This paper is aim to develop and investigate a permanent magnet linear-motor-driven table system for a wire-EDM machine. Dynamic model and system identification of the linear motor system have been derived and analyzed. The linear motor drive system has nonlinear and time-varying behaviors because of the effect of irregular friction of the sliding surface and cogging force. Therefore, a conventional digital controller may not suffice to provide a high contouring accuracy as well as adequate disturbance rejection and parameter variation robustness. An indirect adaptive controller (IAC), combined with a neural network-based feedforward controller (NNBFC) is proposed to improve contouring performance of the linear motor system. Experimental results show that this control method achieves satisfactory contouring accuracy under the influence of friction and cogging force.
In this paper, we propose a flow shop scheduling problem with no-wait flexible lot streaming. The problem involves the splitting of order quantities of different products into sublets and the consideration of alternative machines with different processing times. Sublets of a particular product are not allowed to intermingle, that is sublets of different products must be no-preemptive. The objective of the problem is the minimization of makespan. An adaptive genetic algorithm is proposed which is composed of three main steps: first step is a position-based crossover of products and four kinds of local search-based mutations to generate better generations. Second step is an iterative hill-climbing to improve the current generation. The last step is the adaptive regulation of crossover and mutation rates. Experimental results are presented for various sizes of problems to describe the performance of the proposed four local search-based mutations in adaptive algorithm.
A fuzzy interpolation method is proposed to simplify the calibration process for parallel machine tools. Either inverse or forward kinematic models need to be used in the traditional calibration methods to perform the identification and compensation of the pose errors for parallel machine tools. Instead of using a model, the proposed method presents a modeless technique combined with the fuzzy interpolation method to obtain the same or higher calibration accuracy when a small workspace is adopted.
This paper presents a systematic approach for automatic assembly sequence planning (ASP) by using an integrated framework of assembly relational model (ARM) and assembly process model (APM), which are established by object-oriented method. ARM, consisting of assembly, components and liaisons, is used to describe the geometric relationships between components in terms of contact, constraint and interference matrixes. And APM, containing states and sub-processes, is to represent all potential alternatives in assembly process. An algorithmic procedure is also presented, by which APM of an assembly can be constructed systematically by analysing states from lower levels to higher levels. Through the procedure, all feasible sequences of a product can be generated, and the optimum one can be determined by further evaluating each sequence. To explain the approach, a sample assembly with 4 components is always used throughout the paper.
A newly-developed knowledge-based diagnosis system for automobile engines is described in this paper. The system is based on the Hierarchical Diagnosis Principle, suggested by the authors. According to this principle, a complex diagnostic task can be divided into several simple ones and then solved step-by-step. Both deep and shallow knowledge are used in the system, and organised in two different knowledge bases:
⊙ A static knowledge base, which uses frames to describe the structure, symptom and fault information of the system to be diagnosed;
⊙ A dynamic knowledge base, which uses production rules and special functions to describe various dynamic information for diagnosing the locations and causes of a system fault.
The system employs a hierarchical and modular architecture which has two levels: a meta-level and an object-level. The knowledge base of the object-level system, according to the fault types and structure hierarchy of the system to be diagnosed, is divided into several independent knowledge sources which are controlled by the meta-level system. The knowledge sources communicate with each other through a working memory called a ‘blackboard’.
The cast extrusion manufacturing process is the initial step which enables the creation of the raw materials, such as clear polypropylene film, needed for the flexible packaging manufacturing process. The current methodology of controlling extrusion related defect occurrences is attempted by a combination of statistical sampling and human inspection. However, the defects are small in size and hard to visualise in a clear thin film 3 m in width moving at a speed of 50 m/min. This resulted in poor product quality and high return ratio from customers. To the best of our knowledge, there is no system available that can automatically and accurately detect such defects. This research investigates possible defect detection methodologies and has subsequently proposed a system that is capable of real time monitoring of defects on the cast extrusion manufacturing process.
