Scheduling optimization of task allocation in integrated manufacturing system based on task decomposition

How to deal with the collaboration between task decomposition and task scheduling is the key problem of the integrated manufacturing system for complex products. With the development of manufacturing technology, we can probe a new way to solve this problem. Firstly, a new method for task granularity quantitative analysis is put forward, which can precisely evaluate the task granularity of complex product cooperation workflow in the integrated manufacturing system, on the above basis; this method is used to guide the coarse-grained task decomposition and recombine the subtasks with low cohesion coefficient. Then, a multi-objective optimieation model and an algorithm are set up for the scheduling optimization of task scheduling. Finally, the application feasibility of the model and algorithm is ultimately validated through an application case study.

Fabrication of polyetheretherketone(PEEK)-based 3D electronics with fine resolution by a hydrophobic treatment assisted hybrid additive manufacturing method

Additive manufacturing(AM)is a free-form technology that shows great potential in the integrated creation of three-dimensional(3D)electronics.However,the fabrication of 3D conformal circuits that fulfill the requirements of high service temperature,high conductivity and high resolution remains a challenge.In this paper,a hybrid AM method combining the fused deposition modeling(FDM)and hydrophobic treatment assisted laser activation metallization(LAM)was proposed for manufacturing the polyetheretherketone(PEEK)-based 3D electronics,by which the conformal copper patterns were deposited on the 3D-printed PEEK parts,and the adhesion between them reached the 5B high level.Moreover,the 3D components could support the thermal cycling test from-55℃ to 125℃ for more than 100 cycles.Particularly,the application of a hydrophobic coating on the FDM-printed PEEK before LAM can promote an ideal catalytic selectivity on its surface,not affected by the inevitable printing borders and pores in the FDM-printed parts,then making the resolution of the electroless plated copper lines improved significantly.In consequence,Cu lines with width and spacing of only60μm and 100μm were obtained on both as-printed and after-polished PEEK substrates.Finally,the potential of this technique to fabricate 3D conformal electronics was demonstrated.

Study on Integrated Quality Assurance System in CIMS

Integrated Quality Assurance System (IQAS) is an important part of CIMS.This paper introduces the architecture of IQAS,elaborates the philosophy of quality assurance and quality control in CIMS.A type of function model is proposed.Meanwhile, details of the model are described.

Analysis of Efficient 32 Bit Adder Using Tree Grafting Technique

Adder with high efficiency and accuracy is the major requirement for electronic circuit design.Here the optical logic gate based adder circuit is designed for better performance analysis of optical input signals varied with the wavelength.Efficiency of the adder can be improved by increasing the speed of operation,reducing the complexity and power consumption.To maintain the high efficiency with accuracy,a new combination of adder has been proposed and tested in this work.A new adder by combining the logics of Brent Kung,Sklansky and Kogge Stone adders by Tree Grafting Technique(BSKTGT)has been tested along with individual Brent Kung,Sklansky,Kogge Stone,Knowles,Han Carlson and Ladner Fischer adders.All the existing and proposed adders have been designed and tested for efficiency with the help of Cadence platform with 45 nm technology.Efficiency in terms of Size reduction,Power reduction,Power Delay Product(PDP)and accuracy in adding 8 bit,16 bit and 32 bit values had been tested for all the adders and found that the 32 bit BSKTGT adder performed well in all aspects and have produced better efficiency with the power consumption of 52.512426μW with 3.16%of power saving over Brent Kung adder,utilised an area of 631.191 with 8.55%reduction over Kogge Stone Adder,has the cell count of 132 which is 10.61%reduction over Brent Kung Adder and PDP value of 122.6695 J,which is 0.46%less than that of the Han Carlson Adder.

Model of Production Planning and Scheduling in Shop Floor Based on Collaboration and Competition

The planning and scheduling in real shop floor is actually achieved by coordination between different persons. In this process, cooperation is mainstream, but competition also exists, for example, the competition between different groups, operators with the same skill, etc. In multi-agent based shop floor management and control system, this competition and cooperation relation must be embodied. The general process of shop floor production planning and scheduling is studied, and a colored Petri-net model for the competition and cooperation process of three main agents in such system to achieve shop floor production planning and scheduling is presented. The evaluating method of bids in bidding process that especially embodies the competition relationship is also presented. This colored Petri-net model gives a clear illustration of this complex coordination process to system designers, effectively promotes the cooperative development.

