Near net shape manufacturing of metal: A review of approaches and their evolutions

Abstract

In the last thirty years the concept of manufacturability has been applied to many different processes in numerous industries. This has resulted in the emergence of several different "Design for Manufacturing" methodologies which have in common the aim of reducing productions costs through the application of general manufacturing rules. Near net shape technologies have expanded these concepts, targeting mainly primary shaping process, such as casting or forging. The desired outcomes of manufacturability analysis for near-net-shape (NNS) processes are cost and lead/time reduction through minimization of process steps (in particular cutting and finishing operations) and raw material saving. Product quality improvement, variability reduction and component design functionality enhancement are also achievable through NNS optimization. Process parameters, product design and material selection are the changing variables in a manufacturing chain that interact in complex, non-linear ways. Consequently modeling and simulation play important roles in the investigation of alternative approaches. However defining the manufacturing capability of different processes is also a "moving target" because the various NNS technologies are constantly improving and evolving so there is challenge in accurately reflecting their requirements and capabilities. In the last decade, for example, CAD, CNC technologies and innovation in materials have impacted enormously on the development of NNS technologies. This paper reviews the different methods reported for NNS manufacturability assessment and examines how they can make an impact on cost, quality and process variability in the context of a specific production volume. The discussion identifies a lack of structured approaches, poor connection with process optimization methodologies and a lack of empirical models as gaps in the reported approaches.

Development of constitutive equations for hot working of titanium matrix composites

“…According to previous research, globularisa on of secondary lamellar alpha induced by beta strain [4,5,12] , dynamic recrystalliza on [8] , breaking and debonding of ceramic reinforcements [4,5] , have been observed and revealed regarding to dual phase tanium matrix composites at hot working condi on. There are other mechanisms, such as adiaba c hea ng [12] and rota on of whisker reinforcements [13] .…”

“…Accordingly, the processing window was defined, and the hot working methods, such as isothermal forging, hot extrusion and rolling process have also been employed to improve the microstructure and achieve sheet or bulking materials. [6,7] Near net shape forming methods have great advantages of material u lising rate and excellent materials proper es [8] . However, few research has been devoted to inves gated near net shape forming methods of TMCs.…”

Process selection methodology for near net shape manufacturing

“…Near net shape is a relative property, rather than absolute, that defines a combination of product geometry (to be produced), material and manufacturing process (primary shaping process) to be minimal in raw material utilization and finishing machining operations, in comparison with other possible combinations [47].…”

Microwave Sintering of Ti6Al4V: Optimization of Processing Parameters for Maximal Tensile Strength and Minimal Pore Size

“…Titanium alloy Ti6Al4V, a highly-preferred material in aerospace and biomedical industries due to its mechanical and biocompatibility properties, suffers from poor machinability. Given the higher cost of titanium, the use of subtractive processes is not an economical approach due to the material wastage [1]. Additive processes produce near net-shape components and can replicate complex shapes with simple tooling.…”