A Further Discussion on Trends in the Development of Advanced Manufacturing Technology

This paper is a supplement to “Trends in the Development of Advanced Manufacturing Technology” (Yang and Wu in Chin. J. Mech. Eng., 39: 73, 2003) but delves deeper into it. It first points out the strategic status of manufacturing industry in state development. Then, a detailed analysis is given on the features and trends in the development of advanced manufacturing technology in a total of 12 points from three aspects: “precision,” “extreme,” and “culture” from the aspect of the product itself; “green,” “rapidness,” “saving,” and “efficiency” during the manufacturing process; and “digit,” “auto,” “integration,” “networking,” and “intelligence” in view of the manufacturing method. In addition, it emphasizes that all the above aspects should be based on two base points: “manufacture” and “machinery.” Finally, it puts forth the guiding ideologies for the development of advanced manufacturing technology and the aspects China should give priority to in development, while stressing on the principles of independence, innovation and “human orientation.”     

Proposal of new eco-manufacturing feature interaction-based methodology in CAD phase

Following the environmental crises of recent decades, a turning point in the awareness of the fragility of ecosystems has been marked, i.e., environmental awareness. This has contributed to the development of various environmental laws and regulations such as the “Waste Electrical and Electronic Equipment,” the “Restriction of Hazardous Substances,” and the “Registration, Evaluation, Authorization and Restriction of Chemicals” regulations and the “Energy Using Products” Directives. Our work contributes to the development of eco-friendly product manufacturing processes. In order to estimate and optimize the environmental impacts of a product, most of the methodologies, concepts, and tools that integrate computer-aided design (CAD) and life cycle assessment systems generally exploit the feature technology at the level of each feature independently of the others, i.e., “microplanning.” The feature interaction technology (FIT) is treated only in few studies, but it is pivotal in the eco-manufacturing process. In this paper, we propose a new manufacturing-scenarios-based methodology by using FIT and a Multi-criteria Decision Support Method (MCDSM), which helps manufacturers maintain their marketplaces by producing goods in an eco-friendly way. In fact, this methodology helps designers choose from the CAD design phase the most ecological manufacturing process from possible existent scenarios in real time.     

Layer-wise finite element analysis of functionally graded cylindrical shell under dynamic load

In this paper, a layer-wise finite element formulation is developed for the analysis of a functionally graded material (FGM) cylindrical shell with finite length under dynamic load. For this purpose, FGM cylinder is divided into many sub-layers and then the general layerwise laminate theory is formulated by introducing piecewise continuous approximations through the thickness for each state In this model the radial displacement is approximated linearly through each “mathematical” layer. The properties are controlled by volume fraction that is an exponential function of radius. The governing equations are derived from virtual work statement and solved by finite element method. The main contribution of the present study is to develop a discrete layerwise finite element for a 2-dimensional thick FGM cylindrical shell. Results are obtained for the time history of the displacement and stress components with different exponent “n” of functionally graded material. In addition, natural frequency and mean velocity of the radial wave propagation for different exponent “n” of functionally graded material (FGM) are studied and compared with similar ones currently obtained for FGM cylindrical shell of infinite length.     

Production monitoring—A proven productivity tool

Production executives in modern factories are concerned with standards, real production and schedule maintenance, and with having early foresight into problem areas. The use of digital computers in the factory has for many years been largely divided between “closed-loop control” and “data processing” (DP), but today there is a growing need for “closed-loop information control” (CLIC). This paper describes a system for implementation of this concept using exclusively industry-standard hardware, and its application within smaller industrial operations rather than the industrial giants (although their need may indeed be greater). For many such smaller companies, production monitoring may be a first venture into CIM. Rather than “control” or “data” being the key, “information” is the cornerstone of the system described. The word “information” conjures up a variety of ideas in its normal use, but a visit to a real factory forces a closer look at its meaning, if the CLIC concept is to be even worth considering. Repeatable and verifiable data sources are very difficult to obtain on the factory floor. Physical compatibility is a real concern, because equipment that operates in the usual controlled DP environment is not usually reliable on the factory floor. The operating conditions demanded by much to today's DP equipment preclude heat, vibration, electromagnetic interference and the generally hostile conditions which are prevalent in many factories. Consequently, any factory-floor system is fraught with unique problems all the way from data capture, through communications, into efficient data structures and meaningful graphic presentation. This paper describes such a system and summarises its effect on productivity as proven by application in several factories in the US and Canada.     

