CAD CAM Trends | CAD CAM Integration

Stewart D. Siebell

Trends In CAD/CAM That Will Shape The Future

The rest of this decade will see continued advances in techniques for creating and manipulating workpiece geometry. Standards for user interfaces, data transfer, and computer architecture will give users new flexibility. All of these developments promise to have a significant impact on numerical control and other manufacturing applications.

Where are numerical control (NC) and computer-aided design/computer-aided manufacturing (CAD/CAM) headed? What current trends are influencing the direction these key manufacturing technologies are taking? The answers to these important questions should help us anticipate and plan for the future.

For years, manufacturing companies in the United States have been criticized for a lack of long-range planning. Intense pressures to meet short-term goals are usually blamed for this situation. But another factor has also been at work. Long-range planning means accepting a certain degree of uncertainty. Technology changes so rapidly that it is very difficult to predict what techniques, processes, or systems will predominate or become obsolete.

But decisions about technology are not like dropping an anchor. They are like spreading a sail. Leaders of a manufacturing enterprise must set a course toward a destination, then be ready to shift with the winds.

The following pages are meant to be a breezy review of the major currents blowing us toward the future. They represent the forces that will both guide and propel the decision-making process.

Capture And Share Knowledge

The collective knowledge of individuals within a company is a clear corporate asset. In the 90s, CAD/CAM systems will provide the tools to electronically capture this knowledge and apply it to the design and manufacture of components. Current CAD/CAM technology is related primarily to the dimensional characteristics of a component. However, other properties, such as material, cost, manufacturability, inspectability, assembly fit, tolerances, and so on, are equally important. Design standards, rules, and constraints also impact the design.

Today, manufacturing know-how is mainly locked in the minds of a few individuals at each company. CAD/CAM systems will be extended to capture and utilize this knowledge. This will be accomplished by direct coupling with dedicated knowledge-based engineering systems or by adding that capability to the base CAD/CAM functionality. Knowledge-based engineering will become an integral component of a CAD/CAM system.

New software tools will help these experts record the information and thought processes with which they make decisions. Once captured, these records become readily available to those making the actual design decisions on future projects. These tools will have a major impact on automation of the design and manufacturing process.

Simultaneous Engineering

Sharing information is another urgent issue where new techniques and methodologies will have an impact. One of the most important of these is simultaneous engineering. Simultaneous engineering (or concurrent engineering) can be defined as a methodology in which the design of the product is accomplished simultaneously with the design of the process to produce the product. In this methodology, design engineering works together with manufacturing engineering and other related functions during the design phase to incorporate downstream manufacturing considerations into the product design (Figure 1).

Companies that have implemented simultaneous engineering have typically experienced fewer design changes, shorter lead times, lower manufacturing costs and improved quality.

This concept not only applies within a company, but can be extended to the supplier network. As a company better understands the issues being faced by the supplier, and the supplier offers design suggestions based upon manufacturing knowledge, a more effective process results. The inclusion of suppliers and customers into the manufacturing process creates a "virtual factory." Different companies will work so closely together as a team that it will be as if they were actually a dedicated organization under one roof.

Acceptance of Industry Standards

Proprietary computing systems were commonplace from the 1970s to the mid-1980s. Mainframe- and mini-based systems employed proprietary architectures, operating systems, data managers and data communication networks. Early workstation systems also employed proprietary architectures. Proprietary systems contributed to the "islands of automation" that developed in the 1980s.

In the 1990s, open architectures employing industry standard components will be demanded by users and provided by vendors. Here are some important formal and de facto standards that reflect this trend:

* UNIX has become accepted as the de facto standard operating system for engineering workstations. Although variants of UNIX remain, efforts are underway to move to a common system. * C has become the standard programming language for development of CAD/CAM application systems. Its object-oriented variant, C++, is likely to evolve in the 1990s as a de facto standard as object orientation becomes commonplace. The main concept behind object orientation is that repetitive programming code should be written only once and shared by a number of other programs.

