Some Geometric Techniques to Reduce Build Time in LOM

We propose a new CAPP system for the layered manufacturing technology of LOM (laminated object manufacturing). The traditional technique of building wastes much effort and time in generation of rectangular grid patterns to the exterior of the model to facilitate waste removal. In the proposed approach, several geometric properties of the model are exploited to dramatically reduce the waste removal grids. This in turn leads to reduced build-time, with no effect on the build quality. An integrated CAPP system incorporating these ideas has been developed, and an example part is presented to show how the system performs.

Greedy Tool Heuristic for Rough Milling of Complex Pockets

The milling of complex pockets bounded by NURBS surfaces is usually broken into rough and finish milling, with the former taking up the bulk of the machining time. This time can be reduced if the proper combination of end-mills of different sizes are used to machine in different regions. The greedy tool heuristic presented in this paper is a new approach for determination of the machining volume that should be allocated to different tools selected from among a large set of available tools. Subsequent machining planning can then be performed by repeated application of standard 2D milling algorithms. This new approach in multiple-tool rough milling of complex shapes promises to reduce machining time of parts with complex shapes, such as modern moulds and casting patterns.

Analytical Method for Mapping Function to Failure During High-Risk Component Development

Communicating failure mode information during design and manufacturing is a crucial task for failure prevention. Most processes use Failure Modes and Effects types of analyses, as well as prior knowledge and experience, to determine the potential modes of failures a product might encounter during its lifetime. When new products are being considered and designed, this knowledge and information is expanded upon to help designers extrapolate based on their similarity with existing products and the potential design tradeoffs. This paper makes use of similarities and tradeoffs that exist between different failure modes based on the functionality of each component/product. In this light, a function-failure method is developed to help the design of new products with solutions for functions that eliminate or reduce the potential of a failure mode. The method is applied to a simplified rotating machinery example in this paper, and is proposed as a means to account for helicopter failure modes during design and production, addressing stringent safety and performance requirements for NASA applications.

Process Planning in Layer-Based Machining

Some freeform surfaces cannot be machined by traditional CNC machining because of the inaccessibility to some critical points. Layer-based machining system developed by the authors can enlarge the accessibility by building a model layer by layer. Each layer is shaped by 5-axis machining. In this paper, the overall process planning techniques are identified and analyzed. The data flow chart in layer-based machining is established. The concepts of “decomposition for accessibility” and “decomposition for manufacturability” are proposed to decompose the model into manufacturable parts, which is called slabs. Adaptive slicing and interference avoidance algorithms are developed to achieve the maximum accessibility. A method called stock layer combination is proposed to select available stock layers for the process.

Comprehensive Satisfactory Design Method for Product Designs

Actual product designs aim to fulfill all product requirements of market needs and wants, which are technical or non-technical, logical or illogical, objective or subjective, and quantitative or qualitative. The actual product designs are objective-aiming designs and can be supposed to be multi-objective satisfactory designs with heterogeneous objective functions and dimensional design variables. To realize computer-aided product designs which can obtain rational and satisfactory solutions, we classify the objective functions and contrive methods to deal with non-theoretical, non-technical, subjective, or illogical objective functions as well. This paper shows all of our methods, including an expression of heterogeneous objective functions which consists of objective and evaluated values, a satisfactory design method by simultaneous equations which searches solutions sequentially, identification methods of non-theoretical or non-technical objective functions and sensitivity coefficients for the simultaneous equations, a decision-making method of promising solutions to fulfill product requirements, and also numerical applications of these methods to actual product designs.

Integrating Market Research With the Product Development Process: A Step Towards Design for Profit

This paper describes a systematic approach for integrating market research with the product development process. The following three problems are addressed in this paper. First, a demand estimation algorithm has been developed based on conjoint measurement techniques. Second, an integrated design decision model has been developed. The main components of this design decision model are representation of available design options using AND/OR tree based representation, and an evaluation procedure for evaluating profit resulting from a design option. Third, a heuristic search technique has been developed that makes use of the design decision model to select the design option that maximizes the profit. Integration of market research with the product development process is expected to result in the following two benefits. First, it will reduce the number of design iterations. Second, it will help the design team in finding the most profitable product designs.

Visualization of Milling Processes on Internet

In current environment of simultaneous product development, the Internet is being recognized as the best platform for implementation of virtual manufacturing organization located at different global places. This paper represents a step towards the integration of product development teams and introduces a novel method for visualization of manufacturing processes in order to verify the process plans generated. The paper presents the pilot implementation in VRML with JavaScript as a scripting language for dynamic nature of the program. Using the concepts of Geometric representation of the Manufacturing processes a program in C++ language is developed, which supplies data for animation. The results are presented on Internet by developing a web page for Visualization of Manufacturing Processes.

Strategic Decisions in the Early Stages of Product Family Design

The realization that designing products in families can and does have significant technological and economic advantages over traditional single product design has motivated increasing interest in recent years in formal design tools and methodologies for product family design. However, currently there is no guidance for designers in the first key strategic decisions of product family design, in particular determining the type of product family to design. Hence in this paper, first a taxonomy of different types of product families is presented which consists of seven types of product families, categorized based on number of products and time of product introduction. Next a methodology is introduced to aid designers in determining which type of product family is appropriate, based upon early knowledge about the nature of the intended product(s) and their intended market(s). From this information it also follows both which manufacturing paradigm and which fundamental design strategies are appropriate for the product family. Finally the proposed methodology is illustrated through a case study examining a family of whitewater kayaks.

Operation Ordering Principles and Intra-Setup Planner: Combining Human Control With Automation in Process Planning

We present in this paper 1) operation ordering principles and 2) a customizable process planner, Intra-Setup Planner that implements those principles. The principles and the planner focus on sequencing cutting operations within individual setups for three and five axis prismatic milling applications. There is no general agreement on ordering principles largely because different shops have very different needs. To address a wide range of users’ needs, we have designed both the ordering principles and the Intra-Setup Planner to support flexibility rather than providing a single one-size-fits-all prescription for operation ordering. The Intra-Setup Planner provides a convenient user interface, Rule Editor through which users can select the ordering principles that suit their own situation, an automated planner that will follow the user selected principles, and a Plan Editor to allow final adjustments. The combination of flexible principles and user control maximize the strengths of human and machine intelligence.

Automatic Setup Planning and Operation Sequencing for Satisfying Tolerance Requirements

In this paper, a novel approach to automatic setup planning and operation sequencing of a part is proposed. The critical tolerance feature sets of the part are first identified by comparing the tolerance specifications with the capabilities of machine tools. Then, based on the concepts of critical tolerance feature set, the feature model of the part is decomposed into a series of identical setup feature (ISF) sets, each of which corresponds to a setup candidate. Finally, according to geometric precedence and tolerance precedence among features, the reasonable machining operations of features with multiple machining operations are determined, the ISF sets are sequenced and merged. Compared to previous work, the approach can generate the setup plan by which the part can be machined to satisfy the required tolerances. The approach also has high efficiency.