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COMPUTER AIDED MANUFACTURING PDF

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aided manufacturing, simply called CAM. CAM is closely related to the computer- aided design. (CAD) because the output information about the products from. CAM architectures; computer aided manufacturing; computer systems; . Integrated Computer Aided Manufacturing, Manufacturing Technology Division. PDF | On Jan 1, , Sotiris Makris and others published Computer Aided Manufacturing (CAM).


Computer Aided Manufacturing Pdf

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8. Computer-Aided Manufacturing. ▫ Introduction. ▫ Part Production Cycle. ▫ Manufacturing Systems. ▫ Manufacturing Processes. ▫ Casting/Molding. One part of the article contains the problem of the Computer-Aided Manufacturing . The specific examples of CAD/CAM system Pro/ENGINEER applications in. DEFINITION: Effective utilization of computer technology in the. MANAGEMENT, CONTROL and OPERATIONS of the manufacturing facility through either direct.

Semi-finishing This process begins with a roughed part that unevenly approximates the model and cuts to within a fixed offset distance from the model. The semi-finishing pass must leave a small amount of material called the scallop so the tool can cut accurately, but not so little that the tool and material deflect away from the cutting surfaces. Finishing Finishing involves many light passes across the material in fine steps to produce the finished part.

When finishing a part, the steps between passes is minimal to prevent tool deflection and material spring back. In order to reduce the lateral tool load, tool engagement is reduced, while feed rates and spindle speeds are generally increased in order to maintain a target surface speed SFM. In addition to modifying speeds and feeds, machinists will often have finishing specific endmills, which never used as roughing endmills. This is done to protect the endmill from developing chips and flaws in the cutting surface, which would leave streaks and blemishes on the final part.

Contour milling In milling applications on hardware with four or more axes, a separate finishing process called contouring can be performed. Instead of stepping down in fine-grained increments to approximate a surface, the work piece is rotated to make the cutting surfaces of the tool tangent to the ideal part features.

Continuous-flow processes Continuous dedicated production of large amounts of bulk product. Examples include continuous chemical plants and oil refineries 2. Mass production of discrete Dedicated production of large quantities of products one product with perhaps limited model variations.

Examples include automobiles, appliances, and engine blocks. Batch production Production of medium lot sizes of the same product or component.

The lots may be produced once or repeated periodically. Examples include books, clothing, and certain industrial machinery. Job shop production Production of low quantities, often one of a kind, of specialized products. The products are often customized and technologically complex.

Examples include prototypes, aircraft, machine tools, and other equipment. Continuous-flow Flow process from beginning to end processes Sensor technology available to measure important process variables Use of sophisticated control and optimization strategies Fully computer-automated plants 2. Mass production Automated transfer machines of discrete products Dial indexing machines Partially and fully automated assembly lines Industrial robots for spot welding, parts handling, machine loading, spray painting, etc.

Computer-integrated manufacturing systems 4. It has also demonstrated itself, especially in recent years, to be a very powerful tool in design and manufacturing. In this and the following two chapters, we consider the application of computer technology to the design of a product.

This secton provides an overview of computer-aided design. The CAD system defined As defined in previous section, computer-aided design involves any type of design activity which makes use of the computer to develop, analyze, or modify an engineering design.

Interactive computer graphics denotes a user-oriented system in which the computer is employed to create, transform, and display data in the form of pictures or symbols. The user in the computer graphics design system is the designer, who communicates data and commands to the computer through any of several input devices.

The computer communicates with the user via a cathode ray tube CRT. The designer creates an image on the CRT screen by entering commands to call the desired software sub-routines stored in the computer. In most systems, the image is constructed out of basic geometric elements- points, lines, circles, and so on. Through these various manipulations, the required details of the image are formulated.

The typical ICG system is a combination of hardware and software. The hardware includes a central processing unit, one or more workstations including the graphics display terminals , and peripheral devices such as printers. Plotters, and drafting equipment. Some of this hardware is shown in Figure. The software consists of the computer programs needed to implement graphics processing on the system.

The software would also typically include additional specialized application programs to accomplish the particular engineering functions required by the user company.

It is important to note the fact that the ICG system is one component of a computer-aided design system. As illustrated in Figure, the other major component is the human designer. Interactive computer graphics is a tool used by the designer to solve a design problem.

In effect, the ICG system magnifies the powers of the designer. This bas been referred to as the synergistic effect. The designer performs the portion of the design process that is most suitable to human intellectual skills conceptualization, independent thinking ; the computer performs the task: There are several fundamental reasons for implementing a computer-aided design system.

