Simultaneous engineering for self-directed work teams implementation: A case study in the electronics industry

Simultaneous engineering is based on the interaction between different disciplines and parallel consideration of design with production. This is usually taken as embracing product design and the manufacturing process (for instance in design for manufacturability), or product, manufacturing process and maintenance strategies (in design for maintainability) etc. A simultaneous engineering approach can also be of great value, however, for work organisation change, and vice versa. This paper describes a case study where problems with the product design and manufacturing process meant that these were redesigned in parallel with the implementation of self-directed work teams. In fact, the involvement of the first pilot team in this redesign enabled them to gain much of the confidence, skills and knowledge they required to operate successfully, and early decisions on the form and management of the team structure were supported.

Relevance to industry

Team work is an increasingly common choice of manufacturing and other companies to organise their production and assembly activities. The case study in this paper illustrates lessons in implementation of self-directed work teams. Moreover, it is emphasised that such implementation can be a fundamental part of simultaneous engineering, and also that teams themselves can contribute to concurrent product and process development.     

Geometric reasoning for mill-turn machining process planning

An integrated system to support both product and manufacturing process design should be such that (1) the part design can be evaluated and redesigned based on manufacturability analysis and (2) the manufacturing processes can be selected efficiently and flexibly exploiting product information provided by part design representations.

In this paper, we describe the feature-based geometric reasoning system for part modeling and process planning as applied to mill-turn machined parts. The feature recognition system based on convex decomposition and the mapping method to relate the negative feature volumes to machining process classes are applied to mill-turn parts. Also, the geometry-based machining precedence relations have been generated for various alternative machining feature decompositions. The above geometric information is input to mill-turn machining process planning to determine machining process sequences and assignment to multiple spindles and turrets.     

Manufacturing evaluation using resource-based, template-free features

This paper addresses the theory and tools that promote rapid product and process development of machined products. A foundation of this approach is the application of a new definition of manufacturing features called resource-based free-form features. Using free-form features we demonstrate how cost, time and quality predictions, based on available equipment, are computed. We also introduce the concept of intelligently clustering alternative features to achieve better process alternatives. The approach presented herein is appropriate throughout the product design life-cycle as an aid to faster product realization by evaluating the parochial manufacturability of a completed design. In particular, this approach will provide the design team with cost, time and quality predictions, based on available equipment, that can be used to guide the design process. It also provides the manufacturing team with an approach to evaluating producibility and generating a production plan for a product model using available equipment in terms of cost, time and quality.     

Feature-based modeling for automatic mesh generation

Automatic meshing algorithms for finite element analysis are based on a computer understanding of the geometry of the part to be discretized. Current mesh generators understand the part as either a boundary representation, an octree, or a point set. A higher-level understanding of the part can be achieved by associating engineering significance and engineering data, such as loading and boundary conditions, with generic shapes in the part. This technique, called feature-based modeling, is a popular approach to integrating computer-aided design (CAD) and computer-aided manufacturing through the use of machinable shapes in the CAD model. It would seem that feature-based design also could aid in the finite element mesh generation process by making engineering information explicit in the model.This paper describes an approach to feature-based mesh generation. The feature representation of a fully functioning feature-based system that does automatic process planning and inspection was extended to include finite element mesh generation. This approach is based on a single feature representation that can be used for design, finite element analysis, process planning, and inspection of prismatic parts. The paper describes several advantages that features provide to the meshing process, such as improved point sets and a convenient method of simplifying the geometry of the model. Also discussed are possible extensions to features to enhance the finite element meshing process.     

Automating manufacturability evaluation in CAD systems through expert systems approaches

