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Precision Engineering is defined as painstaking attention to detail and requires knowledge of a wide variety of measurement, fabrication, and control issues. Increasing the precisionthe accuracy and repeatability of a mechanism or process is critical to our countrys Competitive position in the world of high technology.
Precision Machining Introduction to Precision Engineering and Precision machining What is Precision Engineering? • Precision Engineering is defined as painstaking attention to detail and requires knowledge of a wide variety of measurement, fabrication, and control issues • Increasing the precision the accuracy and repeatability of a mechanism or process is critical to our country's Competitive position in the world of high technology What is Precision Engineering? • The Precision Engineering focuses on many areas: – – – – * research, design, development, manufacture and measurement of high accuracy components and systems precision controls, metrology, interferometry, materials, materials processing, nanotechnology, optical fabrication, precision optics, precision replication, scanning microscopes, semiconductor processing, standards and ultra-precision machining What is Precision Engineering? • The precision engineering toolbox includes: – design methodology, – error budgeting, – Uncertainity analysis, – metrology, – calibration/error compensation, – precision controls and actuators and sensors Why Precision Engineering? • Improve Product Performance – – – – Accuracy Reliability Improved Life Safety • Increase Manufacturability – Automatic Assembly • Lower Costs – Circuit Integration • Advance Science And Technology Precision Engineering • Design and Production Systems – Lifecycle engineering, Product & process modeling, Design theory, CAD/CAM/CAE, Rapid prototyping, Automated & intelligent systems, Production management, MES, CIM, etc • Precision Machining – Cutting, Abrasive machining, Planarization (CMP etc), Micromachining, EDM, Energy beam machining, Injection molding, Deposition (PVD, CVD), Nanomachining, etc • Mechatronics – Micromachines, Intelligent robots, Information instruments, Precision positioning, Machine tool & tooling, Intelligent control, Mechanism & mechanical elements, etc Precision Engineering • Metrology – Image processing, Optronics, 3D shape measurement, Surface & roughness measurement, Intelligent data analysis, SPM, Inprocess measurement, Surface and Microform Metrology, Nanoscale Metrology, etc • Humans and Environment – Human engineering, Welfare engineering, Biomedical precision engineering, Biomedical measurement, Environmental machine & ecomachining, Amusement machine, Techno-history, Human skill, etc Precision Engineering • It includes the analysis and design of components as well as machines and instruments • The analysis of components includes modeling, simulation and prototype behavior Elements of research are: – – – – – structural loop components bearing behavior driving system guiding elements probing systems Precision Engineering • Important research activities are: – structural loop design including materials – thermal loop design – static behavior analysis (FEM) – dynamic analysis and simulation of machine elements and electro-mechanical servo systems – design and validation of precision machinery prototypes: • single point diamond turning machines • high precision measuring machines • high precision probing systems Four classes of achievable machining accuracy Four classes of achievable machining accuracy Four classes of achievable machining accuracy Normal Machining • In this class of machining, the conventional engine lathe and milling machines are the most appropriate machine tools that can be used to manufacture products such as gears and screw threads to an accuracy of, for example, 50 μm Normal Machining Precision Machining • Machining integrated circuit chips on a CNC Milling Machine The grinding of a silicon wafer (Integrated Circuit Chips) using a CNC milling machine is a precision machining process Figures shows an IC silicon chip before and after grinding it on a MAHO CNC vertical milling machine Precision Machining • 006>ABA!"'=A' The grinding of a silicon wafer (Integrated Circuit Chips) using a CNC milling machine is a precision machining process High-Precision Machining • High-precision CNC diamond turning machines are available for diamond mirror machining of components such as [3]: • (a) Computer magnetic memory disc substrates • (b) Convex mirrors for high output carbon dioxide laser resonators • (c) Spherical bearing surfaces made of beryllium, copper, etc • (d) Infrared lenses made of germanium for thermal imaging systems • (e) Scanners for laser printers • (f) X-ray mirror substrates High-Precision Machining Both lapping and polishing are considered to be high-precision machining operations Although the grinding of an IC silicon die discussed earlier falls under Taniguchi’s second class of machining-precision machining, the machining of the PCB of the IC after completely removing the silicon die substrate essentially falls under high-precision machining This operation tends to expose the transistors in the layers of the PCB Figure depicts a typical high-precision machined PCB in which transistors in a layer are exposed High-Precision Machining Polishing of hard and brittle materials such as silicon wafers on a three-axis polishing machine An LP600 precision Lapping and Polishing Machine Ultra-Precision Machining • Taniguchi [5] has referred to “ultra-precision machining” as a process by which the highest possible dimensional accuracy is or has been achieved at a given point in time Also, it is referred to as the achievement of dimensional tolerances of the order of 0.01 μm and a surface roughness of 0.001 μm (1 nm) The dimensions of the parts or elements of the parts produced may be as small as μm, and the resolution and the repeatability of the machine used must be of the order of 0.01 μm (10 nm) Ultra-Precision Machining The accuracy targets for ultra-precision machining cannot be achieved by a simple extension of conventional machining processes and techniques The Figure shows the dimensions of an integrated circuit (IC) specified to 0.1 μm and indicates the requirement for ultra-precision machining accuracy capability of the order of 0.005 μm (5 nm) Ultra-Precision Machining Nanoform 200 (Figure 1.25) has viable features for carrying out ultra-precision work The machine has a high performance, ultra-precision machining system designed for the most demanding aspherical turning and grinding applications It has a swing diameter capacity of 700 mm and can be utilized for single-point diamond turning and peripheral grinding Ultra-Precision Machining • • • • • • The most noteworthy developments in processes capable of providing ultra-precision are as follows : (a) Single-point diamond and cubic boron nitride (CBN) cutting (b) Multi-point abrasive cutting/burnishing, for example, in diamond and CBN grinding, honing, etc (c) Free abrasive (erosion) processes such as lapping, polishing, elastic-emission machining and selective chemico-mechanical polishing (d) Chemical (corrosion) processes such as controlled etch machining (e) Energy beam processes (removal, deformation and accretion) including those given below: – – – – – – – – (i) Photon (laser) beam for cutting, drilling transformation hardening and hard coating (ii) Electron beam for lithography, welding (iii) Electrolytic jet machining for smoothing and profiling (iv) Electro-discharge (current) beam (EDM) for profiling (v) Electrochemical (current) (ECM) for profiling (vi) Inert ion beam for milling (erosion) micro profiling (vii) Reactive ion beam (etching) (viii) Epitaxial crystal growth by molecular-bit accretion for manufacturing new super-lattice crystals, etc Review questions • • • • • • • • • 1.1 Explain with sketches the difference between accuracy and precision 1.2 (a) Discuss the achievable machining accuracy for normal, precision, high-precision and ultra-precision machining (b) Highlight some mechanical, electronic, and optical components, their tolerances and their machining aspects (c) Describe with sketches one component from each one of the above categories 1.3 Figure on page 16 shows the development of overall machining precision starting from the early 1900s State the machining accuracy achieved in 2000 for: (a) Normal machining (b) Precision machining (c) High-precision machining (d) Ultra-precision machining ... from the early 1900s State the machining accuracy achieved in 2000 for: (a) Normal machining (b) Precision machining (c) High -precision machining (d) Ultra -precision machining ... MES, CIM, etc • Precision Machining – Cutting, Abrasive machining, Planarization (CMP etc), Micromachining, EDM, Energy beam machining, Injection molding, Deposition (PVD, CVD), Nanomachining, etc... perspective of machining precision Four classes of achievable machining accuracy Four classes of achievable machining accuracy Four classes of achievable machining accuracy Normal Machining • In