CAD systems: the purpose of creation, composition and structure

CAD systems are computer-aided design systems that are used to perform a variety of design procedures with the use of computer technology. Also, with the help of such software, technological and design documentation for individual buildings, products or structures is created. Modern CAD systems are used in the most diverse fields of activity of modern man, and practically for everyone there is a unique type of such utilities.

What it is?

Often, the abbreviation CAD is considered to be the standard English-speaking analogue of the term CAD, but in fact it is not quite so. CAD systems can not be considered as a full-fledged CAD analog as an organizational and technical system, since GOST brings this phrase in the form of a standardized English-language equivalent of the term "computer-aided design". Thus, in English the term CAD is translated more as CAE system, but in a number of foreign sources it is stated that the term SAE is a generalized concept, which includes the use of any computer technology in engineering work, including also CAM and CAD.

Why is this necessary?

CAD systems are used mainly to maximize the efficiency and productivity of engineers by fully automating the design and further preparation of production. Thus, due to their application, the following advantages are achieved:

• The design time is significantly shortened;
• The amount of labor required for planning and design is reduced;
• The total prime cost of manufacturing and design is significantly reduced, which directly affects the operating costs;
• An increase in the technical and economic level, as well as the quality of the results of the conducted design work;
• Reduction of costs required for testing and full-scale modeling.

As input data, modern CAD-systems use various technical experts knowledge, which are engaged in refinement of results, introduction of various design requirements, verification of the received design, its modification and many other things.

The implementation of the computer-aided design system is carried out as a set of applied utilities with the help of which design is provided, as well as further drawing and three-dimensional modeling of structures or bulk and flat parts.

In most cases, CAD-systems include modules for modeling three-dimensional structures, as well as the design of drawings and various design text documents.

They are classified mainly on several parameters:

• Variety and type of the object under consideration;
• Level of automation of the design procedure;
• Complexity of the created object;
• The complexity of the automation process;
• Number of used documents;
• The nature of the documents used;
• The total number of levels that will be present in the technical support structure.

Special purpose

Depending on what the tasks of CAD-systems are implemented, they are divided into several groups:

• Automation of three-dimensional or two-dimensional geometric design, as well as the creation of various technological or design documentation.
• Design and further creation of drawings.
• Conducting geometric modeling.
• Automation of various engineering calculations, dynamic simulation, as well as analysis and simulation of physical processes with subsequent verification and optimization of products.
• A subclass of SAE tools used for computer analysis.
• Means intended for technological preparation of the production process of various products, which allows to automate the programming procedure and further control equipment with GAPS or CNC.
• Means, intended for automation of planning processes of various technological processes, used at the joint of CAM and CAD systems.

Most CAD systems can combine the solution of various tasks that relate to different aspects of design - a complex or integrated CAD system.

Common international classification

Modern classification distributes them into several categories:

• Drawing-oriented systems, which first appeared in the seventies of the last century, but can still be used in some situations;
• Systems that create three-dimensional electronic models of objects, which makes it possible to solve various problems related to modeling up to the production procedure;
• Systems that support the concept of a complete electronic description of an object.

The latter type is a technology that provides the development and subsequent support of the information electronic model throughout its life cycle, including conceptual and operational design, full-fledged marketing, production, technological preparation, operation, and disposal and repair.

In modern technical and educational literature, as well as various state standards, the abbreviation CAD is interpreted as the "Computer-Aided Design System", but here the concept "Automation system for design works" corresponds most exactly, but it is more difficult to perceive, . Often it happens that, when designing in CAD systems, one can notice an incorrect interpretation of the "Automatic Design System", although in fact this is inherently erroneous. Do not forget that the concept of "automatic" provides completely independent operation of the system without the need for any human participation, while CAD still requires the execution of some tasks by the person himself, and full automation refers only to individual procedures and operations .

Not quite true is also the concept of "Software Automated Design", because it can be called too narrowly focused. Of course, at the moment CAD is considered only as application software necessary for carrying out project activities, but in fact in the domestic literature and various government standards, CAD is viewed as a more extensive concept, which includes not only software tools.

