression. For instance, a spray of N2 delivered under similar conditions to CO2 effectively reduced tool wear relative to water based fluids, but not as much as CO2. This result is particularly relevant for MQL sprays which are shown to not cool nearly as effectively as scCO2 MWFs. These results inform development of scCO2-based MWFs in other machining operations, and provide insight into the optimization of scCO2 MWF delivery.

Numerical Simulation on Nanoparticles Integrated Laser Shock Peening of Aluminum Alloy

In this paper, numerical simulation of nanoparticle integrated laser shock peening of aluminum alloys was carried out. A “tied constraint” was used to connect the matrix and nanoparticle assembly in ABAQUS package. Different particle size and particle volumes fraction (PVF) were studied. It was found that there is significant stress concentration around the nanoparticles. The existence of nanoparticle will influence the stress wave propagation and thus the final stress and strain state of the material after LSP. In addition, particle size, PVF and particle orientation all influence the strain rate, static residual stress, static plastic strain and energy absorption during the LSP process.

A Volume-of-Fluid Based Numerical Simulation of Solidification in Binary Alloys on Fixed Non-Uniform Co-Located Grids

In this paper, the authors present a platform for the modeling of mold filling and solidification of binary alloys with properties similar to Mg alloys. A volume-of-fluid (VOF) based method is used to capture the interface between solid and liquid in binary alloys solidification process on a fixed non-uniform grid, developed for implementation in a colocated finite volume framework. Contrary to other works, to update the volume fraction (of fluid) in the field, a link between source-based type of energy equation and VOF reconstruction algorithm is described and implemented. A new approximation to the pressure gradient is presented to remove all ‘Spurious Currents’ [1] resulting from pressure jumps in the vicinity of the interface. Based upon the work presented, it is concluded that the present combination of the equations are not only computationally straightforward to implement and upgrade to a 3D problem, but also provides an excellent platform to capture the interface between constituents in a die-casting process including solidification and mold filling process. The current framework will be used in future works to characterize the local mechanical properties of Mg alloys by using information from simulation at the dendritic level.

Noise Reduction During Acoustic Monitoring of Laser Welding of High-Strength Steels

During the laser welding process of high-strength steels, different defects, such as a partial weld penetration, spatters, and blow-through holes could be present. In order to detect the presence of defects and achieve a quality control, acoustic monitoring based on microphones is applied to the welding process. As an effective sensor to monitor the laser welding process, however, the microphone is greatly limited by intensive noise existing in the complex industrial environment. In this paper, in order to acquire a clean acoustic signal from the laser welding process, two noise reduction methods are proposed: one is the spectral subtraction method based on one microphone and the other one is the beamforming based on a microphone array. By applying these two noise reduction methods, the quality of the acoustic signal is enhanced, and the acoustic signatures are extracted both in the time domain and frequency domain. The analysis results show that the extracted acoustic signatures can well indicate the different weld penetration states and they can also be used to study the internal mechanisms of the laser-material interaction.

An Overview of Possible Integration of Green Design Principles Into Mechatronic Product Development Through Product Lifecycle Management

People that work on the development of mechatronic products do not have enough data related to the end of the product lifecycle when making decisions related to the product design. Sustainable design tools in Product Lifecycle Management (PLM) systems could enable more sustainable designs with ‘greener’ decision-making. PLM tools, which are supporting designs of mechatronic products, are lacking more consideration about the product’s overall lifecycle ecological footprint. Most decisions that are made during the design phase are based on costs of materials and processes that are involved in development and manufacturing, not to the service, reuse, recycling and disposal of such products. This study will investigate the possibility of including the data related to the end of the product lifecycle. Integrating green design tools into the PLM systems would help mechatronic engineers to develop more sustainable designs. This paper will investigate the current state of the art in the area of Product Lifecycle Management systems that support design and realization of mechatronic projects. It discusses some ideas that can be used for determining a framework for data capturing of electro-mechanical product related data. This would connect decisions in earlier phases with the ones in final stages of a product lifecycle. This data can be used for the environmental footprint determination.

Modeling and Simulation of Process and Structure Interactions Considering Turning Operations

A consideration of the dynamic interaction between the machine tool structure and the cutting process is required for the prediction and optimization of machining tasks through simulation. This paper outlines a modular, analytical cutting force model applicable to common turning processes. It takes into account the dynamic material behavior and nonlinear friction ratios on the rake face as well as heat transfer phenomena in the deformation zones. In order to overcome simplifying assumptions in analytical cutting force descriptions and to incorporate the chip formation process into the analysis, specific input variables are determined in a metal cutting simulation based on the Finite Element Method (FEM). On the machine tool structure side, the setup of a parametric FEM model is presented. The accuracy of both the machine tool and cutting force models was verified experimentally on a turning center.

Developing a Durability by Design Process

Modern fatigue analysis is providing analytical solutions to problems that could previously be addressed only by methods that were highly empirical and often inaccurate. We can now focus on five crucial steps to successful fatigue analysis. Working from elastic finite element models, the five steps are: 1) the calculation of elastic-plastic stresses and strains for complex loading and biaxial stress states; 2) modification of the endurance limit to allow for the interaction between small and larger cycles; 3) the calculation of the life to crack initiation; 4) critical plane searching to determine the orientation of a potential crack; 5) and an assessment of whether the crack will propagate to failure. The paper describes these steps and the underlying theories, and gives industrial examples of their application to real components.

Effects of Chip Seizure on Steady State Motion of a Machine-Tool

The steady state motion of a machine-tool is numerically predicted with interaction of the chip/tool friction boundary. The chip/tool friction boundary is modeled via a discontinuous systems theory in effort to validate the passage of motion through such a boundary. The mechanical analogy of the machine-tool is shown and the continuous systems of such a model are governed by a linear two degree of freedom set of differential equations. The domains describing the span of the continuous systems are defined such that the discontinuous systems theory can be applied to this machine-tool analogy. Specifically, the numerical prediction of eccentricity amplitude and frequency attribute the chip seizure motion to the onset or route to unstable interrupted cutting.

An Surplus Asset Management Model for Environmental Impact Analysis of EOL Electronic Products

With increasing environmental regulations and waste management costs, environmentally conscious design and manufacturing (ECDM) and surplus asset recovery are becoming a more attractive approach to solve environmental problems. Any company that owns a collection of PCs, printers and other electronic accessories probably needs to manage these assets more effectively, but currently there is a lack of tools for effective management. Therefore, this paper discusses, from the viewpoint of an enterprise dealing with end-of-life electronic products, the recycling processes according to literature, and derives an integrated model on surplus asset management and environmental impact analysis. The primary objective of the model is to develop a certain tool for managing surplus asset within a corporate office and generate a decision making tool for those who are concerned with the environmental issues in the design or recycling phase. Based on this model, a prototype system is introduced in detail in this paper.

Experimental Study on the Mechanical Property and Forming Limit of Magnesium Sheet at Elevated Temperatures

Magnesium alloy sheet has received increasing attention in automotive and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. Most of work in the field has been working with the magnesium sheet after annealed around 350°C. In this paper, the as-received commercial magnesium sheet (AZ31B-H24) with thickness of 2mm has been experimentally studied without any special heat treatment. Uniaxial tensile tests at room temperature and elevated temperature were first conducted to have a better understanding of the material properties of magnesium sheet (AZ31B-H24). Then, limit dome height (LDH) tests were conducted to capture forming limits of magnesium sheet (AZ31B-H24) at elevated temperatures. An optical method has been introduced to obtain the stress-strain curve at elevated temperatures. Experimental results of the LDH tests were presented.