AIWIN—a fast and jigless inspection technique for machined parts

Precision inspection of manufactured components having multiple complex surfaces and variable tolerance definition is an involved, complex and time-consuming function. In routine practice, a jig is used to present the part in a known reference frame to carry out the inspection process. Jigs involve both time and cost in their development, manufacture and use. This paper describes ‘as is where is inspection’ (AIWIN), a new automated inspection technique that accelerates the inspection process by carrying out a fast registration procedure and establishing a quick correspondence between the part to inspect and its CAD geometry. The main challenge in doing away with a jig is that the inspection reference frame could be far removed from the CAD frame. Traditional techniques based on iterative closest point (ICP) or Newton methods require either a large number of iterations for convergence or fail in such a situation. A two-step coarse registration process is proposed to provide a good initial guess for a modified ICP algorithm developed earlier (Ravishankar et al., Int J Adv Manuf Technol 46(1–4):227–236, 2010). The first step uses a calibrated sphere for local hard registration and fixing the translation error. This transformation locates the centre for the sphere in the CAD frame. In the second step, the inverse transformation (involving pure rotation about multiple axes) required to align the inspection points measured on the manufactured part with the CAD point dataset of the model is determined and enforced. This completes the coarse registration enabling fast convergence of the modified ICP algorithm. The new technique has been implemented on complex freeform machined components and the inspection results clearly show that the process is precise and reliable with rapid convergence.     

Dynamic performance of a cable with an inspection robot — analysis, simulation, and experiments

A special cable inspection robot is designed to inspect automatically the cables of a cable-stayed bridge. The free vibration equation of the cable-robot system is derived firstly to study the dynamic characteristics and safety performance of the system. Then, the effect of the robot on the cable natural frequency is discussed, and the dynamic response equation when a robot is climbing at a constant speed is deduced. Furthermore, the effect of the cable vibration on the robot’s climbing ability is studied. The natural frequency characteristics of the robot are analyzed and optimized to avoid the resonance between the cable and the robot, using a finite element model. Additionally, dynamic cable responses are simulated under different conditions wherein the robot mass are 10 and 200 kg, and the speeds are 0.2 and 0.3 m/s, respectively. At last, to demonstrate further the dynamic characteristics of the cable-robot system experimentally, cables are set up on the Junshan highway bridge over the Yangtze river. Similar experimental models of these cables are constructed, and vibration experiments are conducted to validate the theoretical calculation. The results show that a light robot has little effects on the cable vibration amplitude and vibration acceleration; this confirms the safety of the cable.     

Current challenges and potential directions towards precision microscale additive manufacturing – Part II: Laser-based curing,heating, and trapping processes

This article is the second in a four-part series of articles providing an overview of the challenges and opportunities in microscale additive manufacturing (AM) processes with applications in fabrication of high precision micro/nano-products. Laser-based microscale additive manufacturing processes are discussed this article. Compared to the other AM processes, laser-based processes provide several unique advantages, especially in terms of a wide variety of processable materials and high volumetric throughputs. The processes discussed in this paper can fabricate complex microscale features with minimum resolutions ranging from hundreds of nanometers to hundreds of microns. However, there are several fundamental limits and trade-offs which hinder the scalability of these processes. The paper discusses the limits to the materials, resolution, geometry, and volumetric throughput and proposes approaches to mitigate these limits and improve the scalability of laser-based microscale AM processes.     

Fibre optic distributed scattering sensing system: perspectives and challenges for high performance applications

As fiber optic distributed scattering sensing systems are providing innovative solutions for the monitoring of large structures, the comparison of different techniques and solutions is difficult because of the lack of standardized specifications and the difficulty associated to the characterization of such systems. The article presents a tentative definition of performance specifications and qualification aiming at providing clear guidelines for their design, procedures applicable to fiber optic distributed sensing systems specifications, qualification, application and selection.     

The online quality control methods for the assembling of remanufactured engines’ cylinder block and cover under uncertainty

The assembling of cylinder block and cover is one of the keys for the quality controlling of remanufactured engines. First, we analyze the critical factors which influence the assembly quality and study the uncertainty connotation of the flatness and roughness of cylinder block and cover, as well as bolts. Then, an uncertainty quantitative measure model for each factor has been structured, and according to that, we proposed a back propagation (BP) neural network-based quality control method which can achieve self-learning, updating, and online dynamic quality controlling. It can reduce the negative effects caused by the uncertainty and improve the assembly accuracy. Finally, the quality data of remanufactured engine in 2012 proves that the method can improve the qualification rate of 0.63 % and reduce the cost of after-sales claims by 35.2 %; the living examples verify its feasibility and validity.     