A Control System of Material Handlingin FMS

The design of a control system for the material transport as used in gear-box flexible manufacturing system is presented in this paper. The scope of investigation covers material transport control, automatic vehicle, material exchange station, multi-storeyed warehouse system, NC and CNC machines and host computer etc. The paper describes the transport control system and its design, and briefly describes the communication among devices and warehouse access principles.

Prospects of Robot Laser Cutting in the Era of Industry 4.0

Laser cutting is a non-contact thermal cutting process and an integral part of manufacturing. In metal processing, laser cutting is at the forefront of the manufacturing chain followed by joining and manufacturing processes like welding. The future of metal manufacturing processes like laser cutting shall rely on intelligent systems such as automation and robotics based on the advancement of technology and digital transformation spearheaded by Industry 4.0. Moreover, the digital transition where robots and automated systems are key drivers creates a broader platform to utilize energy-efficiency materials. Such energy-efficient materials include high-strength steels (HSS) for structural applications (e.g. bio-energy structures, wind turbines, ice-going vessels) onshore, offshore and in the Arctic region. The aim of this paper is to elucidate the prospects of robot laser cutting systems in the framework of integrated metal manufacturing in future factories. Previous studies on laser cutting technologies are examined based on scientific and industrial perspectives. Robot laser cutting system is compared with the well-known flat-bed laser cutting CNC machine in several aspects including flexibility in manufacturing, ease for digitalization, off-line capabilities and investment analysis. The findings shall help to determine the competitiveness of robot laser cutting systems with flat-bed laser cutting CNC machines, especially when considering metal manufacturing in small and medium-sized enterprises (SMEs). The outcome of this study is to stir up experimental and computational research on robot laser cutting systems of metals, and help companies in their decision-making process when deciding which laser cutting system will best suit their manufacturing operations in the future.

Current researches on design and manufacture of biopolymer-based osteochondral biomimetic scaffolds

Currently,osteochondral(OC)tissue engineering has become a potential treatment strategy in repairing chondral lesions and early osteoarthritis due to the limited self-healing ability of cartilage.However,it is still challenging to ensure the integrity,physiological function and regeneration ability of stratified OC scaffolds in clinical application.Biomimetic OC scaffolds are attractive to overcome the above problems because of their similar biological and mechanical properties with native OC tissue.As a consequence,the researches on biomimetic design to achieve the tissue function of each layer,and additive manufacture(AM)to accomplish composition switch and ultrastructure of personalized OC scaffolds have made a remarkable progress.In this review,the design methods of biomaterial and structure as well as computer-aided design,and performance prediction of biopolymer-based OC scaffolds are presented;then,the characteristics and limitations of AM technologies and the integrated manufacture schemes in OC tissue engineering are summarized;finally,the novel biomaterials and techniques and the inevitable trends of multifunctional bio-manufacturing system are discussed for further optimizing production of tissue engineering OC scaffolds.

THCAPP: Computer Aided Process Planning System in an Integrated Environment

THCAPP is a computer aided process planning system for non-rotational parts which runs in a CIMS (computer integrated manufacturing system ) environment at Tsinghua University. Its architecture is described in this paper. Then its main functions and key techniques, including part modeling, generative process planning and integration with CAD (computer aided design) and CAM (computer aided manufacturing) ale discussed in detail.

Advances and challenges on springback control for creep age forming of aluminum alloy

Creep age forming(CAF)is an advanced forming technology that combines creep deformation and age hardening processes.When compared with the conventional forming technologies including roll bending and shot-peen forming,CAF has many advantages of low residual stress,excellent dimensional stability,good service performance and short production cycle.It is an optimal technique for precise manufacturing for shape and properties of large-scale complicated thinwalled components of light-weight and high strength aluminum alloys in the aviation and aerospace industries.Nevertheless,CAF has an inevitable disadvantage that a large amount of springback occurs after unloading,which brings a challenge on the accurate shape forming and property tailoring of components.Therefore,how to achieve accurate prediction and control of springback has always been a bottleneck hindering the development of CAF to more industrial applications.After the factors of affecting springback and measures of reducing springback are summarized from the internal and external aspects,constitutive models for predicting springback and springback compensation methods for CAF of aluminum alloy panel components are reviewed.Then,a review of research progresses on tool design for CAF is presented.Finally,in view of the key issue that it is difficult to predict and control the shape and properties of components during CAF,the technical challenges are discussed and future development trends of CAF are prospected.