This paper presents a study on three types of finite element analyses of high power ultrasonic transducer by using the finite element commercial software called ANSYS. The transducer geometry was treated as a 2D axi-symmetric model, 3D quart and full 3D model. For all of the simulations the modeled transducer was used in modal analysis and harmonic solutions to understand its mechanical behavior and its natural frequency. A comparison was made between each type of modeling and experimental results. This comparison allows the parameters of FEM models to be iteratively adjusted and optimized and also leads to selection of the best modeling type. The achieved FEM results exhibited a remarkably high predictive potential of ANSYS in modeling and simulation and allowed control on the design and on the vibration behavior of the high power ultrasonic transducer.
Most of the studies of quality system or product-quality assessment deal with a single quality characteristic to determine the quality loss. Products are often assessed on more than one quality characteristic. For this reason, different multivariate quality loss functions have been proposed. However, these loss functions only consider the nominal-the-best quality characteristics (N-type); they do not consider the condition when the quality characteristics are of the smaller-the-better (S-type). In this article, we present a quality evaluation model using loss function for multiple S-type quality characteristics. A numerical example is illustrated showing that using inappropriate loss functions will lead to inaccurate results that give either an underestimate or overestimate of the expected quality costs.
Advanced creep-resistant steels have been developed to meet the demanding requirements of fossil power plants that strive
to improve the generation efficiency by enhancing the steam temperature and pressure. These are ferritic steels with nominal
chromium content ranging from 2% to 12% with significant addition of tungsten besides Nb, V, and N in small level. One of
the candidate materials is 9Cr-0.5Mo-1.7W steel, developed for steam circuit components of tubes, and pipes of power plants
for an operating temperature of 600°C. Hydrogen cracking is a major issue in welding of this steel, due to solid-state metallurgical
transformations that lead to untempered martensite in the HAZ of weld joint. The hydrogen cracking does not occur below a
threshold stress level called critical cracking stress. The critical stress for cracking in this steel was determined by carrying
out implant weldability tests using shielded metal arc welding process for various levels of diffusible hydrogen in the weld
metal and an empirical model relating levels of diffusible hydrogen and time taken for cooling from 800°C to 500°C to the
critical stress has been developed. Results of current study also showed that residual diffusible hydrogen plays a major role
in deciding hydrogen cracking than the initial diffusible hydrogen in the weld metal.
KeywordsHydrogen cracking-Advanced creep-resistant steels-Critical stress-Steels-Implant test-Welding
Industry has put forward demands on cross enterprises collaboration including various resources sharing. In order to meet
these demands, much has been done to realize cross-border collaboration. However, after analyzing the unique features of manufacturing
resources and the limits of existing technologies like Internet, EC, ASP and Web-based design/manufacturing, which adopt many
new Web technologies like Web mark-up languages, Web-based client–server programming tools and distributed object modeling
methods, it is concluded that all these technologies could not meet industrial demands on dynamic sharing of various resources.
Therefore grid manufacturing is put forward to meet these demands. According to the features of resources to be shared and
the technologies to be used, grid manufacturing distinguishes itself from Web-based manufacturing by providing the transient
services and by achieving the interoperability. The differences and relationship between grid manufacturing and grid computing
are yielded. At last, a Web service-based architecture of grid manufacturing is proposed and the related technologies are
The concept of manufacturing grid (MGrid) is to utilize manufacturing resources distributed in heterogeneous systems and different
places to collaboratively manufacture products the market requires. The solution is based on adopting grid technologies, information
technologies, advanced manufacturing technologies, management technologies, etc., to realize the complete sharing of all kinds
of geographically distributed and heterogeneous manufacturing resources in the form of virtual enterprises. After summarizing
the grid technology and its applications, we propose the concept of MGrid. The application of grid technology in manufacturing
and the related works about MGrid are investigated. The connotation of MGrid are put forward, including its basic features,
the structure and main functions, the main research contents, the architecture, and key technologies. A resource service optimal-selection
system of MGrid and its main functions are researched, including resource service description, resource service publication,
resource service discovery, resource service quality of service (QoS) evaluation, and resource service optimal-selection evaluation.
An application prototype, namely magnetic bearing resources sharing and service platform under manufacturing grid, is developed.