Design for Manufacturability (DFM) represents a new awareness of the importance of product design as an integral part of manufacturing activities. Good design guidelines exist in industry for frequently used manufacturing processes. These guidelines are systematic statements of good design practices, empirically derived over years of design and manufacturing experience. Ensuring that the given product design conforms to each of the guidelines specific to the selected process results in better manufacturability. To meet the objectives of the DFM approach, design and manufacturing planning activities have to be combined into a single engineering effort and applied througout the life cycle of a product. Computer-aided design (CAD) systems offer powerful features such as the ability to develop complex solid models and perform engineering analyses, including stress analysis, interobject interference, collision detection, and inertial analysis. However, a prominent limitation faced by designers in CAD systems is the lack of “intelligence.” Though designs could be developed, analyzed, and perfected from a functional viewpoint in CAD systems, manufacturability consideration may get little or no attention at all. As a result, product designs that are functionally sound may be developed at a high manufacturing cost. Thus, intelligence should be incorporated in CAD systems, whereby product designs could not only be developed and analyzed but also evaluated for cost and manufacturability. This study attempts to perform this task automatically in a CAD system using a knowledge-based approach: the manufacturability criteria are considered for milling and drilling operations performed on a computerized numerically controlled (CNC) milling machine. The results obtained from the application of the expert system suggest that the expert systems methodology is a feasible method for implementing manufacturability evaluation capability in CAD systems.     

Knowledge-based manufacturability assessment: an object-oriented approach

To help the achievement of integrated product and process development, there is a need for tools that can assist designers in creating manufacturable parts with less design routines and tryouts. This paper presents a systematic approach to developing automated manufacturability assessment tools by identifying the functional and informational requirements and proposing an assessment model. The work presented in this paper includes: (1) identification of characteristics and tasks of design for the die-casting process; (2) determination of functional and informational requirements for automatic manufacturability assessment; (3) formalization and modularization of assessment knowledge; and (4) modeling of product definition data to support the assessment. Object-oriented techniques are employed to model the assessment knowledge and manage the complicated and diverse types of product definition data by taking advantage of data abstraction, modularity, inherent concurrence, and the concept of encapsulation and extendibility.     

A general model for machinable features and its application to machinability evaluation of mechanical parts

This paper is intended to reveal the rationale in the machinability evaluation and to present an effective, systematic approach to the assessment of the machined parts in the early stage of design. By examining the inherent shaping mechanism of machining processes, a geometric feature model, termed ‘machining volume’, resulting from the cutter's movement that mimics the cutter's real motion trajectory in machining, is proposed with which a set of feature derivatives can be affiliated. The geometric and topological patterns of machining volume permit to capture and convey machinability constraints on a part shape, leading to a new, simple machinability evaluation method centered on machining volume. This method is dedicated to two kinds of inspection on the geometry of a part in design: one is to search for unmachinable surfaces that are beyond the capability of machining processes, and the other to detect machining interference between a cutter and a part. It shows a more useful means to characterize machinable features that result in the machinability evaluation with ease and efficiency.     

A novel methodology of design for Additive Manufacturing applied to Additive Laser Manufacturing process

Nowadays, due to rapid prototyping processes improvements, a functional metal part can be built directly by Additive Manufacturing. It is now accepted that these new processes can increase productivity while enabling a mass and cost reduction and an increase of the parts functionality. However, the physical phenomena that occur during these processes have a strong impact on the quality of the produced parts. Especially, because the manufacturing paths used to produce the parts lead these physical phenomena, it is essential to considerate them right from the parts design stage. In this context, a new numerical chain based on a new design for Additive Manufacturing (DFAM) methodology is proposed in this paper, the new DFAM methodology being detailed; both design requirements and manufacturing specificities are taken into account. The corresponding numerical tools are detailed in the particular case of thin-walled metal parts manufactured by an Additive Laser Manufacturing (ALM) process.     

Automation in the design of EDM electrodes

Plastic parts, especially those designed for consumer electronics products, are becoming more compact and freeform in shape. This requires the construction of compact and delicate geometric features in the injection moulds that produce these parts. It is now common practice to employ electric discharge machining (EDM) whenever the conventional machining process fails to machine such delicate features. Although CAD/CAM systems are widely used in mould design and manufacturing, and specific commercial CAD/CAM systems that are customized for injection mould applications are also available, there are still no intelligent CAD tools that address the specific requirements of EDM electrode design. The aim of this research is to develop an intelligent CAD tool that supports EDM electrode design. This CAD tool uses a new technique that recursively splits the EDM region into sub-regions until machinable electrodes can be constructed. The CAD tool has been implemented and integrated into a commercial CAD/CAM system, and 40 different real designs has been used to test its capability in handling a wide variety of geometric shapes. Performance data show that the efficiency of the design process can be improved by at least 50%, with a potential to achieve 85% through improved implementation and further research.     