Design and static performance of high speed machining centre with “direct drive”

“Direct drive” is an ideal method for speeding machine tools. In the structure of a CNC machining centre with “direct drive”, the linear motor’s primary and secondary parts are assembled into the worktable and machine bed respectively to directly drive the worktable. The built-in rotary motor is assembled in the spindle to realize the main transmission system of the machine tool “direct drive”. All mechanical transmission elements in machine tools are eliminated. High speed, efficiency, and accuracy are easily obtained. However, in this type of “direct drive” machining centre, the magnetic attraction force between the primary and the secondary linear motors and the dynamic impact at acceleration and deceleration are directly imposed on the machine tool, and influence the performance of the machining centre. This paper analyzes the special demands of “direct drive” on the machine centre, and introduces a new structure of the machining tool. The worktable and machine bed are optimized to meet the special demands of “direct drive”. Static performance simulation on the machining centre is done to reveal an ideal result.     

Optoelectronic system for mobile robot navigation

In densely populated cities or indoor environments, limited accessibility to satellites and severe multipath effects significantly decrease the accuracy and reliability of satellite-based positioning systems. To meet the needs of “seamless navigation” in these challenging environments, an advanced terrestrial positioning system is under development. A new principle of mobile robot navigation capable of working in a complex unknown landscape (another planet or just on a cross-country terrain) is proposed. The optoelectrical method proposed has a good spatial domain resolution and immunity to multipath, as well as new optical means for “technical vision” realization. Two related problems are solved: creation of a technical vision system for recognition of images of an unfamiliar landscape and determination of the direction to the initial point of the movement trajectory of the mobile transport robot. Issues of principle design and also of functioning and interaction of system units and elements are described. A mathematical apparatus for processing digital information inside the system and for determining the distances and angle measurements in the system proposed is developed. Some important parameters are analytically determined: expected accuracy, functioning speed, range of action, power issues, etc.     

Continuous path control of a 5-DOF parallel-serial hybrid robot

Using the 5-degree of freedom parallel-serial hybrid robot, to realize the de-burring, new forward and inverse kinematic calculation methods based on the “off-line teaching” method are proposed. This hybrid robot consists of a parallel stage section and a serial stage section. Considering this point, each section is calculated individually. And the continuous path control algorithm of this hybrid robot is proposed. To verify the usefulness, a prototype robot is tested which is controlled based on the proposed methods. This verification includes a positioning test and a pose test. The positioning test evaluates the continuous path of the tool center point. The pose test evaluates the pose on the tool center point. As the result, it is confirmed that this hybrid robot moves correctly using the proposed methods.     

Plant location selection based on fuzzy TOPSIS

The selection of plant location plays a very important role in minimizing cost and maximizing the use of resources for many companies. In this paper, a new TOPSIS approach for selecting plant location under linguistic environments is presented, where the ratings of various alternative locations under various criteria, and the weights of various criteria are assessed in linguistic terms represented by fuzzy numbers. To avoid complicated fuzzy arithmetic operations, the linguistic variables, which are represented by triangular fuzzy numbers, are transformed into crisp numbers based on graded mean representation. The canonical representation of multiplication operations on triangular fuzzy numbers is used to obtain the “positive ideal solution” and the “negative ideal solution”. The closeness efficient is defined to determine the ranking order of all alternatives by calculating the distance to both the “positive-ideal solution” and the “negative-ideal solution” simultaneously. Compared with existing fuzzy TOPSIS methods, the proposed method can deal with group decision-making problems in a more efficient manner. A numerical example of plant location selection is used to illustrate the efficiency of the proposed method.     

A new approach for molding multi component parts

Injection molding has gained an enormous importance over the last twenty years. This is due both to the development of sophisticated products and to the efforts being generally made to the reduction of product weight specially in automobile industry. Developments aimed at creating innovative products are expected to broaden industrial implementation of their techniques. Establishment then requires the progressive development of existing mold techniques and engineering knowledge. This paper describes a successive process for molding multi component complicated products such as door trim, instrument panel and so on. Using an analytical model, the orthogonal experiment method (Taguchi method) and numerical simulation, an optimal process for simultaneous injection molding with “core-back” and “co-injection” technique is presented to produce such innovative products. Through practical tests, this process was verified in terms of applicability.     

