Application of a Linear Center Identification Scheme to Deterministic Polar Positioning

In a number of manufacturing applications, parts of circular cross-section must be centered for optimal processing or measurement. However, part form is never perfect, making accurate determination of the “centered” state of a part difficult. Imperfect inputs to the manufacturing process such as rough-processed parts, deformation due to heat treatment, or raw formed materials present difficulty in centering by the traditional manual method. This paper presents a filtering and quantification technique for identifying the true center of an imperfect round part through isolation of the lowest polar frequency component. A low-cost device is presented that centers parts based on this frequency domain identification of center

Uncertainty estimation of shape and roughness measurement

One of the most common techniques to measure a surface or form is mechanical probing. Although used since the early 30s of the 20th century, a method to calculate a task specific uncertainty budget was not yet devised. Guidelines and statistical estimates are common in certain cases but an unambiguous method for all kinds of measurements and measurement tasks is absent.Anew method, the virtual measurement machine, already successfully implemented in CMMs, is now applied on a specific group of stylus measurement instruments namely for: • roughness; • roundness; • contracers (form measurement). Each of these types of machines use the same measurement principle; a stylus is pressed against the object with a well specified force, moved across the object and the trajectory of the stylus tip is registered. The measurement process and its disturbances can be described theoretically and mathematically. Each disturbance or influencing factor which contributes to the uncertainty of the measurement is modeled and with this model simulated (virtual) measurements are generated. The virtual measurement depends upon the magnitude and range of the influencing factor. Some examples of influencing factors are; tip geometry, measurement force, probe gain factors, squareness of measurement axes, etc... The sensitivity of each factor upon the measurement is calculated with so-called virtual measurements. Recalculation of the describing parameters of the measured object with the virtual measurements gives the amount of uncertainty attributed to the influencing factor or machine parameter. The total uncertainty budget is composed out of each contribution in uncertainty of each machine parameter. The method is successfully implemented on two machines: the SV 624-3D (roughness and shape) and theRA2000 (roundness, form and cylindricity). It is shown that an on-line uncertainty budget can be calculated specifying each contributor. As not only gain factors need to be calibrated, but more input variables, e.g. calibration data of machine parameters, are required by the uncertainty calculation, calibration artefacts are developed to perform such a task. The artefacts can be used to perform a total and fast calibration on the shopfloor directly traceable to the appropriate primary standard. Combining the virtual measurement machine, implemented for roughness, roundness and form in high quality software, with the calibration artefacts, a powerful measurement tool is realised which allows to calculate a task specific uncertainty budget for these types of machines and creates a traceable measurement result which can be accredited by accreditation organizations

ANALYSIS OF SURFACE INTEGRITY IN MACHINING OF CFRP UNDER DIFFERENT COOLING CONDITIONS

Carbon Fiber Reinforced Polymers (CFRP) are a class of advanced materials widely used in versatile applications including aerospace and automotive industries due to their exceptional physical and mechanical properties. Owing to the heterogenous nature of the composites, it is often a challenging task to machine them unlike metals. Drilling in particular, the most commonly used process for component assembly is critical especially in the aerospace sector which demands parts of highest quality and surface integrity. Conventionally, all composites are machined under dry conditions. While there are drawbacks related to dry drilling, for example, poor surface roughness, there is a need to develop processes which yield good quality parts. This thesis investigates the machining performance when drilling CFRP under cryogenic, MQL and hybrid (CryoMQL) modes and comparing with dry drilling in terms of the machining forces, delamination, diameter error and surface integrity assessment including surface roughness, hardness and sub-surface damage analysis. Additionally, the effect of varying the feed rate on the machining performance is examined. From the study, it is concluded that drilling using coolant/ lubricant outperforms dry drilling by producing better quality parts. Also, varying the feed rate proved to be advantageous over drilling at constant feed

Grinding cycle control project 1967

An investigation has been made into the sequential control of a grinding machine using electro—pneumatic, ball valve and wall attachment switching elements. Each system has been tested on a grinding cycle simulator and also to a limited extent when applied on a grinding machine. A technical assessment has been made of each system. In the case of the pure fluid system it was necessary to design and build an amplifying and switching circuit before the tests could be carried out and reports are presented of these investigations

Designing for Additive Manufacturing - Product and Process Driven Design for Metals and Polymers

Additive Manufacturing (AM) has broken through to common awareness and to wider industrial utilization in the past decade. The advance of this young technology is still rapid. In spoken language additive manufacturing is referred as 3D printing for plastic material and additive manufacturing is left as an umbrella term for other materials i.e. metallic materials and ceramics. As the utilization of AM becomes more widespread, the design for additive manufacturing becomes more crucial as well as its standardization. Additive manufacturing provides new set of rules with different design freedom in comparison with subtractive manufacturing methods. This is thought to empower product driven designs. However, in the AM methods there are process driven variables that limit the designs functions to what could be manufactured. There are often extra steps after production to finalize the design. Topology optimization utilizes product driven design where material is only where it is needed to be. The design is computed without taking into account any manufacturing constrains and only the design in the final application stage is achieved. Topology optimization algorithm is explored in detail for two algorithms. Then these algorithms are compared in case study I to gain better understanding of the algorithms functions. Case study I consists of 2D and 3D algorithms where a 3D level set method algorithm was written for this purpose. The concept of designing for additive manufacturing is examined for polymeric materials in case study II with a help of topology optimization design software tailored for additive manufacturing market. The parts are manufactured with different AM methods, examined and results are explained. The results show an interesting effect of anisotropy and the manufacture methods effect in the part mechanical properties. On the other hand, process driven design and its concepts important as the manufacturing method dictates, what can and should be done economically. Metal AM process constraints are explored in case study III through accuracy studies in metal additive manufacturing at laser powder bed fusion (LPBF) technology. Accuracy and surface studies are concluded to gain a better understanding of the process and manufacturability of metal parts. The gain knowledge is explaned and examples are shown how these are utilized to make metal parts with tailored properties and with minimal post processing needs