A new DFM approach to combine machining and additive manufacturing

Design for manufacturing (DFM) approaches aim to integrate manufacturability aspects during the design stage. Most of DFM approaches usually consider only one manufacturing process, but product competitiveness may be improved by designing hybrid modular products, in which products are seen as 3-D puzzles with modules realized individually by the best manufacturing process and further gathered. A new DFM system is created in order to give quantitative information during the product design stage of which modules will benefit in being machined and which ones will advantageously be realized by an additive process (such as Selective Laser Sintering or laser deposition). A methodology for a manufacturability evaluation in case of a subtractive or an additive manufacturing process is developed and implemented in a CAD software. Tests are carried out on industrial products from automotive industry.     

Domain independent shell for DfM and its application to sheet metal forming and injection molding

The objective for this research is to streamline design for manufacturing (DfM) analysis across all manufacturing domains and to provide transparency for DfM measures and evaluation process used. Generic steps are identified for performing manufacturability analysis and the design of a customizable manufacturability evaluation shell is presented. The shell covers several stages of manufacturability analysis (technical, economic) and can perform analyses at different levels of abstraction (qualitative, quantitative). The shell provides feedback to the designer at each level during the design process. By separating domain-specific knowledge from domain independent knowledge and creating an open architecture, the shell can be customized and expanded by the knowledge engineer and the user. The architecture of the shell is presented and its applications to manufacturability analysis for two domains, sheet metal and injection molding, are illustrated.     

Conceptual design, manufacturability evaluation and preliminary process planning using function-form relationships in stamped metal parts

A large number of design decisions are made during the conceptual design of a part. However, there are few representation and reasoning tools for decision support during conceptual design. The conceptual design stage is characterized by a lack of complete geometric information. Existing geometric modelers require complete geometric information, while a functional reasoning methodology using a <verb, noun > representation is typically too terse. In this paper, we present a new representation called sketching abstraction for conceptual design, using the function-form relations in a design. The functionally critical part of the geometry is presented using a set of functional features, while the rest of the geometry is abstracted as a set of linkages. Part functionality is correlated with the sketching abstraction using data structures called function-form matrices. The sketching abstraction is annotated using a set of primitives, and a set of grammar rules are used to extract canonical relationships between the functional features. The sketching abstraction can be used for extracting designs that are geometrically dissimilar but functionally similar, thus providing the designer with ideas for design alternatives. The sketching abstraction can also be used to carry out domain-dependent manufacturability evaluation checks. A further use of sketching abstractions is to initiate the development of a process plan for manufacturing. Sketching abstractions are related to the solid model of a part. Thus, this representation provides a link between pure functional and pure geometric representations. The domain of application is stamped metal parts. We present the part functionality and the features used in this domain. We also illustrate the use of sketching abstractions for conceptual design, manufacturability evaluation and preliminary process planning.     

基于深度学习的孔特征可制造性分析方法

针对传统基于知识库及规则库的零件可制造性分析方法柔性差,以及现有基于深度学习的可制造性分析方法无法给出零件具体不可制造原因的现状,提出一种基于深度学习的零件可制造性分析方法.首先,通过数字化建模技术构建大量带有具体可制造性类别标签的三维CAD模型,并进行点云提取,从而构建深度学习所需数据集;然后,基于PointNet网...     

A knowledge-based approach to design for manufacturability

In the light of growing global competition, organizations around the world today are constantly under pressure to produce high-quality products at an economical price. The integration of design and manufacturing activities into one common engineering effort has been recognized as a key strategy for survival and growth. Design for manufacturability (DFM) is an approach to design that fosters the simultaneous involvement of product design and process design. The implementation of the DFM approach requires the collaboration of both the design and manufacturing functions within an organization. Many reasons can be cited for the inability to implement the DFM approach effectively, including: lack of interdisciplinary expertise of designers; inflexibility in organizational structure, which hinders interaction between design and manufacturing functions; lack of manufacturing cost information at the design phase; and absence of integrated engineering effort intended to maximize functional and manufacturability objectives. The purpose of this research is to show how expert systems methodology could be used to provide manufacturability expertise during the design phase of a product. An object- and rule-based expert system has been developed that has the capability: (1) to make process selection decisions based on a set of design and production parameters to achieve cost-effective manufacture; and (2) to estimate manufacturing cost based on the identified processes. The expertise for primary process selection is developed for casting and forging processes. The specialized processes considered are die casting, investment casting, sand casting, precision forging, open die forging and conventional die forging. The processes considered for secondary process selection are end milling and drilling. The cost estimation expertise is developed for the die casting process, the milling and drilling operations, and the manual assembly operations. The results obtained from the application of the expert system suggest that the use of expert systems methodology is a feasible method for implementing the DFM approach.     