Experimental research on thermal comfort in the university classroom of regular semesters in Korea

This research has investigated physical variables affecting indoor thermal comfort and subjective responses of thermal comfort of students in a university in Korea in which the weather is oceanic temperate climate, and has been performed to contribute to the research fields of Sustainable Thermal Standard and Adaptive Thermal Comfort (ATC). This research is based on the ISO 7730-2005 standard and the ATC theories and 4 main variables of PMV such as dry bulb temperature (Ta), relative humidity (RH), black bulb temperature (Tg), and air velocity (Va) are measured once a week during two regular semesters. A clothing insulation, a thermal sensation vote (TSV), an acceptability of thermal environment, and a preference for cooling and heating are investigated at the same time using a questionnaire. This study was carried out for 26 weeks during the spring season, from March to June 2009, and the autumn season, from September to December 2009. The main achievements of this study are as follows. Monthly Mean Outdoor Temperature (MMOT) and Operative Temperature (OT) in the classroom during research periods are 7.4∼23.3°C and 17.5∼29.0°C, respectively. The acceptability ratio of thermal environment shows over 80% when the range of OT in the classroom is 17∼25°C, and the range can be applicable to operative index of heating and cooling of classroom. The mean TSV of respondents is almost “neutral (0)” when the PMV in the classroom moves to “neutral (0)” and “slightly cool (−1)”, and the TSV is almost “+1.5” when the PMV moves to “slightly warm (+1)”. The acceptability ratio of thermal environment is slightly different from ASHRAE Standard 55-2004. So it is necessary to more investigate standard range of acceptability of thermal environment in oceanic temperate climate region using much more databases.     

Intelligent feedback control in CNC ball burnishing operations

A generic “intelligent” feedback system (GIFS) has been developed to optimise the process response in ball-burnishing operations by monitoring and minimising undesirable variations in the machining process variables. The “intelligent” feedback system is software driven, and it has been found that it permits a greater flexibility and control of the operational characteristics of the CNC machine. Also, better and more consistent results can be obtained through this external adaptive-control approach. Experiments conducted on ball burnishing show that improvements in the surface finish (product quality) of between 5% and 17% when this feedback approach is adopted.     

Estimating muscle fatigue of the biceps brachii using high to low band ratio in EMG during isotonic exercise

The principal objective of this study was to estimate biceps brachii muscle fatigue using the fatiguing time (FT) and the initial slope (S_init) of the high to low frequency band ratio (H/LFB) in EMG during isotonic exercise until the endurance time (ET) at which the subject could no longer follow the fixed speed. Surface EMG was measured on the biceps brachii muscle of ten subjects (5 males and 5 females) as the subject performed repetitive elbow contraction tasks. The first task was with no load (“no load” task). The other tasks were performed until exhaustion (“load” task) with a load weighted at 10%, 20% and 30% of the subject’s maximum voluntary contraction (MVC). We extracted decreasing parameters of the EMG, such as median frequency (MDF) and three types of H/LFB (H1; 95∼500Hz, H2; 150∼350Hz, H3; 470∼500Hz and LFB; 15∼45Hz). Statistical analysis was conducted to select an appropriate parameter. The FT was defined as the time at which the selected H/LFB became smaller than the threshold (50% at 10% MVC, 60% at 20% MVC, and 65% at 30% MVC) with respect to the initial value, and S_init was defined as the slope of the linear regression line using H/LFB from the onset of exercise to FT. In order to predict ET, we proposed using an analytical method that employed a multiple linear regression model with two independent variables, FT and S_init. The results from this novel model were compared with those of previously established methods. In the “no load” task, there was no FT in the MDF and three H/LFBs. In the “load” task, the MDF and three H/LFBs gradually decreased, but the H3/LFB decreased most rapidly. A significant difference between the “no load” task and the “load” task at a 95% significant level was only observed in H3/LFB. ETs of all subjects were predicted at an error of approximately 30.4%. This error was better than that obtained using other methods (34.8% by Mathiassen’s method, 39.7% by Ma?setti’s method). FT detected from H3/LFB was a useful indicator to distinguish the EMG in the “load” task from that observed in the “no load” task, and the ET of a subject could be predicted using FT and S_init. Therefore, the H3/LFB provides more information on muscle fatigue than the other features under isotonic conditions, and may be suited to specific experimental protocols in workplace fatigue studies.     