A Hyper-redundant Elephant’s Trunk Robot with an Open Structure: Design,Kinematics, Control and Prototype

This article reviews the status of thermomechanical analysis of the friction stir welding(FSW) process for establishing guidelines for further investigation, filling the available research gaps, and expanding FSW applications. Firstly, the advantages and applications of FSW process are introduced, and the significance and key issues for thermomechanical analysis in FSW are pointed out. Then, solid mechanic and fluid dynamic methods in modeling FSW process are described, and the key issues in modeling FSW are discussed. Di erent available mesh modeling techniques including the applications, benefits and shortcomings are explained. After that, at different subsections, the thermomechanical analysis in FSW of aluminum alloys and steels are examined and summarized in depth. Finally, the conclusions and summary are presented in order to investigate the lack of knowledge and the possibilities for future study of each method and each material.     

Current challenges and potential directions towards precision microscale additive manufacturing – Part III: Energy induced deposition and hybrid electrochemical processes

The Part III of the four-part series of articles discusses the challenges and opportunities in microscale additive manufacturing processes, specifically focusing on energy-induced deposition and electrochemical processes. Compared to the direct ink write (DIW) and laser-based processes, the energy-induced deposition methods can fabricate high-resolution, high aspect ratio and complex parts, while the hybrid electrochemical process can be used to fabricate complex parts using a wide range of conductive and photoactive materials. However, the volumetric throughput of these processes is lower than their DIW and laser-based counterparts. The processes that have been explored in this process are Focused-ion Beam Induced Deposition (FIBID), Laser Chemical Vapor Deposition (LCVD), Menicus-confined Electrodeposition (MCED) and Laser-Enabled Electrochemical Printing (LECP). The range of processable materials, feature-size resolution, geometry and volumetric throughput are used as factors to evaluate the current state-of-the-art for these processes. Novel approaches have been proposed in the article to address these challenges associated with microscale AM processes.     

Optimization of thrust force, torque, and tool wear in drilling of coir fiber-reinforced composites using Nelder–Mead and genetic algorithm methods

Machining of composite materials is an important and current topic in modern researches on manufacturing processes. Determination of optimal cutting parameters is one of the most important elements in the machinability study of composites. Optimization has significant practical importance particularly for operating the machineries. In order to increase the accuracy of drill holes, the tool must be in good condition always as much as possible. To achieve good condition of tool, the optimization of machining parameters like drill bit diameter, spindle speed, and feed rate are mandatory. The objective of this paper is to study the effect of these process parameters on thrust force, torque, and tool wear in drilling of coir fiber-reinforced composites. The optimal settings of the parameters were determined through experiments planned, conducted, and analyzed using the Box–Behnken design, Nelder–Mead, and genetic algorithm methods. This paper also aimed to increase the cutting condition of tool, i.e., minimization of tool wear by applying the optimized input parameters using Nelder–Mead and genetic algorithm techniques.     

Production, identification, and use of nanocarbon in vehicles’ frictional systems

Nanocarbon production by the decomposition of hydrocarbon gas at atmospheric pressure is considered; no catalysts are employed. The role of nanocarbon in improving the antifrictional, antiwear, and antiscratch properties of lubricants is studied.     

Production management: Beyond the dichotomy between ‘push’ and ‘pull’

Existing approaches in Japan and western countries to managing production orders are surely different. The former aims at assuring a ‘lean production’ so that items can flow without waste, where each manufacturing stage ‘pulls’ the supply of items and resources according to its own needs from stages upstream. The latter forces management to plan ‘fat production’, so that the risk of stockout can be minimized and where the loading conditions at each stage have to be ‘pushed’ by a suitable plan. Besides different work organization in plants managed by ‘push’ or ‘pull’ philosophies the goals and aims of these two approaches are complementary. This fact raises the question of taking the opportunity to integrate these two philosophies, and to originate a new production management methodology able to handle difficult economic periods through robust planning, and to track markets in equilibrium through decentralized control. The question approached in this paper is: does an, at least theoretical, integration of the two approaches exist? This contribution aims to propose an answer in terms of the potential integration of the two approaches, as suggested by the different but complementary experiences of the two authors.     