A sensing strategy for the reverse engineering of machined parts

The reverse engineering of machined parts requires sensing an existing part and producing a design (and perhaps a manufacturing process) for it. We have developed a reverse engineering system that has proven effective with a set of machined parts. This paper describes the system, presents some results, and discusses strategy for a new system.This work was supported by ARPA under ARO grant number DAAH04-93-G-0420, DARPA grant N00014-91-J-4123, NSF grant CDA 9024721, and a University of Utah Research Committee grant. All opinions, findings, conclusions or recommendations expressed in this document are those of the authors and do not necessarily reflect the views of the sponsoring agencies.     

Inspection of the machined surfaces using manufacturing data

Accuracy of complex machined parts is usually estimated using coordinate measurement machines. The inspection results can be used to control or monitor a production system. Traditional inspection process of a machined surface commonly compares the resulting manufactured surface with the CAD-model or the nominal designed surface. Although, the result of this CAD-based inspection can be used to accept or reject the machined part, it does not provide the correct information required to study the machining errors and their behaviour. This paper presents a methodology to inspect a machined surface directly based on its actual CAM geometric model. The presented CAM-based inspection methodology can be used to model and understand the real machining errors, which can be utilized for process control, design for manufacturing or closed-loop machining.     

Logic programming for process planning in the domain of sheet metal forming with progressive dies

In this work an intelligent system pertaining to sheet metal part and process design has been developed, storing knowledge and prescribing ways to use this knowledge according to the ‘programming in logic’ paradigm. The sheet metal parts covered by the software are those having U shape and being manufactured by bending (folding), cutting and piercing with particular emphasis on progressive dies. The use envisaged and corresponding parts of the system are: checking the part design for manufacturability, planning process phases, and checking the configuration of press tools involved. Particular attention is paid to the presentation of knowledge that has been gathered from handbooks and verified / enhanced in industry. This is first presented in natural language and then its formal representation in Prolog is described and explained by examples. Part design and press tool checking knowledge is relatively straightforward to represent and structure ‘linearly’. Process planning knowledge is based on patterns that are captured in lists and activated in a case-by-case fashion exploiting the power of Prolog. Validation of the system was conducted using examples from industry.     

A design methodology for configuration of manufacturing cells

This paper presents a general design methodology for manufacturing cells. The approach makes use of the observation that 85% of the production demand of a manufacturing facility can be attributed to 15% of the products manufactured in the facility. This logic was extended to manufacturing cell design. Specifically, within a part family, those parts that have a high steady demand should be placed in cells that are configured and operated similar to a flow line. Those part numbers within the family that have little demand should be assigned to cells designed to operate more as a job shop. In this way, a manufacturing cell that is designed to serve both the high and low demand components will not be impeded by imposed constraints resulting from demand or processing time considerations for individual parts within the family. The author presents a ten step approach for analysis and design of such cells after initial machine-component groupings have been formed.     

改进的精密机械加工零件表面缺陷检测算法

对加工表面纹理缺陷进行可靠的检测分析可以有效提高机械加工零件表面精加工的水平。基于计算机视觉技术对机械加工零件表面实现自动缺陷检测,由于机械加工零件表面纹理的特殊性,常用的灰度图像分割方法对机械加工零件表面缺陷的检测不适用;且其表面的缺陷信息无法预先得知,其图像分割是一个非监督纹理分割问题,对此提出了一种改进的模糊聚类缺陷检测算法,实现了对机械加工零件表面缺陷的自动化检测,实验结果证明了该算法的可行性。