CAD in dentistry

The majority of modern dental clinics use CAD. CAD systems in dentistry are used to produce high-quality dentures, they have been used for more than ten years to manufacture abutments for implants, crowns and various prostheses, all of which are of excellent quality and high precision. The essence of this technology lies in the fact that initially three-dimensional modeling of the created structure on the computer is carried out, and only then, using the project model, they make the production on the milling unit.

Thus, dentists get a lot of advantages due to the use of CAD technology in their work. CAD systems in dentistry are used most often as follows:

• First the doctor conducts the removal of the impression, which is then sent to the laboratory;
• After the delivery of the casts are placed in a specialized scanner, creating a model of the future product;
• The CAD system enters into the business: the 3D model turns into a specialized file that will serve as a data source for the milling unit;
• Using the resulting file, the milling unit is manufactured from a special workpiece made of zirconium oxide;
• In the end, the resulting frame is carefully covered with ceramic mass and baked.

CAD / CAM systems in dentistry make it possible to manufacture crowns made of zirconium dioxide, which differ from metal containing products with a lot of advantages. By themselves, these products have almost no differences in color from natural teeth, as the choice of shade is carried out even in the process of making the frame. Then the frame is carefully covered with a special ceramic mass, which has a translucent and translucent structure, and also includes a wide range of colors in its palette, which makes it possible to make crowns similar to natural teeth.

By itself , zirconium oxide is highly biocompatible, even when compared with precious metals, and is a hypoallergenic material, as confirmed by a number of scientific clinical studies. However, in fact, crowns based on the frame of zirconium oxide are not the only type of products for which CAD / CAM systems are used. CNC machine based on such technologies allows to produce:

• Various bridges;
• Temporary crowns;
• Individual abutments.

In addition to the already mentioned zirconia, a variety of materials can be used in the manufacturing process, including plastics, waxes, cobalt and titanium, and chromium.

What are the advantages?

These technologies provide such advantages as:

• The maximum possible accuracy of manufacturing with minor deviations;
• Full automation of production processes, which almost completely eliminates the possibility of errors;
• The possibility of using a variety of materials;
• The possibility of carrying out modeling and manufacturing procedures in different places;
• Marginal productivity of any ongoing processes.

CAD in mechanical engineering

CAD-system (T-FLEX CAD and others) has found wide enough distribution in the field of mechanical engineering which differs on three levels - the bottom, average and top. This division appeared at the turn of the eighties and nineties of the last century.

The lower level includes CAD / CAM / CAE-systems with low cost, which are mainly oriented to 2D-graphics, that is, they are mainly aimed at automation of drawing works. As technical support for light CAD, personal computers were used, which already at that time were substantially inferior in functionality to full-fledged workstations.

Top-level systems, or, as they are still called, heavy CAD, were designed to be used on all kinds of mainframes or workstations. Such systems turned out to be much more versatile, but at the same time they had rather high cost, focusing mainly on surface and solid modeling. The preparation of various drawing documentation in them is often carried out by means of preliminary development of special geometric three-dimensional models. After this system, in which the 3D modeling function was limited solely to solid models, that is, occupying an intermediate position between the heavy and light, got their own, average level.

To date, the development of CAD has already led to the fact that in most middle-level systems, special surface modeling tools began to appear, and functions available for use in personal computers have also become acceptable for modern top-level systems. Due to this, even those principles on which the difference of medium and heavy systems were realized earlier changed. Modern CAD-systems of a heavy level are now commonly called CAE / CAD / CAM / PDM, that is, those that simultaneously include such features as:

• Technological and design engineering;
• Engineering analysis;
• Project information management;
• Extended composition of special program modules.

In contrast, modern middle-tier systems are usually called mainstream, mid-range or simply serial.