Measurement and Characterization of “Resonance Friction” at High Sliding Speeds in a Model Automotive Wet Clutch

The friction forces between various lubricated “friction materials” and sapphire disks were measured using a new “high-speed” rotating disk attachment to the surface forces apparatus (SFA). Two different clutch lubricants and two different friction materials were tested at sliding speeds and normal loads from 5 to 25 m/s, and 0.2 to 1 N (nominal pressures ~1 MPa), respectively. The results show that “resonance friction”—characterized by large amplitude oscillatory (i.e., sinusoidal) vibrations, also known as shudder or chatter—dominates dynamical considerations at high sliding speed, replacing the smooth sliding or low-amplitude stick–slip that is characteristic of low speed/low load sliding. The characteristic (rotational) speeds or frequencies at which resonance friction occurs depend only on the coupled/uncoupled mechanical resonance frequencies of the loading and friction-sensing mechanisms. In contrast, the intensity of and time to enter/exit shudder depends strongly on the lubricating oil and, to a lesser extent, on the friction material. Physical–chemical analyses of the friction materials before and after testing showed that the samples undergo primarily structural rather than chemical changes. Our results provide new fundamental insights into the resonance friction phenomenon and suggest means for its control.     

A manufacturability advisor for spun and rollformed sheet metal components

In today’s manufacturing scenario, accounting for manufacturability considerations at the product design stage is not an option but a necessity. When CAD/CAM tools are used to reduce design lead times, accounting for manufacturing process related considerations implicitly is often difficult. Availability of manufacturability advisor systems that analyze part geometry and other product related information for ease of manufacturing could be a solution to this problem. The purpose of a manufacturability assessment is to give feedback to the designer in order to make the product/process more effective. Present research is concerned with the development of an automated manufacturability advisor for sheet metal components. Unlike most of the work done in the past that concentrated on bending and other forming processes, present work deals with sheet metal components manufactured by two different processes, namely “spinning” and “rollforming”. Effectiveness of the proposed manufacturability advisor is demonstrated by taking the number of industrial parts as examples.     

Lubrication Mechanisms of Lamellar Fatty Acid Fluids

The lubrication mechanisms of different lamellar fluids are investigated as they are introduced in the thin contact zone between two macroscopic surfaces in motion in a friction measurement set-up. We simultaneously measure the film thickness and its lubricative properties under controlled contact kinematics. The lamellar phases consist of nanometric flat bilayers of fatty acid surfactant molecules organized in periodic stacks separated by a water/ethylene diamine solution. First, we examine the film forming capability of these phases when the two surfaces are moving at the same velocity, i.e. in “pure rolling” conditions. We observe the growth of a thick film in the contact which eventually reaches a stable value. The relatively high viscosity of the film leads to a situation of so-called “starved lubrication”. By modelling the film build-up process, we determine the viscosity of the lubricant and its piezoviscosity. As shear is applied between the surfaces, the lubricant film exhibits a constant thickness and a rather low frictional response. We correlate this behaviour to the combination of a relatively high viscosity value together with a low piezoviscosity. Through the addition of a hydrophobic liquid (naphthenic oil) to the initial system, we increase the bilayer thickness whilst keeping the lamellar characteristic packing distance constant. This changes both the film forming capability and frictional behaviour of the lamellar fluid. We propose a model to account for the observed friction responses of both lamellar phases and discuss the shear localization in the lubricant film.     

Analysis of the HVAC system’s sound quality using the design of experiments

Human hearing is very sensitive to sound, so a subjective index of sound quality is required. Each situation of sound evaluation is composed of Sound Quality (SQ) metrics. When substituting the level of one frequency band, we could not see the tendency of substitution at the whole frequency band during SQ evaluation. In this study, the Design of Experiments (DOE) is used to analyze noise from an automotive Heating, Ventilating, and Air Conditioning (HVAC) system. The frequency domain is divided into 12 equal parts, and each level of the domain is given an increase or decrease due to the change in frequency band based on the “loud” and “sharp” sound of the SQ analyzed. By using DOE, the number of tests is effectively reduced by the number of experiments, and the main result is a solution at each band. SQ in terms of the “loud” and “sharp” sound at each band, the change in band (increase or decrease in sound pressure) or no change in band will have the most effect on the identifiable characteristics of SQ. This will enable us to select the objective frequency band. Through the results obtained, the physical level changes in arbitrary frequency domain sensitivity can be determined.     

