Review of research in feature-based design

Research in feature-based design is reviewed. Feature-based design is regarded as a key factor towards CAD/CAPP integration from a process planning point of view. From a design point of view, feature-based design offers possibilities for supporting the design process better than current CAD systems do. The evolution of feature definitions is briefly discussed. Features and their role in the design process and as representatives of design-objects and design-object knowledge are discussed. The main research issues related to feature-based design are outlined. These are: feature representation, features and tolerances, feature validation, multiple viewpoints towards features, features and standardization, and features and languages. An overview of some academic feature-based design systems is provided. Future research issues in feature-based design are outlined. The conclusion is that feature-based design is still in its infancy, and that more research is needed for a better support of the design process and better integration with manufacturing, although major advances have already been made

From CAD and RP to innovative manufacturing

From CAD and Virtual Prototyping, there are already available many Rapid Prototyping (RP) techniques to produce physical, hand hold able parts. A brief overview is presented of some important aspects regarding how to get a good 3D solid model, how to transfer it to RP machines and how to produce quickly a physical prototype. The RP models could be used for different downstream applications. The paper gives some alternative tooling routes, depending on some criteria, such as: volume production, material and complexity of the parts. The RP models could be used as master models for vacuum casting, metal spraying, investment casting and other innovative manufacturing techniques

Accessing 3D Data

The issue of access and discoverability is not simply a matter of permissions and availability. To identify, locate, retrieve, and reuse 3D materials requires consideration of a multiplicity of content types, as well as community and financial investment to resolve challenges related to usability, interoperability, sustainability, and equity. This chapter will cover modes, audiences, assets and decision points, technology requirements, and limitations impacting access, as well as providing recommendations for next steps

A Case Study for Financial Feasibility of Automated Costing Support in A Small Machine Shop

A knowledge-based cost estimating expert system is chosen by a Mexican machine shop. Differences between the traditional experience-based system employed and the automated system are studied. Data is gathered to analyze time effectiveness, accuracy and payback of the software. Data from seventy part models is recorded to study the time experiment, and data from fifty part models is used to study the accuracy and consistency. Data is analyzed by calculating mean, standard deviation, and test of hypothesis. The results indicate that the software is faster than the traditional quoting system; however, the payback point is high. Also, results show the software has a smaller average time-to-manufacture percentage difference between the automated system and the actual time-to-manufacture (TTM) compared to the percentage difference between the traditional’s TTM and actual TTMs, and this difference is statistically significant. The standard deviation for the automated system is also less implying better consistency

System-Layout-Dependent Thermally Induced Solder Stress & Reliability Implications

Electronic flip chip assemblies consist of dissimilar component materials, which exhibit different CTE. Under thermal cyclic operating conditions, this CTE mismatch produces interfacial and interconnect stresses, which are highly dependent on system layout. In this paper, sensitivity analyses are performed using ANSYS FEA to establish how the proximity and arrangement of neighboring devices affect interconnect stress. Flip chip alignment modes ranging from edge-to-edge to corner-to-corner are studied. Results of these FEA studies, demonstrated that closely packing devices together has the effect of making them act as one. This results in a significant increase in the thermomechanical stresses induced on peripheral solder joints, heightening reliability risk. The sensitivity subsides gradually as device spacing increases, and eventually stops being a factor. 6mm is the threshold separation at which this occurs, in both edge-edge and corner-corner placement, for the system under analysis in this paper. Understanding the effect of system layout is instrumental for optimizing system design and improving reliability of power modules to meet the increasing power density needs

Definition of a system to extract hot gas from an entrained flow gasifier

This project work covers the design and construction of a new probe system for hot gas analysis in an entrained flow gasifier. The aim is a probe that can be used more flexibly than the present system. As a further aim, the condensation of trace materials has to be prevented. First, a short overview over current techniques to analyse the product gas in a gasification process is given. Continuing, the report describes the finding and assessing of several possible principles of hot gas extraction from a gasification process using simulations in ANSYS Fluent. The best performing design based on defined trace component condensation is built for a verification experiment and tested under controlled conditions in a tube furnace. Verification experiments comprise temperature measurements and analysis of retrieved samples via x-ray induced fluorescence. Temperature measurements show that the planned effect of mixture cooling is exceeded by far by convective cooling of the probe. Although simulations were promising, the approach is not applicable under current operating conditions due to problems with the measurement system. Furthermore, the amount of condensed trace material in the retrieved samples proves not to be sufficient for quantitative analysis via x-ray fluorescence. An alternative system to retrieve hot gas while maintaining it at high temperatures out of the gasifier is then modeled