Apart from increasing the productivity of designers and improving the quality of design, computer-aided design (CAD) software assist in the creation, analysis, modification or optimisation of a design. The major areas where CAD is used are electronic design, mechanical design and engineering drawings. Here is an overview of this software
VariCAD is a software for 3D/2D CAD that runs on Windows and Linux. In addition to tools for 3D modelling and 2D drawing-cum-editing, it provides support for geometrical constraints, tools for shells, pipelines, sheet metal unbending and crash tests, and assembly support to name a few. The system contains both 3D and 2D libraries of mechanical parts (DIN and ANSI), hydraulic and electrical symbols, and tolerance symbols as well.
VariCAD features a lot of interesting functions that vary from an intuitive user interface (UI) all the way to performing virtual crash tests and creating a bill of materials (BOM).
User interface and system environment. Designed to allow quick and intuitive 3D/2D orientation, VariCAD’s graphical user interface has been carefully tailored and tuned to reflect the thought process of a designer so that ideas can be captured and communicated with a minimal number of steps. The commands have been created with a focus on ease of use.
It is possible to start by creating a 3D model and then use it to automatically create drawing files, or draw only in 2D. Designing in 3D is generally more natural since it closely represents actual parts and assemblies. Hence the 3D approach is usually more intuitive than 2D drafting. Models created in 3D can be easily converted into conventional 2D documentation.
3D modelling. With the help of a library of basic 3D shapes (box, cylinder, cone, etc) that could be easily modified by editing their dimensions, solids can also be created by profile rotation, lofting or extrusion. Tools with higher complexity include rotation blending between two profiles, creation of helical surfaces, and lofting between a circle and rectangle, or between different profiles.
Addition or subtraction of solids is possible, thus forming Boolean trees representing real mechanical parts. Automatic trimming is available for Boolean operations. Predefined operations like groove milling, face milling or drilling of holes are also available. With an option of rounded or chamfered edges, VariCAD provides a lot of possibilities of solid transformations or their editing. Also, Boolean trees can be easily edited by selecting them from a list displaying the structure, or by selecting solid parts from 3D.
Parameters and geometrical constraints. Solids or their parts can be comfortably transformed, and it is also possible to optionally define geometrical constraints. Once defined, these constraints allow the user to ‘stick’ object at the defined location. Constrained object changes its position automatically if other objects are changed or transformed. For example, if a user constrains a groove to the end of a shaft and the length of the shaft is changed, the groove remains in constant distance from the end edge. Constraints can be defined within a 2D profile creating a solid (for instance, by extrusion), among elements of a solid or among entire solids.
Whenever the user enters a dimension in 2D profile used for solid creation, a distance in constraint or a dimension of solid, it is possible to optionally use parameter or even a mathematical expression containing parameters. One can change shapes or locations of solids by changing parameter values.
3D assemblies and groups. VariCAD also provides assembly support tools. If the link between a part and assembly is defined, any changes to be made to the part file are reflected in the assembly file and vice-versa. Linked copies of solids (also known as identical solids) can also be defined.
When creating assemblies, it is up to the user whether he wants to use links between the assembly and parts or have all-in-one document. If you decide to use these links, all the changes in assemblies or parts are automatically made also in all the drawings you need.
Crash tests (interferences). Component interference checking is one of the excellent features of 3D modeling. VariCAD can check 3D assemblies for possible collisions (overlapping volume) between components.
Calculations. Moment of inertia, centre of gravity, mass, volume, 2D section area and surface area can be calculated with the help of VariCAD. Mechanical parts calculations are also included for standard parts used everyday by mechanical designers. There are calculations of belt drives, pre-stressed bolted connections, spur, grooved shafts, pins and parallel keys, bearings, tension and compression springs, beams under combined stress (bending and torsion) and bevel gearing geometry.
VariCAD contains many tools for checking the created models. It detects interferences between solids, and checks attributes of the solids so that these are correctly inserted into BOM or your corporate information system.
Surface development (sheet metal unbending). VariCAD can also create developed (unbent) surfaces of sheet metal parts or 3D solids. For further processing, the XY coordinates of developed surfaces can be saved into a text file. The user can enter bending coefficients in order to customise his calculations to reflect material and technology.
Mechanical part and symbol libraries. VariCAD contains both 3D and 2D libraries of mechanical parts (ANSI, DIN) such as bearings, nuts, cotters to name a few, hydraulic and electrical symbols, welding and tolerance symbols, etc.
3D-2D export. To produce conventional drafting documentation, 3D models can be easily converted into 2D drawings. By defining the views in 3D, 2D views of one or more selected solids can be created. In addition, exporting specified sections is possible. After changes in 3D, VariCAD supports updates of a 2D drawing.
2D drawing and editing. In VariCAD, the drawing functions are optimised for ease of use in engineering. Some handy features of 2D drawing include tolerance symbols, welding symbols, finish symbols, advanced dimensioning, ortho mode, hatching with automatic border detection, drawing layers, block creation, rectangular grid, auxiliary construction lines, automatic detection of objects and snap points and numerous snap modes. Drawings can be made in millimetres or inches.
BOM and title blocks. To maintain the data structure of the product, VariCAD provides certain tools. There are links between attributes of parts and content of title blocks. The user can create a BOM from an assembly or easily modify the database using commands like sorting of information and mass attribute changes. Each part can contain attributes, like name, supplier or type of material. Such data can be used for filling of title blocks, creation of BOM, material requisitions or other purposes.
It is possible to export the data structure of the product (BOM) into other systems or into a spreadsheet. A mask is used for BOM customisation where a user can modify it exactly according to the requirements.
VariCAD can interchange files with other CAD systems. One can export STEP (3D), STL (3D), IGES (3D), DWG (2D) and DXF (2D) files, and import STEP (3D), DWG (2D) and DXF (2D) files. The files can either be converted individually or in batch routines (converting multiple files in one step).
VariCAD is available in English, Japanese, Chinese, Portuguese and German versions. It uses DXF, DWG (AutoCAD), IGES, STL and STEP file formats for data exchange. The files exported from VariCAD can be further processed in rendering, FEA or CAM systems.
VariCAD can be run on MS Windows or Linux (both 32- and 64-bit versions). It uses Unicode, which supports other fonts (Japanese, Chinese, Cyrillic, etc) and special characters used in technical drawings.
The author is a tech correspondent at EFY Bengaluru