Object orientation provides a natural grouping of all characteristics associated with an object. An object contains both data and procedures or actions. A part can be defined as an object as opposed to a set of related lines, arcs, circles, surfaces, or solids. This simplifies the programming task for the developer and will provide an efficient system for the user. * Initial Graphics Exchange Specification (IGES) has become an ANSI standard data format to facilitate digital exchange of database information among computer-aided design systems. IGES will remain a widely used and supported standard. * Product Data Exchange Specification (PDES) supports the exchange of full product models. In addition to geometric information, PDES supports non-geometric information like manufacturing features, tolerance specifications, material properties and surface finish specifications. Upon implementation, it is likely to evolve as an industry standard. * Standards for Exchange of Product Model Data (STEP) is an international activity to move the PDES draft forward into a formal standard established by ISO, the world standards-making body. * Programmer's Hierarchical Interactive Graphics System (PHIGS) is a functional specification of the interface between an application program and its graphics support system. Graphics Kernal System (GKS) is a related specification that provides uniform graphics input and output independent of the hardware. * Network File System (NFS) has become the de facto standard for remote access to files within a local area communication network. * Ethernet-TCP/IP is a network based on evolving ISO standards utilizing TCP/IP formats. It has become the de facto standard for a local area network. * X Window is a specification that allows information from several databases to be accessed and displayed on one screen at the same time. Since both Open Look and the Open Systems Foundation/Motif graphical user interfaces comply with X Windows, it has become a de facto standard for the development of UNIX user interfaces. * NURBS (Non-Uniform Rational B Spline) has evolved as the standard mathematical technique used to define complex curves and surfaces.

Transparent Computing

With the acceptance of industry standards, transparent computing within heterogeneous computing environments becomes possible. In other words, computers work together to solve problems as if they were all part of a single integrated system. The user does not "see" nor is concerned with which processor does the work (hence the term "transparent"). Thus, users have ready access to all relevant computing resources within an environment (Figure 2).

Personal computers and workstations will be organized into work groups. This concept recognizes the economic value in sharing a file server, printer, and plotter among users within a given work group.

At a higher level, computing architectures will be implemented that include the networking of a range of processors from personal computers to supercomputers and supporting equipment such as file servers, printers, plotters, scanners, and so on.

Users will be able to "mix and match" to obtain the most effective application system to accomplish the task. For example, the most appropriate NC programming system can be installed with the most appropriate drafting system.

Enhanced Geometry Creation

The 1990s will see substantial enhancements in geometry creation, including solid modeling, feature-based geometry, associativity, inference systems, parametric design, and variational geometry functionality. Moreover, system architectures of the 1990s are likely to have a separate geometry subsystem that will serve all applications.

Geometry subsystems are now being independently developed and marketed in the same manner as database management, graphics, and data communication systems. They will provide a geometry toolkit to be utilized by all applications.

Advanced geometry software systems will provide an architecture in which wireframe, surface, and solid representations can be intermixed within the same model. Such a system will support applications that involve time, the fourth dimension. For example, this capability will permit direct computation of potential collisions between two solid objects moving through space, as in robotic or machining applications.

Solid models provide a complete and unambiguous representation of a real object. They permit a more direct and accurate computation of mass properties. Internal characteristics of the object can also be included in the model. Solid product models will form the core for a single product definition in a CAD environment. All functions will reference this model. NC machining systems, now under development in some firms, will be introduced to machine directly off a solid model.

Feature-based or form-feature-based modeling is a higher level of design. It recognizes that designers and engineers generally think in terms of blind holes, through-holes, slots, shafts, chamfers, ribs, rounds, fillets, and so on, rather than lines, circles, arcs, or Boolean manipulation of solid objects such as boxes, cylinders, or cones. Furthermore, the direct creation of a feature, as opposed to a buildup of the feature, improves the productivity of designers.

A related capability is associativity. In associative systems, relationships are established between models and dimensions in such a way that changes in the model or its dimensions result in an automatic update of other related models or dimensions. Further, a change to a part within an assembly can trigger a corresponding change to that part in other assemblies.

In an inference system, the CAD system infers the next step by the operator. It automatically generates the next line, arc, circle, and so on. This is usually done by placement of the mouse pointer or other input device. By so doing, design productivity is increased. If the system inference is incorrect, it can be undone and re-entered.

Parametric design systems were introduced in the 1980s. In these systems, parameters are established as opposed to actual dimensions. Relationships can also be established among the parameters. For example, one side of an object is always twice that of another side of an object. When combined with an associativity capability, a powerful system results. A change in one dimension can also change other dimensions and update the geometric model.

A similar but somewhat more powerful capability is that of variational geometry. A variational design system completely defines the problem with a series of simultaneous equations. Thus, it offers greater flexibility by removing restrictions on interdependencies and solves all the values at once. If engineers change any type of condition or vary any design parameter, the variational design system can still adjust all other design parameters to arrive at a new solution that accounts for interactions among all the conditions defined.

A word about rapid prototyping is appropriate here. Prior to full-scale production, most manufacturers produce multiple prototypes in order to see and touch a part directly, to hold and examine the thing without recourse to abstract geometry. This step can involve significant time and cost.

