https://escholarship.org/content/qt4h56k1ch/qt4h56k1ch.pdf

Advanced monitoring of machining operations

Titanium and nickel alloys represent a significant metal portion of the aircraft structural and engine components. When these critical structural components in aerospace industry are manufactured with the objective to reach high reliability levels, surface integrity is one of the most relevant parameters used for evaluating the quality of finish machined surfaces. The residual stresses and surface alteration (white etch layer and depth of work hardening) induced by machining of titanium alloys and nickel-based alloys are very critical due to safety and sustainability concerns. This review paper provides an overview of machining induced surface integrity in titanium and nickel alloys. There are many different types of surface integrity problems reported in literature, and among these, residual stresses, white layer and work hardening layers, as well as microstructural alterations can be studied in order to improve surface qualities of end products. Many parameters affect the surface quality of workpieces, and cutting speed, feed rate, depth of cut, tool geometry and preparation, tool wear, and workpiece properties are among the most important ones worth to investigate. Experimental and empirical studies as well as analytical and Finite Element modeling based approaches are offered in order to better understand machining induced surface integrity. In the current state-of-the-art however, a comprehensive and systematic modeling approach based on the process physics and applicable to the industrial processes is still missing. It is concluded that further modeling studies are needed to create predictive physics-based models that is in good agreement with reliable experiments, while explaining the effects of many parameters, for machining of titanium alloys and nickel-based alloys.

Machining induced surface integrity in titanium and nickel alloys: A review

An overview of the machinability of aeroengine alloys

Achieving sustainability in manufacturing requires a holistic view spanning not just the product, and the manufacturing processes involved in its fabrication, but also the entire supply chain, including the manufacturing systems across multiple product life-cycles. This requires improved models, metrics for sustainability evaluation, and optimization techniques at the product, process, and system levels. This paper presents an overview of recent trends and new concepts in the development of sustainable products, processes and systems. In particular, recent trends in developing improved sustainability scoring methods for products and processes, and predictive models and optimization techniques for sustainable manufacturing processes, focusing on dry, near-dry and cryogenic machining as examples, are presented.

Sustainable manufacturing: Modeling and optimization challenges at the product, process and system levels

Surface integrity in material removal processes: Recent advances

A Strategy for the Compensation of Errors in Five-Axis Machining

Metal additive manufacturing has employed several technologies and processes to advance from rapid prototyping to rapid manufacturing. Additive manufacturing technologies compete with traditional manufacturing methods through their ability to produce complex structures and customized products. This paper aims to study the characteristics of stainless steel 316L (UNS S31603) parts produced using a selective laser melting machine. In the aerospace industry, turbine blades are typically manufactured from nickel-based alloys, titanium alloys, and stainless steels. Several geometries typical of airfoil blades were examined. The main goal is to investigate the material characteristics and surface features of the airfoil blades. The study included the geometrical errors, surface microstructures, material compositions, material phases, and residual stresses of the samples produced. The characteristics of the parts produced were investigated based on experimental observations. The paper also discusses the influence of the part dimension and orientation on the profile error, surface microstructure, and residual stress.

On the characterization of stainless steel 316L parts produced by selective laser melting

Selective laser melting of hybrid ex-situ/in-situ reinforced titanium matrix composites: Laser/powder interaction, reinforcement formation mechanism, and non-equilibrium microstructural evolutions

Surface microdefects such as dimples are always found on machined 1045 steel surfaces as a result of the dual phase microstructure of the workpiece material. Finite element (FE) analysis on dimple and chip formation showed similar trends to those acquired experimentally. The formation of dimples at grain boundaries is explained by considering the plastic dissipation energy inside of individual grains in the material microstructure during microscale cutting. Dimples are shown to occur at a hard-soft grain boundary in the direction of cutting, but never at a soft-hard grain boundary.

Surface defects during microcutting

This paper investigates critical issues related to high-speed five-axis milling of hardened D2 tool steel (hardness HRc 63). A forging die cavity was designed to represent the typical features in dies and molds and to simulate several effects resulting from complex tool path generation. Cutting tool materials used were coated carbide for the roughing and semi-finishing processes and polycrystalline cubic boron nitride (PCBN) for the finishing process. The effects of complex tool paths on several critical machining issues such as chip morphology, cutting forces, tool wear mechanisms, tool life and surface integrity were also investigated. The main tool failure mode was chipping due to the machine tool dynamics. A five-axis analytical force model that includes the cutter location (CL) data file for computing the chip load has been developed. The effect of instantaneous tilt angle variation on the forces was also included. Verification of the force model has been performed and adopted as a basis for explaining the difficulties involved with high-speed five-axis milling of D2 tool steel.

Mohamed Elbestawi

Papers

A Strategy for the Compensation of Errors in Five-Axis Machining

On the characterization of stainless steel 316L parts produced by selective laser melting

Selective laser melting of hybrid ex-situ/in-situ reinforced titanium matrix composites: Laser/powder interaction, reinforcement formation mechanism, and non-equilibrium microstructural evolutions

Surface defects during microcutting

High-speed five-axis milling of hardened tool steel