Effect of boundary layer swirl on supersonic jet instabilities and thrust

This paper reports the effects of nozzle exit boundary layer swirl on the instability modes of underexpanded supersonic jets emerging from plane rectangular nozzles. The effects of boundary layer swirl at the nozzle exit on thrust and mixing of supersonic rectangular jets are also considered. The previous study was performed with a 30° boundary layer swirl (S=0.41) in a plane rectangular nozzle exit. At this study, a 45° boundary layer swirl (S=1.0) is applied in a plane rectangular nozzle exit. A three-dimensional unsteady compressible Reynolds-Averaged Navier-Stokes code with Baldwin-Lomax and Chien’sk-ε two-equation turbulence models was used for numerical simulation. A shock adaptive grid system was applied to enhance shock resolution. The nozzle aspect ratio used in this study was 5.0, and the fully-expanded jet Mach number was 1.526. The “flapping” and “pumping” oscillations were observed in the jet’s small dimension at frequencies of about 3,900Hz and 7,800Hz, respectively. In the jefs large dimension, “spanwise” oscillations at the same frequency as the small dimension’s “flapping“ oscillations were captured. As reported before with a 30° nozzle exit boundary layer swirl, the induction of 45° swirl to the nozzle exit boundary layer also strongly enhances jet mixing with the reduction of thrust by 10%.     

Implementation of a “backwards planning” technique in the automation of process planning

It is essential to automate the process-planning function to achieve true integration of CAD and NC machining for computer-integrated manufacturing. Several planning techniques have been used for this purpose and the popular method called the “bottom-up” approach or “backwards planning” has been successfully used in developing an expert process-planning system called EXCAP. This paper describes the implementation of this approach, providing details and examples of the model-updating module which enables the planning to be executed automatically for turned components.     

A study of deformation and orientation dependent behavior in single crystals

Deformations of single crystals were studied using finite element analysis to investigate the localized modes and the orientation dependence of plastic deformation observed in single crystals Investigation of mechanical properties of single crystals is closely related with the understanding of deformation processes in single crystals Localized bands such as shear and kink were studied and the material and geometric characteristics that influence the formation of such localized bands were investigated. Orientation dependence of material behavior in NiAl single crystals was studied by rotating slip directions from ‘hard’ orientation The maximum nominal compressed stress in NiAl single ciystals was widely ranged depending on the misalignment from “hard” orientation As the compression axis was set closer to “hard” orientation, the maximum nominal compressed stress was rapidly increased and made <100> slips difficult to activate Therefore, non-<l00> slips will be activated instead of <100> slips for “hard” orientation     

Online qualitative nugget classification by using a linear vector quantization neural network for resistance spot welding

Real-time estimation of weld quality from process data is one of the key objectives in current weld control systems for resistance spot-welding processes. This task can be alleviated if the weld controller is equipped with a voltage sensor in the secondary circuit. Replacing the goal of quantifying the weld quality in terms of button size by the more modest objective of indirect estimation of the class of the weld, e.g., satisfactory (acceptable, “normal” button size), unsatisfactory (undersized, “cold” welds), and defects (“expulsion”), further improves the feasibility of the mission of indirect estimation of the weld quality. This paper proposes an algorithmic framework based on a linear vector quantization (LVQ) neural network for estimation of the button size class based on a small number of dynamic resistance patterns for cold, normal, and expulsion welds that are collected during the stabilization process. Nugget quality classification by using an LVQ network was tested on two types of controllers; medium-frequency direct current (MFDC) with constant current controller and alternating current (AC) with constant heat controller. In order to reduce the dimensionality of the input data vector, different sets of features are extracted from the dynamic resistance profile and are compared by using power of the test criteria. The results from all of these investigations are very promising and are reported here in detail.