Emad Abouel Nasr

A new methodology for extracting manufacturing features from CAD system

In recent years, various researchers have come up with different ways and means to integrate CAD and CAM. Automatic feature recognition from CAD solid systems highly impacts the level of integration. CAD files contain detailed geometric information of a part, which are not suitable for using in the downstream applications such as process planning. Different CAD or geometric modeling packages store the information related to the design in their own databases. Structures of these databases are different from each other. As a result no common or standard structure has been developed so far, that can be used by all CAD packages. For that reason this paper proposes an intelligent feature recognition methodology (IFRM) to develop a feature recognition system which has the ability to communicate with various CAD/CAM systems. The proposed methodology is developed for 3D prismatic parts that are created by using solid modeling package by using CSG technique as a drawing tool. The system takes a neutral file in Initial Graphics Exchange Specification (IGES) format as input and translates the information in the file to manufacturing information. The boundary (B-rep) geometrical information of the part design is then analyzed by a feature recognition program that is created specifically to extract the features from the geometrical information based on a geometric reasoning approach by using object oriented design software which is included in C++ language. A feature recognition algorithm is used to recognize different features of the part such as step, holes, etc. Finally, a sample application description for a workpiece is presented for demonstration purposes.

Engineering Design and Rapid Prototyping

Inevitably, reading is one of the requirements to be undergone. To improve the performance and quality, someone needs to have something new every day. It will suggest you to have more inspirations, then. However, the needs of inspirations will make you searching for some sources. Even from the other people experience, internet, and many books. Books and internet are the recommended media to help you improving your quality and performance.

Computer-Based Design and Manufacturing

This chapter provides an overview of computer-aided design and manufacturing (CAD/CAM), the most important reasons of using CAD systems in the manufacturing environment, computer integrated manufacturing (CIM), the implementation of the automation in the production organization, the role of CAD/CAM systems in the manufacturing facility, the CAM cycle in a feature based design environment, and the different types of features.

Feature Extraction Techniques

This chapter presents a brief review of the previous work on the related topics of feature representation and recognitions. The first section describes previous research efforts in the area of feature representation. Previous research in the area of feature recognition is described in the second section. In third section, a methodology for feature analysis and extraction of prismatic parts for CAM applications is developed and presented. This approach aims to achieve the integration between CAD and CAM.

AN OVERVIEW ON FIVE APPROACHES FOR TRANSLATING CAD DATA INTO MANUFACTURING INFORMATION

All Rapid Prototyping and CNC material removal processes use information which is extracted from a CAD system. There are several ways to convert CAD data into usable manufacturing information. In this paper, five methods of translating CAD data into a usable manufacturing format are explained. These five methods are data translation from CAD files in STL, DXF, STEP-NC, and IGES formats as well as a platform-dependent area method of manufacturing information in a desirable format. For each method, algorithms and details about the CAD data translation into usable manufacturing and prototyping processes formats are presented. Finally, applications of each approach and its pros and cons are summarized in a table.

CAD Issues in Additive Manufacturing

The Additive Manufacturing (AM) process is a computer-controlled process that uses CAD representations to build physical parts layer by layer. Almost all computer-aided design (CAD) packages allow the creation of stereolithography (STL) files, which are translated into machine commands to drive the AM process. Unfortunately, the STL file has many weaknesses and is prone to error. Moreover, there is a need to investigate and understand the issues and errors associated with the software formats and how to control, eliminate, or minimize these errors. Failure to deal with these issues will lead to building poor parts and delayed lead time, which will result in a bad physical model. This chapter summarizes the CAD model of the AM process and explains the various software issues related to the selected CAD representation.

Product design and development framework in collaborative engineering environment

Globalisation has created a situation of increased international competition, which puts companies under pressure to compete in the value added to customers. This paper presents an integrated framework for product design and development in distributed and collaborative environments. The proposed system integrates the software tools and resources in the design process to enable geographically dispersed design teams and vendors to collaborate. The early participation of the vendors in the design process is critical to improve quality and reduce development cycle-time. The real-time, automated generation and modification of parametric CAD models are introduced to further assist the system reduce the cycle-time.

A comparison study on the design of mirror and anatomy reconstruction technique in maxillofacial region

BACKGROUND The customized mandible reconstruction has been a challenging task in maxillofacial surgery. Designing an implant taking into considering the surrounding bone contours is really critical. Various computer aided design techniques have been used in the designing the customized reconstruction implants, but nevertheless study on the comparison between these techniques is rarely used. OBJECTIVE The objective of this study is to compare the mirroring and anatomical reconstruction design techniques used in the maxillofacial surgery and select the best design technique. METHODS The three mandible bone defects-small (< 20 mm), medium (20 to 40 mm) and large (41 to 53 mm) tumors are reconstructed using the two reconstruction design techniques and compared to their accuracy, using a 3 dimensional (3D) implant design evaluation and part to Computer aided design (CAD) comparison using a Co-ordinate measuring machine (CMM). RESULTS The analysis results indicate that the mirroring technique provides higher accuracy for the implant design as compared to the anatomical technique for the medium and large tumors at maxillofacial regions. In case of implant design in small tumors, the anatomical design provides perfect implant fitting. CONCLUSIONS Based on the results, it is recommended to select the anatomy design technique only for small tumor regions and mirroring technique for medium and large tumors.

A comparative study on the customized design of mandibular reconstruction plates using finite element method

Mandible defects and its deformities are serious complications and its precise reconstruction is one of the most challenging tasks in oral maxillofacial surgery. The commercially available standard mandible implants are manually bended before surgery to custom fit the patient’s jaw. A slight mismatch in the plate and bone alignment may result in the implant failure. However, with the integration of computer-aided design, rapid prototyping, and advanced imaging systems (computed tomography or magnetic resonance imaging), it is possible to produce a customized mandible implant that can precisely fit the patient’s jaw. The aim of this article is to compare a new design of customized mandible implant (sinewave plate) and compare it with the commonly used straight implant design. The finite element–simulated results reveal that the commonly used straight reconstruction plates are more prone to loosening of the screws due to its higher strain concentration on the screw hole when compared to newly designed sinewave reconstruction plate. Moreover, the straight plate is more sensitive to the chewing load variations and develops almost 20% increase in the stresses when compared to sinewave plate. The study reveals that the sinewave reconstruction plate can significantly enhance the stability and safety of the mandible implant.

Using data mining in the manufacturing systems for CAD model analysis and classification

The applications of data mining in engineering and manufacturing are enormous and useful for helping in the analysis of large data and information repositories for the discovery of trends, patterns and knowledge. In industrial engineering and manufacturing systems, the data may contain valuable information, or example, in downstream CAM applications such as Computer Aided Process Planning (CAPP). In this paper, we present a new approach for mining large quantities of machining features, Computer-Aided Design (CAD) models and manufacturing data. The approach is based on data mining and uses learning-logic classification techniques for mining 3D CAD data. The proposed approach was evaluated in CAD model analysis, specifically in classification tasks. The experimental results proved that the method is effective in terms of classification accuracy and can be used as an efficient data mining tool for CAD model analysis and classification.