PRECISION POLISHING DYNAMICS: THE INFLUENCE OF PROCESS VIBRATIONS ON POLISHING RESULTS

The optical pitch polishing process has been used over 300 years to obtain high quality optical surface finish with little subsurface damage. A pitch tool consists of a metal platen coated with a layer of polishing pitch whereby pitch is a highly viscoelastic material. In polishing the workpiece is rubbed against the tool while abrasive slurry is supplied in between them. During polishing the workpiece is subjected to process vibrations, whereby be these vibrations are generated by the machine itself due to moving parts, or that are transmitted from the shop floor through the machine to the workpiece. To date, little is available in the public domain regarding the role of process induced vibrations on polishing outcomes. This research investigates such vibrations, how they transfer through the pitch layer on the tool, and ultimately how they affect the material removal rates and surface finishes obtainable on fused silica workpieces. Fundamental understandings with respect to the process vibration will reduce the heuristic nature of pitch polishing and generate deterministic polishing outcomes. Key findings include the following. The pitch selection has little influence on the magnitude or range of process vibrations transmitted through the tool to the workpiece in the 1 Hz to 16 kHz range. Within the same frequency bandwidth the recorded process vibrations are in the range of 0.2 to 10 nm and the main factors found to affect their magnitude include; the polishing machine itself, process speeds, and the use of passive damping materials in the tool construction. Material removal rates and surface finishes obtained on fused silica workpieces were found to be sensitive to the extent of the process vibrations. Up to 30% changes in the material removal rates were observed with increasing vibrational magnitudes. The higher level vibrations were also found to have a negative impact on the finishes obtained in the lower spatial domains. Additional testing on a specifically made test-bed demonstrated a linear correlation between the material removal rates and the vibrational power input. This relationship was further explored by adding external vibrational sources to an existing machine, and as expected the increased vibrational power resulted in 80% higher material removal rates. The results from this experimental work facilitated Dr. Keanini’s development of a vibrational based material removal model. Additional polishing tests combined with surface topography analysis of both hard and soft pitch tools demonstrated the robustness of the proposed model to accommodate the influence of different pitch grades. The summary in general is that in pitch polishing the process vibrations are important to monitor and control for process optimization

PRECISION POLISHING DYNAMICS: THE INFLUENCE OF PROCESS VIBRATIONS ON POLISHING RESULTS

The optical pitch polishing process has been used over 300 years to obtain high quality optical surface finish with little subsurface damage. A pitch tool consists of a metal platen coated with a layer of polishing pitch whereby pitch is a highly viscoelastic material. In polishing the workpiece is rubbed against the tool while abrasive slurry is supplied in between them. During polishing the workpiece is subjected to process vibrations, whereby be these vibrations are generated by the machine itself due to moving parts, or that are transmitted from the shop floor through the machine to the workpiece. To date, little is available in the public domain regarding the role of process induced vibrations on polishing outcomes. This research investigates such vibrations, how they transfer through the pitch layer on the tool, and ultimately how they affect the material removal rates and surface finishes obtainable on fused silica workpieces. Fundamental understandings with respect to the process vibration will reduce the heuristic nature of pitch polishing and generate deterministic polishing outcomes. Key findings include the following. The pitch selection has little influence on the magnitude or range of process vibrations transmitted through the tool to the workpiece in the 1 Hz to 16 kHz range. Within the same frequency bandwidth the recorded process vibrations are in the range of 0.2 to 10 nm and the main factors found to affect their magnitude include; the polishing machine itself, process speeds, and the use of passive damping materials in the tool construction. Material removal rates and surface finishes obtained on fused silica workpieces were found to be sensitive to the extent of the process vibrations. Up to 30% changes in the material removal rates were observed with increasing vibrational magnitudes. The higher level vibrations were also found to have a negative impact on the finishes obtained in the lower spatial domains. Additional testing on a specifically made test-bed demonstrated a linear correlation between the material removal rates and the vibrational power input. This relationship was further explored by adding external vibrational sources to an existing machine, and as expected the increased vibrational power resulted in 80% higher material removal rates. The results from this experimental work facilitated Dr. Keanini’s development of a vibrational based material removal model. Additional polishing tests combined with surface topography analysis of both hard and soft pitch tools demonstrated the robustness of the proposed model to accommodate the influence of different pitch grades. The summary in general is that in pitch polishing the process vibrations are important to monitor and control for process optimization

Remanufacturing and Advanced Machining Processes for New Materials and Components

"Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems.