Technology has been and is continuing to be introduced that reduces this time and cost substantially. The original technology is termed stereolithography but other approaches such as fused deposition modeling (Figure 3) have also appeared. In all cases, systems utilize the geometry from a CAD model as the starting point. Typically, the model is then mathematically sliced to obtain the geometry at a given elevation. Material is then deposited, layer by layer, to build the physical model.

Changes In User Interfaces

Significant changes will take place in user interfaces to a graphics-based computing system. These changes will make the computer more like an extension of the user's mind. The impact of a new user interface was made strikingly clear with the introduction of the Macintosh family of personal computers by Apple Computer Corp. A totally new look and feel for the user was created by the mouse input, windows, pop-up menus, icons, and so on that were introduced with the Mac.

Proprietary graphical user interfaces (GUI) are giving way to pseudo standard solutions for UNIX-based systems. At the lowest level, the X windowing system serves as the clear standard. At the next higher level, where the look and feel is created, the Open Software Foundation's Motif and the UNIX International's Open Look are the two primary competitors for a de facto GUI standard. Stand-alone GUIs based upon these standards are likely to become available and serve as common front-ends to CAD/CAM systems that incorporate a variety of different applications.

Other innovations on the near horizon include multimedia, voice input and virtual reality. In multimedia systems, documents or files will be created with audio, animation, and/or video, as well as the conventional data, text, and graphics. This combination is then simultaneously presented on the display. Multimedia input will allow the user to absorb greater quantities of information by using more than one sense to process information. A message could include voice comments, animation, text, and full-motion color video--even music.

Voice input is likely to become practical in this decade. The user can then enter commands to a CAD/CAM system by voice as opposed to keyboard, mouse, tablet, and other input forms.

In a virtual reality system, the user is placed within the environment of the computer visualization. An architect can walk around inside a virtual building that is being designed. An NC programmer can "walk" along a tool path. A doctor can explore a patient's heart before surgery. In virtual reality, one can directly manipulate the simulation by grasping, moving, and changing elements of the simulation with a gloved hand. This may be the ultimate intuitive user interface.

Product Data Management

Many organizations using CAD/CAM now have thousands of files representing drawings, engineering analysis results, and other information related to product definition. Managing these collections has become a problem. Product Data Management (PDM) software is emerging as a solution.

A PDM system collects, organizes, files, accesses, and controls any type of data about a company's products. Typical information managed by a PDM system includes specifications, drawings, geometric models, models produced by finite element analysis, process plans, NC programs, and so on. Although product definition data could be in hard copy form, it is generally in digital files.

PDM software is provided by CAD/CAM vendors and independent suppliers. Good capability is now available in homogeneous environments and, in the 1990s, management of files in distributed, heterogeneous environments will be commonplace. PDM systems will soon become more closely integrated with both CAD/CAM and standard management information systems.

A related technology is image management systems. In image management systems, paper documents, such as drawings, are scanned into electronic form. The documents can then be indexed, manipulated, accessed within a network, and managed as in a PDM system.

Maturity

The CAD/CAM industry has become a multibillion dollar industry. In the 1990s, it will become relatively mature. Industry growth rates, although substantial by most standards, will ease. Acquisitions, mergers, and alliances will accelerate. The trends noted, for the most part, are evolutionary and not revolutionary. Yet CAD/CAM in general, and automated manufacturing in particular, will remain an exciting field.

New technologies will continue to emerge, and for the most part, will be introduced by niche companies. User organizations will become more sophisticated and hence, more inclined to implement the best product for the task at hand.

World class manufacturing demands the appropriate utilization of advanced technology. It is essential for those firms striving to remain competitive in a worldwide marketplace.

PHOTO : Fig. 1--Simultaneous engineering will be greatly facilitated by access to shared databases that capture the expertise of those who make decisions about marketing and manufacturing.

PHOTO : Fig. 2--Access to all relevant computing resources will be a cornerstone of systems architecture in the 1990s. Acceptance of industry standards makes this possible.

PHOTO : Fig. 3--CAD/CAM systems will give users powerful new tools for creating geometry, not only in the abstract on a computer screen but also in physical reality. The computer image on the left was transformed into its 3D counterpart by a rapid prototyping technique called fused deposition modeling, which was developed by Stratasys, Inc.

PHOTO : The graphical user interface defines how a user responds to and interacts with a CAD/CAM system. For example, pop-up menus (the various boxes that seem superimposed on this view of a mold cavity being designed with CAMAX software) list choices available to the user without disturbing the design image on the screen. In this case, the user defines machining parameters by simply making the appropriate selection from each menu.

Stewart D. Siebell, Chief Executive Officer CAMAX Systems, Inc. Minneapolis, Minnesota