Superconducting gyroscope research

Four basic areas of research and development of superconducting gyroscopes are studied. Chapter 1 studies the analysis of a SQUID readout for a superconducting gyroscope. Chapter 2 studies the dependence of spin-up torque on channel and gas properties. Chapter 3 studies the theory of super fluid plug operation. And chapter 4 studies the gyro rotor and housing manufacture

Design Guide for Bearings Used in Cryogenic Turbopumps and Test Rigs

Cryogenic bearings are a unique and specialized area of the overall group of bearings that are used every day in industrial and aerospace applications. Cryogenic bearings operate in a unique environment that is not experienced by most bearing applications. The high speeds of turbomachinery, flow of cryogenic coolants, use of nonstandard materials, and lack of lubrication place unique demands on cryogenic bearings that must be met for the safety and success of the mission. To meet the goals of safety and success, requirements are put on the designer, manufacturer, and user that are not normally applied to off-the-shelf bearings. The designer has to have knowledge of the operating conditions, rotational speeds, loads, stresses, installation methods, inspection criteria, dimensional requirements, and design and analytical tools. The manufacturer needs to be aware of the materials used for cryogenic bearings, special heat treatments required, cleanliness of the processes, and inspection techniques to ensure a good product. The user needs to be aware of the safe handling practices to eliminate corrosion and debris, correct installation and removal procedures, pre- and post-test inspections, and the documentation that follow the bearings. This guide is based on the experiences of engineers at NASA Marshall Space Flight Center (MSFC) that have been involved in bearing research and testing along with specific bearing references that have been written. It is not meant to be a bearing design textbook for cryogenic bearing applications. These are available from many authors. Its purpose is to help the designer, manufacturer, or user in the application of cryogenic bearings to better understand the requirements placed on these bearings

INNOVATIVE DRILLING TECHNOLOGIES FOR ADVANCED MATERIALS

Carbon fibre reinforced polymer (CFRP) composites are among the most widely used composite materials in the aerospace industry, thanks to the high specific mechanical properties offered. These composites combine the fundamental aeronautical requirements of lightness and strength, which have sparked great research interest in improving the properties and the production process of composite materials. CFRP composites can be manufactured in near net shape; however, they often require further machining processes such as drilling, particularly for joining purposes. Fibre orientation plays a fundamental role in CFRP composite materials, affecting the mechanism of chip formation and the quality of the cut surface and making machining of CFRP a challenging task. Proper optimisation of the drilling process can substantially improve CFRP parts quality, which may be affected by several faults generated during the process. In order to simplify the assembly operations and reduce manufacturing costs, efforts are increasingly spent with the aim to optimise CFRP drilling

Development of advanced coating for enhancing performance of internal combustion engine

Government has mandated all the automakers to increase their vehicle fleet miles per gallon average (MPG) to mitigate the global warming effects. Automakers have to find ways to reduce vehicle weight and frictional loss between powertrain components to increase the MPG, a higher MPG can help to reduce the vehicle fuel consumption and emissions. One popular approach is to remove the cast iron cylinder block liners and replace them with a lighter more thermally efficient material to reduce engine weight and enhance engine performance with higher power output or higher fuel efficiency. In this work, electrolyte jet plasma oxidation (EJPO) coating was the first time to be applied on engine cylinder bore and other components to enhance engine performance, reduce weight and cost. EJPO coating is a kind of aluminum oxidation coating which has high hardness, high corrosion resistance, low coefficient of friction (COF) and good thermal properties. Lab tribology tests and thermal investigation showed EJPO coating had 65% lower COF than cast iron and 50% lower than plasma transfer wire arc (PTWA) coating, and better thermal properties. EJPO coated 2.0 L and 5.0 L engines were tested and compared with cast iron liner engine and PTWA coated engine. EJPO coated 2.0 L engine passed Break-in test, Power test and 100 hours engine fatigue test. Compared with cast iron liner 2.0 L engine, EJPO coated 2.0 L engine had higher power output, especially at speeds lower than 3000 rpm and speeds higher than 5000 rpm. EJPO coated 2.0 L engine block reduced weight around 6.4% and reduce cost around 17.5%. EJPO coated 5.0 L engine passed Break-in test, Power test and vehicle durability test. Compared with PTWA coated 5.0 L engine, the EJPO coated 5.0 L engine had higher power output at speeds lower than 3000 rpm and the EJPO coated camshaft bores, piston crown and cylinder head dome enhanced the performance more at high speeds. EJPO coated 5.0 L engine block reduced weight around 2% and reduce cost around 9% compared with PTWA coated one. EJPO coating’s lower COF and thermal swing property contributed to the higher engine performance. Lower COF helped to reduce engine friction loss, and the thermal swing property helped to reduce the engine heat loss without heating up the intake air temperature. EJPO coating process and honing process parameters for 2.0 L and 5.0 L aluminum engine blocks were developed and the engine cylinder bore coating thickness, coating roughness, and piston to bore clearance were found in this work. EJPO coating is a potential candidate material for internal combustion engine to enhance performance, reduce weight, cost and increase the MPG in the future