Metallurgical concepts for optimized processing and properties of carburizing steel

Carburized steel grades are widely used in applications where high surface near hardness is required in combination with good core toughness as well as high strength and fatigue resistance. The process of carburizing lower to medium carbon containing steel can generally provide this combination of properties and has been prac- ticed for several decades. Such steel is essential in the vehicle power-train, machines and power generation equipment. However, the increasing performance demands by such applications as well as economical considerations forced steel producers to develop better alloys and fabri- cators to design more efficient manufacturing processes. The present paper describes recent concepts for alloy design optimization of carburizing steel and demonstrates the forthcoming beneficial consequences with regard to manufacturing processes and final properties.

Machining Robot with Vibrational Motion and 3D Printer-like Data Interface

In this paper, a vibration motion control is proposed and implemented on a foamed polystyrene machining robot to suppress the generation of undesirable cusp marks, and the basic performance of the controller is verified through machining experiments of foamed polystyrene. Then, a 3 dimensional （3D） printer-like data interface is proposed for the machining robot. The 3D data inter- face enables to control the machining robot directly using stereolithography （STL） data without conducting any computer-aided man- ufacturing （CAM） process. This is done by developing a robotic preprocessor that helps to remove the need for the conventional CAM process by directly converting the STL data into cutter location source data called cutter location （CL） or cutter location source （CLS） data. The STL is a file format proposed by 3D systems, and recently is supported by many computer aided design （CAD）/CAM soft- waxes. The STL is widely used for rapid prototyping with a 3D printer which is a typical additive manufacturing system. The STL deals with a triangular representation of a curved surface geometry. The developed 3D printer-like data interface allows to directly control the machining robot through a zigzag path, rectangular spiral path and circular spiral path generated according to the information included in STL data. The effectiveness and usefulness of the developed system are demonstrated through actual machining experiments.

Current State and Development Trends for Integration Platforms

The integration platform (IP) is an advanced support tool for application software development and integration. This paper analyzes the shortcomings of traditional software programming methods, introduces the background and development of integration platforms and presents the basic functions and system architecture of computer integrated manufacture computing environment (CCE) IP as well as the integration framework. Computer integrated manufacturing system (CIMS) application IP is defined in relation to the IP requirements for CIMS implementation within a company. The CIMS application IP is not only a support tool for application software development, but also a support tool for software integration and system operation. Therefore, the behavior and functions of a CIMS application IP must also include software integration and system operation. The development trend for CIMS application Ips is discussed in view of software technology development trends.

CORBA Based CIMS Application Integration

Common object request broker architecture (CORBA) provides the framework and the mechanism for distributed object operation. It can also be applied to computer integrated manufacturing system (CIMS) application integration. This paper studies the CIMS information service requirement, presents a CORBA based integration approach including the CORBA based CIM information system architecture and the application integration mechanism, and discusses the relationship between CORBA and the CIM application integration platform.

Integrating EMIS in CIMS

Enterprise management information system (EMIS) in Manufacturing CIMS Integrating Platform (MACIP), refers to a computer system that manages the information for running an enterprise. A typical EMIS consists of a group of closely connected functions such as production planning, material management, accounting, quality management, etc. The EMIS exchanges information with the CAD/CAPP system in the design department, and the shop floor controller (SFC) in the manufacturing department, while the global information system (GIS) of MACIP supplies the mechanism for information sharing within the enterprise. This paper introduces the EMIS model for a typical manufacturing enterprise, then analyses the interface of the EMIS with the CAD/CAPP system and the SFC. A technical scheme for integrating the EMIS with the GIS is given. This scheme considers the integration of some MRPII systems in the market, and adopts advanced industrial standards to ensure its flexibility and reusability.