Measurement and evaluation of the apparent modulus of elasticity of apple based on Hooke’s,Hertz’s and Boussinesq’s theories

Awareness on the mechanical properties of agricultural products is necessary in order to estimate and predict the deformation of viscoelastic materials under external loads for system design, transport, processing and packaging. The aim of this study was to evaluate three theories (i.e. Hooke, Hertz and Boussinesq) on the apparent modulus of elasticity of some apple varieties i.e. Golden Delicious, Red Delicious and Granny Smith. The theoretical results were analyzed in a factorial experiment with completely randomized design with 9 treatments and 15 replicates. The results showed the practical usability of Hertz’s theory with better prediction accuracy whilst the Boussinesq’s theory showed a significant difference of predicted modulus of elasticity compared to other theories and the values reported in some publications. Although, the Hook’s theory enables the identification of a bio-yield point on its force–deformation curve, but Hertz’s theory was recommended as the most appropriate method due to easiness of working on a cylindrical sample of apple and the closer agreement with reality. Based on the results of this study, Golden Delicious and Granny Smith varieties had the lowest and the highest modulus of elasticity as 2.211 MPa and 3.431 MPa, respectively. This difference shows the firmness of apple varieties and different tissue responses to external loads and forces accordingly.     

A comparison of the tensile, fatigue, and fracture behavior of Ti–6Al–4V and 15-5 PH stainless steel parts made by selective laser melting

In this work, Ti–6Al–4V and 15-5 PH steel samples were fabricated using selective laser melting (SLM) and their tensile, fatigue, and fracture properties were analyzed and compared. The tensile properties were compared with respect to the build orientation. The horizontally built samples showed relatively better tensile properties as compared with the vertically built samples. Fatigue performance was studied for the vertical build orientation and compared with standard wrought material data. The tensile and fatigue performance of SLM-built materials were comparable to their respective standard wrought materials. Fractography was carried out for all tensile and fatigue-tested samples. The fatigue fracture behavior of Ti–6Al–4V was different from 15-5 PH steel. For Ti–6Al–4V, the fatigue crack initiation occurred deep in the subsurface whereas for PH steel the fatigue crack was initiated from the surface.     

Current challenges and potential directions towards precision microscale additive manufacturing – Part I: Direct ink writing/jetting processes

This paper is the first in a series of articles which comprehensively discuss the state-of-the-art in microscale additive manufacturing processes and present solutions to challenges impeding their scalability. In this paper, a class of additive manufacturing techniques known as Direct Ink Write/Jet Processes are explored which have been used by researchers for fabrication of microscale parts with varying geometric freedom. The paper identified the key challenges to high throughput 3D microfabrication using these processes, by analyzing the material constraints, geometric constraints, feature-size resolution limits and throughput limits. While some of these challenges can be overcome by novel precision engineering approaches, there are several others which need an acute understanding of material systems, process parameters and critical components. This paper identifies these challenges and suggests potential approaches to eliminate them with the goal of fabricating true-3D parts at high throughputs.     

三星:“星‘型’象”,新方向

<正>4月伊始,三星又迎来了新一轮品牌活动——以"星‘型’象"为主题,向全国多地辐射的创意家装设计师签约之旅。随着国内房地产业的持续升温,人们对家装行业也不在陌生。家作为都市人心灵的港湾,人们对家庭精装修的水准需求也在不断提高。电子产业的大鳄,三星也不失良机的将眼光投向家装行业。4月伊始,三星又迎来了新一轮品牌活动——以"星‘型’象"为主题,向全国多地辐射的创意家装设计师签约之旅。     

Multi-response design of Nd:YAG laser drilling of Ni-based superalloy sheets using Taguchi��s quality loss function, multivariate statistical methods and artificial intelligence

This paper presents a hybrid design strategy for the determination of the optimum laser drilling parameters which simultaneously meets the requirements for seven quality characteristics (responses) of the holes produced during pulsed Nd:YAG laser drilling of a thin sheet of nickel-based superalloy Nimonic 263. The process was designed using two approaches based on the experimental data. In the first approach, the quality losses of seven correlated responses were uncorrelated into a set of components using the principal component analysis; then the grey relational analysis was applied to synthesise components into a synthetic performance measure. Since this approach considered only parameter values used in the experiment, the second approach was developed to find the global optimal parameters solution using an artificial neural network to model the relation between parameters and a synthetic performance measure, and a genetic algorithm to perform a search for the global optimum in a continual multidimensional space. The analysis of the application indicated that the proposed approaches gave a better result, in terms of the optimal parameter settings that yield the maximal synthetic performance measure, than several commonly used methods for multi-response process parameters design. The results demonstrated that the robust Nd:YAG laser drilling of Ni-based superalloy sheets was designed with respect to the requirements for seven quality characteristics of the drilled holes, by using the proposed strategy.