It validates the resource service sharing and optimal-selection system in MGrid.
Current research on manufacturing grid (MGrid) systems has mainly concentrated on its concept, architecture, application prototype
platform, and application foreground. Absent from the trend is the quality of service (QoS) of MGrid, such as QoS modeling,
QoS evaluation, and QoS-based scheduling, which play a very important role in MGrid resource management. The related topics
about MGrid and QoS are investigated in this study. The characteristics of QoS associated with its management requirements
in MGrid are then further studied. Classification and modeling of MGrid QoS are investigated from three different perspectives:
QoS whole-lifecycle management, MGrid architecture view, and QoS attribute parameters. The measurement and evaluation models
of QoS parameters in MGrid are presented. A simple case study is described to illustrate how the proposed works can be applied
to MGrid resource service management.
In the present investigation, tests were conducted on a tribological couple made of cylindrical lead pin with spherical tip
against 080 M40 steel plates of different textures with varying roughness under both dry and lubricated conditions using an
inclined pin-on-plate sliding tester. Surface roughness parameters of the steel plates were measured using optical profilometer.
The morphologies of the worn surfaces of the pins and the formation of transfer layer on the counter surfaces were observed
using a scanning electron microscope. It was observed that the coefficient of friction and the formation of transfer layer
depend primarily on the surface texture of hard surfaces. A newly formulated non-dimensional hybrid roughness parameter called
‘ξ’ (a product of number of peaks and maximum profile peak height) of the tool surface plays an important role in determining
the frictional behaviour of the surfaces studied. The effect of surfaces texture on coefficient of friction was attributed
to the variation of plowing component of friction, which in turn depends on the roughness parameter ‘ξ’.
In this paper, we present a literature review, classification schemes and a simple meta-analysis for scheduling of batch processors
(SBP) research in semiconductor manufacturing (SM). This review is based on a study of journals and web-based documents/articles,
which include conference materials, lecture notes in computer science, working papers, etc. There are 98 articles published
in various publication outlets between 1986 and October 2004. Based on the literature review carried out and the nature of
SBP research observed in SM, we have introduced two classification schemes to systematically organize the published articles.
The first classification scheme is based on the problem configurations of SBP research in SM and the second one is based on
the solution methodology followed by the researchers. These classification schemes indicate that there is much research scope
on SBP research in SM. Furthermore, a simple meta-analysis is carried out to enhance understanding on the development and
evolution of SBP research in SM and to identify potential research areas for further research and for improvement. The results
show that there is an increasing trend in SBP research in SM. A comprehensive list of references is presented. This study
is expected to provide a source of reference for other researchers (or readers), who are interested in SBP research particularly
in SM and help stimulate further interest.
The process of material cutting and fracture by high velocity water jets is a complex series of phenomena which may involve
compression, tension, shear, erosion, wears, cracking, wave propagation, and cavitations damage. This makes the exact analysis
of the jet cutting process to be very complicated. The problem of water jet coal cutting is a multiresponse problem. There
are two output variables, depth of cut and cutting width whose optimization will result in the increase in the productivity
of coal cutting. In this paper, a Taguchi–Fuzzy decision method has been used to determine the effective process parameters
for improving the productivity of coal mines. The Taguchi method of experimental design is a widely accepted technique used
for producing high quality products at low cost. The optimization of multiple responses in complex processes is common; therefore,
to reduce the degree of uncertainty during the decision making, fuzzy rule-based reasoning was integrated with the Taguchi
KeywordsWater jet–Coal cutting–Taguchi techniques–Fuzzy logic–Productivity
The aim of this study is to analyze the evolution of surface roughness finished by burnishing. Burnishing is done on a surface that was initially turned or turned and then ground. In a previous work, we have defined an analytical model to determine the Rt factor of burnished surfaces in relation to the feed f, the material displacement δ and the roughness Rti of the initial surface. δ has been calculated using the Hertz contact theory which supposes that the behavior of the workpiece material is elastic. Hence, in this paper, we have defined a finite element model in which the elasto-plastic behavior of the piece is taken into account to determine the material displacement δ. This model has also permitted the calculation of the residual stresses related to the macroscopic contact geometry. Good correlations have been found between experimental and finite element results when burnishing an AISI 1042 steel.
