Review of industrial temperature measurement technologies and research priorities for the thermal characterisation of the factories of the future

As the largest source of dimensional measurement uncertainty, addressing the challenges of thermal variation is vital to ensure product and equipment integrity in the factories of the future. While it is possible to closely control room temperature, this is often not practical or economical to realise in all cases where inspection is required. This article reviews recent progress and trends in seven key commercially available industrial temperature measurement sensor technologies primarily in the range of 0 °C–50 °C for invasive, semi-invasive and non-invasive measurement. These sensors will ultimately be used to measure and model thermal variation in the assembly, test and integration environment. The intended applications for these technologies are presented alongside some consideration of measurement uncertainty requirements with regard to the thermal expansion of common materials. Research priorities are identified and discussed for each of the technologies as well as temperature measurement at large. Future developments are briefly discussed to provide some insight into which direction the development and application of temperature measurement technologies are likely to head

Real-time laser tracker compensation of a 3-axis positioning system—dynamic accuracy characterization

The concept of integrating metrology systems into production processes has generated significant interest in industry due to its potential in reducing production time and defective parts. One of the most interesting methods of integrating metrology into production is the usage of external metrology systems to compensate machine tools and robots in real time. Continuing the work described in our previous paper of a prototype laser tracker-assisted 3-axis positioning system (Wang and Maropoulos Int J Adv Manuf Technol 69(1-4): 919-933, 2013), this paper describes experimental results of the dynamic path accuracy tests of the machine under real-time laser tracker compensation. Experiments show that the real-time corrections of the machine tool’s absolute volumetric error have significantly increased the dynamic path accuracy of the machine. This result is also validated by a ballbar acting as an independent measurement instrument, reducing the 95th percentile error from 60 μm to less than 10 μm, without any prior calibration or error mapping, showing that the proposed methods are feasible and can have very wide applications.</p

Research on rework strategies for reconfigurable manufacturing system considering mission reliability

Rework strategies that involve different checking points as well as rework times can be applied into reconfigurable manufacturing system (RMS) with certain constraints, and effective rework strategy can significantly improve the mission reliability of manufacturing process. The mission reliability of process is a measurement of production ability of RMS, which serves as an integrated performance indicator of the production process under specified technical constraints, including time, cost and quality. To quantitatively characterize the mission reliability and basic reliability of RMS under different rework strategies, rework model of RMS was established based on the method of Logistic regression. Firstly, the functional relationship between capability and work load of manufacturing process was studied through statistically analyzing a large number of historical data obtained in actual machining processes. Secondly, the output, mission reliability and unit cost in different rework paths were calculated and taken as the decision variables based on different input quantities and the rework model mentioned above. Thirdly, optimal rework strategies for different input quantities were determined by calculating the weighted decision values and analyzing advantages and disadvantages of each rework strategy. At last, case application were demonstrated to prove the efficiency of the proposed method

Design for measurement assisted determinate assembly (MADA) of large composite structures

This paper describes how Measurement Assisted Determinate Assembly (MADA) can facilitate the lean production of aerospace structures, provided that the structure is designed for MADA. A novel wingbox design and production process is used to illustrate this. The aerospace industry has not benefited from the significant reductions in production cost and cycle time that can result from greater assembly efficiency, part-to-part interchangeability and the use of flexible automation. This is largely due to the very high accuracies required across large scale assemblies. The use of metrology can reduce process steps, reduce the reliance on costly hard tooling, reduce the requirement for manually intensive and time consuming re-working at late stages of assembly, and allow low cost flexible automation to place tools to the required accuracies. The generic MADA process is presented together with guidelines for the design of structures to enable MADA

The Laser MicroJet® (LMJ) - A multi-solution technology for high quality micro-machining

The field of laser micromachining is highly diverse. There are many different types of lasers available in the market. Due to their differences in irradiating wavelength, output power and pulse characteristic they can be selected for different applications depending on material and feature size [1], The main issues by using these lasers are heat damages, contamination and low ablation rates, This report examines on the application of the Laser MicroJet® (LMJ), a unique combination of a laser beam with a hair-thin water jet as a universal tool for micro-machining of MEMS substrates, as well as ferrous and non-ferrous materials. The materials include gallium arsenide (GaAs) & silicon wafers, steel, tantalum and alumina ceramic. A Nd:YAG laser operating at 1064 nm (infra red) and frequency doubled 532 nm (green) were employed for the micro-machining of these materials

A novel algorithm of posture best fit based on key characteristics for large components assembly

Measurement and variation control of geometrical Key Characteristics (KCs), such as flatness and gap of joint faces, coaxiality of cabin sections, is the crucial issue in large components assembly from the aerospace industry. Aiming to control geometrical KCs and to attain the best fit of posture, an optimization algorithm based on KCs for large components assembly is proposed. This approach regards the posture best fit, which is a key activity in Measurement Aided Assembly (MAA), as a two-phase optimal problem. In the first phase, the global measurement coordinate system of digital model and shop floor is unified with minimum error based on singular value decomposition, and the current posture of components being assembly is optimally solved in terms of minimum variation of all reference points. In the second phase, the best posture of the movable component is optimally determined by minimizing multiple KCs' variation with the constraints that every KC respectively conforms to its product specification. The optimal models and the process procedures for these two-phase optimal problems based on Particle Swarm Optimization (PSO) are proposed. In each model, every posture to be calculated is modeled as a 6 dimensional particle (three movement and three rotation parameters). Finally, an example that two cabin sections of satellite mainframe structure are being assembled is selected to verify the effectiveness of the proposed approach, models and algorithms. The experiment result shows the approach is promising and will provide a foundation for further study and application. © 2013 The Authors

Metrology Enhanced Tooling for Aerospace (META): Strategies for Improved Accuracy of Jig Built Structures

The accuracy of many aerospace structures is limited by the accuracy of assembly tooling which is in turn limited by the accuracy of the measurements used to set the tooling. Further loss of accuracy results from different rates of thermal expansion for the components and tooling. This paper describes improved tooling designs and setting processes which have the potential to significantly improve the accuracy of aerospace structures. The most advanced solution described is environmentally isolated interferometer networks embedded within tooling combined with active compensation of component pick-ups. This would eliminate environmental effects on measurements while also allowing compensation for thermal expansion. A more immediately realizable solution is the adjustment of component pick-ups using micrometer jacking screws allowing multilateration to be employed during the final stages of the setting process to generate the required offsets