Communication System for CIMS Application Integration Platform

IMS has seen the growth of multiple incompatible hardware architectures, each architecture supporting several incompatible operating systems, and each platform operating with various incompatible development tools (e.g., programming language compilers, DBMS, etc.) and one or more incompatible graphic user interfaces. Also, the growth of the Internet, the World Wide Web, has introduced new dimensions of complexity into the development process. All of these must be dealt with as the application is made workable in a distributed client server environment. This paper outlines the architecture of a communication system for the CIMS application integration platform. The communication system makes possible the request for service across heterogeneous platforms and networks, and provides some common solutions to issues common to CIMS applications.

STEP AP 242 Managed Model-based 3D Engineering:An Application Towards the Automation of Fixture Planning

Fixture design and planning is one of the most important manufacturing activities, playing a pivotal role in deciding the lead time for product development. Fixture design, which affects the part-quality in terms of geometric accuracy and surface finish, can be enhanced by using the product manufacturing information(PMI) stored in the neutral standard for the exchange of product model data(STEP) file, thereby integrating design and manufacturing. The present paper proposes a unique fixture design approach, to extract the geometry information from STEP application protocol(AP) 242 files of computer aided design(CAD) models, for providing automatic suggestions of locator positions and clamping surfaces. Automatic feature extraction software "FiXplan", developed using the programming language C#, is used to extract the part feature, dimension and geometry information. The information from the STEP AP 242 file is deduced using geometric reasoning techniques, which in turn is utilized for fixture planning. The developed software is observed to be adept in identifying the primary, secondary, and tertiary locating faces and locator position configurations of prismatic components. Structural analysis of the prismatic part under different locator positions was performed using commercial finite element method software, ABAQUS, and the optimized locator position was identified on the basis of minimum deformation of the workpiece.The area-ratio(base locator enclosed area(%)/work piece base area(%)) for the ideal locator configuration was observed as 33%. Experiments were conducted on a prismatic workpiece using a specially designed fixture, for different locator configurations. The surface roughness and waviness of the machined surfaces were analysed using an Alicona non-contact optical profilometer. The best surface characteristics were obtained for the surface machined under the ideal locator positions having an area-ratio of 33%, thus validating the predicted numerical results. The efficiency, capability and applicability of the developed software is demonstrated for the finishing operation of a sensor cover – a typical prismatic component having applications in the naval industry, under different locator configurations.The best results were obtained under the proposed ideal locator configuration of area-ratio 33%.

Modeling and Analysis of Capacitated Transfer Lines with Unreliable Machines and Deterministic Procesing Times

This paper presents an efficient method of equivalient workstations for modeling and analysis of multistage transfer lines with unreliable machines and finites buffers. The deterministic processing times for discrete parts and random failuse and repair times for machines are assumed. These buffers lead to blockage and starvation in operation due to limited storage capacities and make the problem of modelling and analysis very difficult to treat because they have large state spaces and cannot be decomposed exactly. A single buffer between two reliable workstations is analysed first. Then an equivalent workstation without starvation and blockage is constructed. Thereafter connecting all the equivalent workstations in series we get the equivalent transfer line. A set of preformance measures such as the production rates, efficiencies and average inventory levels are derived in explicit analytical expressions. Finally two numerical examples are given for comparing these calculated results with those of S. B. Gershwin (1987) and C. R. Glasseye & Y. Hong (1993) and illustrating the application of the method in engineering design directly.

Implementation of WPDL Conforming Workflow Model

Workflow process definition language (WPDL) facilitates the transfer of workflow process definitions between separate workflow products. However, much work is still needed to transfer the specific workflow model to a WPDL conforming model. CIMFlow is a workflow management system developed by the National CIMS Engineering Research Center. This paper discusses the methods by which the CIMFlow model conforms to the WPDL meta-model and the differences between the WPDL meta-model and the CIMFlow model. Some improvements are proposed for the WPDL specification. Finally, the mapping and translating methods between the entities and attributes are given for the two models. The proposed methods and improvements are valuable as a reference for other mapping applications and the WPDL specification.