Remanufacturing and Advanced Machining Processes for New Materials and Components

Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems

Remanufacturing and Advanced Machining Processes for New Materials and Components

Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems

Remanufacturing and Advanced Machining Processes for New Materials and Components

"Remanufacturing and Advanced Machining Processes for Materials and Components presents current and emerging techniques for machining of new materials and restoration of components, as well as surface engineering methods aimed at prolonging the life of industrial systems. It examines contemporary machining processes for new materials, methods of protection and restoration of components, and smart machining processes. • Details a variety of advanced machining processes, new materials joining techniques, and methods to increase machining accuracy • Presents innovative methods for protection and restoration of components primarily from the perspective of remanufacturing and protective surface engineering • Discusses smart machining processes, including computer-integrated manufacturing and rapid prototyping, and smart materials • Provides a comprehensive summary of state-of-the-art in every section and a description of manufacturing methods • Describes the applications in recovery and enhancing purposes and identifies contemporary trends in industrial practice, emphasizing resource savings and performance prolongation for components and engineering systems The book is aimed at a range of readers, including graduate-level students, researchers, and engineers in mechanical, materials, and manufacturing engineering, especially those focused on resource savings, renovation, and failure prevention of components in engineering systems.

DEVELOPMENT OF A LOW COST PRECISION POLISHING MACHINE BASED ON PARALLEL KINEMATIC SYSTEM

The increasing demand on mass production of high precision parts, has pushed the precision manufacturing industry to develop reliable precision finishing processes such as Bonnet polishing to address market requirements. Indeed, the nature of the surface to be polished plays an important role in the design of a possible polishing machine. A gap within the research in polishing for precision industry needs has been identified. Small parts with <50mm x 50mm and possible freeform curvature containing small slopes cannot be polished with available bonnet polishing (BP) processes on market. This is caused by the tool head size and the tool holder being bigger than part curvature or the part itself. Although, the BP process has a huge potential for surface roughness improvement and form accuracy, it is generally seen in industry as an expensive solution for a non-deterministic finishing process. Therefore, this project has sought to develop a BP machine to cover the gap with an innovative and inexpensive design. In order to develop a machine which responded to the market expectations all possible requirements were listed from a customer point of view. Based on the requirement, a machine concept was produced. Market analysis helped to identify sub-systems of the machine. FEA analysis of the design was performed to check for stress distribution and displacement due to its own mass. Additional assembly parts are designed and a prototype of the machine was produced. The designed machine is tested for its ability as precision polishing machine. Flat surfaces of P20 tool steel were targets for polishing to nanometric surface finishes. Empirical experiments helped to identify parameters which influenced the surface roughness. Taguchi method were then used to optimise the parameters for better surface roughness. Optimum parameters conditions helped to reach less than 10 nm Ra systematically and repeatedly. The samples were also polished using re-circulating slurry techniques, and the obtained results were discussed. Further, pre polishing, Grolishing processes capable of improving surface roughness from ground finish to mirror like finish were developed for cost effective manufacturing procedures. The material removal was analysed to identify parameters capable of improving surface roughness over a step grolishing process. Two grolishing procedures were developed. Both processes produced nanometric range surface finishes. Other variations in results were compared and discussed. Although, machine axis has the ability to produce freeform movement, tool holders need to be improved to facilitate the identification of the distance between tool origin and workpiece origin. Therefore, a new spindle holder assembly is produced to hold the tool and an optical measurement device DRI used to evaluate accurately the distance separating the tool-workpiece origin and further align the workpiece inclination with respect to the machine axis. A CAD-CAM package is also developed to generate programme capable of performing freeform curvature

Advances in Micro and Nano Manufacturing: Process Modeling and Applications

Micro- and nanomanufacturing technologies have been researched and developed in the industrial environment with the goal of supporting product miniaturization and the integration of new functionalities. The technological development of new materials and processing methods needs to be supported by predictive models which can simulate the interactions between materials, process states, and product properties. In comparison with the conventional manufacturing scale, micro- and nanoscale technologies require the study of different mechanical, thermal, and fluid dynamics, phenomena which need to be assessed and modeled.This Special Issue is dedicated to advances in the modeling of micro- and nanomanufacturing processes. The development of new models, validation of state-of-the-art modeling strategies, and approaches to material model calibration are presented. The goal is to provide state-of-the-art examples of the use of modeling and simulation in micro- and nanomanufacturing processes, promoting the diffusion and development of these technologies