The aim of this study is to analyse the evolution of surface roughness finished by burnishing. Burnishing is done on a surface that was initially turned or turned and then ground.
It has been noted that burnishing an AISI 1042 steel offers the best surface quality when using a small feed value. This finishing process improves roughness and introduces compressive residual stresses in the machined surface. So, it can replace grinding in the machining range of the piece.
Also, an analytical model has been defined to determine the R
factor in relation to the feed. Good correlations have been found between the experimental and analytical results.
Modeling and optimization of cutting parameters are one of the most important elements in machining processes. The present
study focused on the influence machining parameters on the surface roughness obtained in drilling of AISI 1045. The matrices
of test conditions consisted of cutting speed, feed rate, and cutting environment. A mathematical prediction model of the
surface roughness was developed using response surface methodology (RSM). The effects of drilling parameters on the surface
roughness were evaluated and optimum machining conditions for minimizing the surface roughness were determined using RSM and
genetic algorithm. As a result, the predicted and measured values were quite close, which indicates that the developed model
can be effectively used to predict the surface roughness. The given model could be utilized to select the level of drilling
parameters. A noticeable saving in machining time and product cost can be obtained by using this model.
KeywordsResponse surface methodology–Genetic algorithm–Box-Behnken design of experiments–Minimum quantity lubricant–Drilling–Surface roughness
Shot peening is widely used to improve the fatigue properties of components and structures. Residual stresses, surface roughness,
and work hardening are the main beneficial effects induced in the surface layer from shot peening, which depend on the correct
choice of the peening parameters. In this investigation, experiments were designed using the full factorial design of experiment
(DOE) technique and an air blast type of shot peening machine. Effects of process parameters such as pressure, shot size,
stand-off distance, and exposure time on surface microhardness for AISI 1045 and 316L materials were investigated. An ANOVA
was carried out to identify the significant peening parameters. In the case of 316L material, the maximum surface hardness
was found to be in the range of 450–824Hv, whereas it was found to be in the range of 314–360Hv for AISI 1045. A critical
assessment was made so as to understand the variation of microhardness in the direction of peening. Empirical equations between
the peening parameters and the surface microhardness for both materials were developed, which are useful in predicting the
surface microhardness. It is believed that this technique could prove beneficial in industries for reduction of performance
variation and cost and to increase productivity.
The aim of the present study was to investigate the effects of investment casting and forging process on the microstructure
and mechanical properties of friction weldments, AISI 1050–AISI 304. A continuous-drive friction welding device with the automatic
control ability of friction time and forging pressure was designed and constructed. Factorial design of experiments was performed
to join investment cast AISI 1050 steels and forged AISI 1050 steels with AISI 304 austenitic stainless steel with respect
to the optimized process parameters. The joint performance was evaluated by tensile and hardness tests performed parallel
and perpendicular to the weld interface. Microstructure of forged parts under friction welding was examined using optical
microscopy, scanning electron microscopy, and energy-dispersive spectroscopy. Results of microstructural studies were compared
with those of friction welding of investment cast parts. The results reveal that a recrystallized region or a mechanically
mixed layer was formed on the AISI 304 side near the weld interface, depending on friction time and friction pressure. Friction
welding of forged parts always exhibited higher tensile strength, lower hardness, and more upset than the cast parts.
In this study, the effect of friction-stir welding (FSW) parameters such as spindle rotational speed, traverse speed, and
stirrer geometry on mechanical properties of AA 1050/AA 5083 alloy couples were experimentally investigated. Ultimate tensile
strength (UTS) and hardness of welded joints were determined for this purpose. The full-factorial experimental design was
conducted to obtain the response measurements. Analysis of variance (ANOVA) and main effect plot were used to determine the
significant parameters and set the optimal level for each parameter. A linear regression equation was derived to predict each
output characteristic. The experimental and predicted values were in a good agreement with a R
2 of 0.82 and 0.93 for UTS and hardness, respectively.
