Flattening and Foaming

Q.1 Write a one page report on what is Neutral Data File? What does it mean? Where it is used?

Neutral Data File is one of the three options of CAD data exchange. so, let me first explain what is CAD data exchange.

CAD Data Exchange:-

CAD data exchange is a modality of data exchange used to translate data between different computer-aided design(CAD) authoring systems or between CAD and other downstream CAx systems.

Many companies use different CAD systems internally and exchange CAD data with suppliers, customers and subcontractors. Transfer of data is necessary so that, for example, one organization can be developing a CAD model, while another performs analysis work on the same model; at the same time a third organization is responsible for manufacturing the product.

The CAD systems currently available in the market differ not only in their application aims, user interfaces and performance levels, but also in data structures and data formats therefore accuracy in the data exchange process is of paramount importance and robust exchange mechanisms are needed.

The exchange process targets primarily the geometric information of the CAD data but it can also target other aspects such as metadata, knowledge, manufacturing information, tolerances and assembly structure.

There are three options available for CAD data exchange: direct model translation, neutral file exchange and third-party translators.

Now we know what is CAD Data Exchange, so lets try and understand more about Neutral Data File.

Neutral Data File:-

Neutral file exchange uses an intermediary neutral format to translate data between CAD systems. This method starts from a pre-processor embedded in the original CAD system, which generates the neutral file from the originating CAD format. The target CAD system post-processes the neutral file and converts it into the target native format. Some neutral formats are defined by standards organisations such as IGES and STEP while others are proprietary but still widely used and are regarded as quasi industry standards.

Neutral formats

• IGES(Initial Graphics Exchange Specification) – originated in late 1979 and initially published by the American National Standards Institute (ANSI) in 1980 preceding the large-scale deployment of the CAD technology in the industry. This file format considers the product definition as a file of entities, with each entity being represented in an application-independent format. After the initial release of STEP (ISO 10303) in 1994, interest in further development of IGES declined, and Version 5.3 (1996) was the last published standard.
• DXF(Drawing eXchange format) – developed by Autodesk in 1982 as their data interoperability solution between AutoCAD and other CAD systems. The DXF is primarily 2D-based and its format is a tagged data representation of all the information contained in an AutoCAD drawing file, which means that each data element in the file is preceded by an integer number that is called a group code indicating the type of following data element. As most commercial application software developers have chosen to support Autodesk's native DWG as the format for AutoCAD data interoperability, DXF has become less useful.
• VDA-FS(Verband der Automobilindustrie – Flächenschnittstelle) – created by the German Association of the Automotive Industry in 1982 as an interoperability method for free-form surfaces. This format differs from other formats in that it only supports the communication of free-form curve and surface data with associated comments, but no other geometric or non-geometric entities. Therefore, it is limited to representations by parametric polynomials, but this covers the great majority of free-form CAD systems. It includes Bezier, B-Spline and Coons tensor product types of surfaces and corresponding curves. The VDA-FS specification is released in the German Industrial Standard DIN 66301.
• PDES (Product Data Exchange Specification) – originated in 1988 under the Product Definition Data Interface (PDDI) study done by McDonnell Aircraft Corporation on behalf of the U.S. Air Force. PDES was designed to completely define a product for all applications over its expected life cycle, including geometry, topology, tolerances, relationships, attributes, and features necessary to completely define a part or assembly of parts. PDES can be viewed as an expansion of IGES where organizational and technological data have been added. In fact, the later PDES contained IGES. The development of PDES under the guidance of the IGES organization and in close collaboration with the International Organization of Standardization (ISO) led to the birth of STEP.
• STEP(ISO 10303 – Standard for the Exchange of product model data) – the work with the ISO 10303 standard was initiated in 1984 and initially published in 1994, with the objective to standardize the exchange of product data between PLM systems. It is a very comprehensive set of specifications covering many different product types and many life cycle phases. STEP uses the neutral ISO 10303-11 format, also known as an EXPRESS schema. EXPRESS defines not only the data types but also relations and rules applying to them. STEP supports data exchange, data sharing and data archiving. For data exchange, STEP defines the transitory form of the product data that is to be transferred between a pair of applications. It supports data sharing by providing access to and operation on a single copy of the same product data by more than one application, potentially simultaneously. STEP may also be used to support the development of the archive product data itself. STEP consists of several hundred documents called parts. Every year new parts are added or new revisions of older parts are released. This makes STEP the biggest standard within ISO. The 200-series parts STEP are called Application Protocols (AP), with the specific parts directly related to CAD systems:
  • 203 (Configuration controlled 3D designs of mechanical parts and assemblies) – Mainly used for 3D design and product structure. A subset of AP214 but most widely used.
  • 210 (Electronic assembly, interconnect and packaging design) – CAD systems for printed circuit board.
  • 212 (Electrotechnical design and installation) – CAD systems for electrical installation and cable harness.
  • 214 (Core data for automotive mechanical design processes) – How STEP is represented in a text file for interchange.
  • 238 (STEP-NC Application interpreted model for computerized numerical controllers) – CAD, CAM, and CNC machining process information.
  • 242 (Managed model based 3D engineering) – the merging of the two leading STEP application protocols, AP 203 and AP 214.
• parasolid XT – part of the Parasolid geometric modeling kernel originally developed by Shape Data and currently owned by Siemens PLM Software. Parasolid can represent wireframe, surface, solid, cellular and general non-manifold models. It stores topological and geometric information defining the shape of models in transmitting files. These files have a published format so that applications can have access to Parasolid models without necessarily using the Parasolid kernel. Parasolid is capable of accepting data from other modeler formats. Its unique tolerant modeling functionality can accommodate and compensate for less accurate data.

By using Neutral Data File we can eliminate the problem of plenty number of translators, and reduce it to only one translator by implementing a menthod of neutral file.

fig. Data exchange using Neutral File

When this neutral file is used, each CAD system needs only one preprocessor and one postprocessor which form one set of translators. Figure 3 illustrates the way the pre-processor imports the data into the system and the post-processor outputs the file into standard.

fig. CAD Data Exchange

Q.2 Create the report in continuation with the report created under challenge-7 (Bracket-II) add the flattening and forming.

Title:- Flattening and Foaming

Objective:-

To create a flattening bracket using NX CAD.

Introduction:-

For Flattening the Bracket. i have used some NX Cad tools.

Tools which has been used are Flattening and Foaming, Thicken

Design methodology:-

• Import Neutral Data File
• Use Flattening and Foaming for Flattening the bracket
• Use Thicken to give some thickness to the flattened bracket.

Description:-

Neutral data File:-

It is the data file which can be used as a excahnge medium between different CAD systems.

Flattening and Foaming:-

It is used to flatten profile by specifying faces to flatten, origin of surfaces, primary direction of the surface.

Thicken:-

By using Thicken we can give the desired offset to the flattened profile.

Screenshots:-

Conclusion:-

Thus, we have successfully Flattened the Bracket-II using NX Cad.

Part file:- https://drive.google.com/open?id=1gIe27nl87sP5pfai_pb1Zi-j29BT9xhf