Systems of the same level can be called approximately equivalent in terms of functionality, since some new achievements appearing in a certain software and methodological complex will be implemented in the near future in new versions of others. In CAD large companies quite often it is accepted to combine simultaneously several systems of different levels. Often, this is due to the fact that almost all design procedures can be carried out on CAD systems of the middle and lower levels, and in addition, the heavy ones are too expensive. It is for this reason that enterprises purchase top-level software licenses in a fairly limited number, and the majority of modern customer bases are provided at the expense of lower and middle levels.

In this case, it often happens that CAD / CAE-systems can have certain problems in terms of information exchange among themselves, but such disruptions are solved by using special formats and languages adopted in CALS-technologies, although to ensure an undistorted transfer of geometric data through Intermediate unified languages have to overcome some difficulties.

Structure

Like any other complex system, CAD includes several subsystems that can be projecting or serving.

The first are engaged in direct implementation of a variety of design work. As an example, we can cite subsystems of three-dimensional geometric modeling of all possible mechanical objects, circuit analysis, creation of design documentation or trace connections of printed circuit boards.

Serving subsystems are intended to ensure the normal working capacity of projectors, and their combination is often among specialists called the system environment of CAD. Typical serving subsystems often use project data management databases, various subsystems for the development and subsequent maintenance of CASE software, as well as training, designed to facilitate the adoption by users of technologies implemented in CAD.

Structuring in various aspects allowed the appearance of types of CAD support, which today are given only seven:

• Technical, which includes various hardware ;
• Mathematical, combining all sorts of mathematical methods, algorithms and models;
• Software, which is a computer program CAD;
• Information, which includes databases, management systems for these databases, as well as many other information used in the design process;
• Linguistic, expressed in the form of languages of communication between computers and designers, languages of data exchange between technical CAD tools and programming languages;
• Methodological, which includes all kinds of design technologies;
• Organizational, executed in the form of job descriptions, staff schedules and other documentation, through which the regulation of the operation of project enterprises is carried out.

It is worth noting that the entire body of information that is used in the design process, experts called the information fund CAD. The database is an ordered set of information, which reflects the various characteristics of objects and their relationship in a particular subject area. Access to the database for studying, recording and subsequent correction of data is carried out through the DBMS, and the set of DBMS and DB is usually called BDD, that is, a data bank.

Classification

CAD / CAM design systems are classified according to a number of characteristics, such as application, purpose, scope (how complex are the tasks solved), as well as the nature of the underlying subsystem.

On applications among the most popular and representative it is necessary to allocate the following groups of CAD:

• Used in the field of general engineering (due to which they are usually called machine-building);
• Used in the field of radio electronics;
• Used in construction and architecture.

In addition, there is also a sufficiently large number of specialized systems or allocated in the groups listed, or representing a completely independent classification branch. As an illustrative example we can cite CAD of large integrated circuits, electric machines, aircraft and a number of others.

Separate software and methodological complexes differ in scale, including a complex for testing the strength of various mechanical products according to the finite element method or a complex of electronic circuit testing, as well as systems with a unique architecture of not only software, but also technical support.

The basic subsystem

Here are the following varieties of CAD:

• Based on the subsystem of geometric modeling and computer graphics. Such CAD systems are mainly oriented to various applications, in which design is the main design procedure, that is, a clear definition of spatial forms, as well as the mutual location of objects. That's why this group includes many CAD systems from the engineering industry, based on graphics cores. In our time, it is often common to use unified graphics cores.
• Based on the DBMS. They mainly focus on those applications in which there is an opportunity, conducting relatively simple mathematical calculations, to process a fairly large amount of information. They can often be found in technical and economic applications, such as the design of business plans, but they are often used in the design of large objects like control panels in automatic systems.

In addition, there are also complex CAD systems, which include subsystems of all previous types. As typical examples of such complex systems, it is worthwhile to bring software that is actively used in modern engineering, or CAD software. The latter includes DBMS and various subsystems for the design of components, functional and logic circuits, crystal topology, as well as tests for the analysis of the shelf life of manufactured products. In order to ensure the normal management of such complex programs, it is customary to use specialized system environments.