The micro-electrical discharge machining (micro-EDM) process has proved to be an appropriate nonconventional machining method
for manufacturing accurate and complex three-dimensional structural micro-features which are difficult to be produced by conventional
processes. However, the miniaturisation of the EDM process requests special requirements on the machining equipment. Pulse
generators which can produce small input energy pulses and high precision systems are the two major requirements. In this
paper, newly developed technologies regarding these aspects are explored with the aid of a commercial micro-EDM machine. By
examining the pulses, innovative strategies implemented in the pulse generator are studied. Pulse measurements reveal the
correlation between the discharge pulses and the machine parameters in order to provide an overview of process capability.
Conclusions are applied on machining of a ceramic composite Si3N4-TiN and optimised machining settings for different machining conditions are achieved. Accordingly, applications of two- and
three-dimensional micro-structures on different types of materials such as a stainless steel micro-compressor and a ceramic
miniature gas turbine are demonstrated. By inspecting the machining geometry and surface integrity, process characteristics
of micro-EDM are discussed.
KeywordsMicro-EDM-Ceramic composite-3D EDM milling
Grinding is one of the major machining processes of gem manufacturing. The largest gemstone in the jewelry market is the cubic
zirconia (CZ) which is ground in the same fashion as diamonds. This study was interested to investigate the influence of parameters
on grinding CZ gemstone. The parameters were grinding speed, depth of grinding, and abrasive grit size of diamond electroplated
disc. The results could conclude that the surface finish was improved when increasing grinding speeds and abrasive grit size.
The grinding time was decreased with an increase in grinding speeds. Examination of the surface texture of the ground surface
on CZ was analyzed and reported.
In precipitation hardenable materials, it is desirable to determine the precipitate dissolution temperature for homogenizing
the microstructure by controlling the size and distribution of the precipitates. In this research, the influence of various
heat treatment and hot deformation conditions on the kinetics of γ′ dissolution and its morphological evolution in Nimonic 115 was studied. In addition, hot deformation behavior of the material
was investigated using hot compression experiments at varying temperature (between 1,050°C and 1,175°C) and strain rates (between
0.01 and 1s−1) up to a true strain of 0.8. The values obtained for the solvus temperature of γ′ precipitates by two methods are all in agreement indicating this temperature at approximately 1,165 ± 5°C. Through examination
of the influence of temperature and strain rate on the hot deformation behavior, it was determined that the experimental flow
stress observations could be effectively related to the processing parameters using an Arrhenius relationship. The results
indicate that dynamic recrystallization is the main softening mechanism during the high temperature deformation of Nimonic
115, and it can be effectively promoted by increasing the deformation temperature. By deformation at temperatures higher than
1,125°C, a completely recrystallized microstructure is obtained.
The paper presents a survey of five-axis computer numerical controlled (CNC) machining optimization methods employing adaptable geometric patterns. First, the survey introduces evolution of CNC interpolators from the simplest Taylor series-based routines to sophisticated procedures based on constraint minimization from dynamic systems control theory. Furthermore, a variety of methods based on spline interpolation, NURBS interpolation and Farouki's Pythagorean-hodograph curves is presented and analyzed. Next, the survey deals with techniques to optimize the positions and orientations of the tool in a particular neighborhood of the part surface. The most important application of these techniques is cutting by a flat-end or a fillet mill while avoiding local overcuts or undercuts due to the curvature interference and rear gouging. This section is supplemented by detection of global interference using visibility cone schemes and their recent modifications and improvements. Solutions offered by solid modeling are presented as well. Finally, adaptable geometric patterns employed for tool path generation are considered and analyzed. The adaptation is performed using certain criteria of the tool path quality, such as kinematics error, scallops, possible undercuts or overcuts, and the continuity of the path. Also covered are complex pocket milling employing geometric patterns capable of following the boundary, such as the offset methods, regional milling, the potential path methods, and clustering. The chapter also presents tool path optimization based on the adaptable curvilinear grids connecting the cutter location points. Finally, navigation approaches and the shortest-path schemes are considered, along with the adaptive spacefilling curve algorithms and their combinations with grid generation.