To increase the productivity of the designer. This is accomplished by helping the designer to the product and its component subassemblies and parts; and by reducing the time required in synthesizing, analyzing, and documenting the design. This productivity improvement translates not only into lower design cost but also into shorter project completion times. To improve the quality of design. A CAD system permits a more thorough engineering analysis and a larger number of design alternatives can be investigated.

Design errors are also reduced through the greater accuracy provided by the system. These factors lead to a better design. To improve communications. To create a database for manufacturing. In the process of creating the documentation for the product design geometries and dimensions of the product and its components, material specifications for components, bill of materials, etc.

The process of designing something is characterized by Shigley as an iterative procedure, which consists of six identifiable steps or phases: Recognition of need 2. Definition of problem 3. Synthesis 4. Analysis and optimization 5.

Evaluation 6. Presentation Recognition of need involves the realization by someone that a problem exists for which some corrective action should be taken. This might be the identification of some defect in a current machine design by an engineer or the perception of a new product marketing opportunity by a salesperson.

Definition of the problem involves a thorough specification of the item to be designed. This specification includes physical and functional characteristics, cost, quality, and operating performance. Synthesis and analysis are closely related and highly interactive in the design process. A certain component or subsystem of the overall system is conceptualized by the designer, subjected to analysis, improved through this analysis procedure, and redesigned.

The process is repeated until the design has been optimized within the constraints imposed on the designer. Evaluation is concerned with measuring the design against the specifications established in the problem definition phase. This evaluation often requires the fabrication and testing of a prototype model to assess operating performance, quality, reliability, and other criteria.

The final phase in the design process is the presentation of the design. This includes documentation of the design by means of drawings, material specifications, assembly lists, and so on. Essentially, the documentation requires that a design database be created. Figure illustrates the basic steps in the design process, indicating its iterative nature.

The general design process as defined by Shigley. Mechanical design includes the drawing of the complete product as well as its components and subassemblies, and the tools and fixtures required to manufacture the product. Electrical design is concerned with the preparation of circuit diagrams, specification of electronic components, and so on. Similar manual documentation is required in other engineering design fields structural design, aircraft design, chemical engineering design, etc.

In each engineering discipline, the approach has traditionally been to synthesize a preliminary design manually and then to subject that design to some form of analysis. The analysis may involve sophisticated engineering calculations or it may involve a very subjective judgment of the aesthete appeal possessed by the design.

The analysis procedure identifies certain improvements that can he made in the design. As stated previously, the process is iterative.

Each iteration yields an improvement in the design. The trouble with this iterative process is that it is time consuming. Many engineering labor hours are required to complete the design project.

Geometric modeling 2. Engineering analysis 3. Design review and evaluation 4. Automated drafting These four areas correspond to the final four phases in Shigley's general design process, illustrated in Figure. Geometric modeling corresponds to the synthesis phase in which the physical design project takes form on the ICG system. Engineering analysis corresponds to phase 4, dealing with analysis and optimization. Design review and evaluation is the fifth step in the general design procedure.

Automated drafting involves a procedure for converting the design image data residing in computer memory into a hard-copy document. The following four sections explore each of these four CAD functions. Geometric modeling In computer-aided design, geometric modeling is concerned with the computer-compatible mathematical description of the geometry of an object. The mathematical description allows the image of the object to be displayed and manipulated on a graphics terminal through signals from the CPU of the CAD system.

The software that provides geometric modeling capabilities must be designed for efficient use both by the computer and the human designer. The first type of command generates basic geometric elements such as points, lines, and circles. The second command type is used to accomplish scaling, rotating, or other transformations of these elements. The third type of command causes the various elements to be joined into the desired shape of the object being creaed on the ICG system. During the geometric modeling process, the computer converts the commands into a mathematical model, stores it in the computer data files, and displays it as an image on the CRT screen.

The model can subsequently be called from the data files for review, analysis, or alteration.

There are several different methods of representing the object in geometric modeling. The basic form uses wire frames to represent the object. In this form, the object is displayed by interconnecting lines as shown in Figure.

Wire frame geometric modeling is classified into three types depending on the capabilities of the ICG system. The three types are: Two-dimensional representation is used for a flat object. This goes somewhat beyond the 2D capability by permitting a three-dimensional object to be represented as long as it has no side-wall details. This allows for full three-dimensional modeling of a more complex geometry. Even three-dimensional wire-frame representations of an object are sometimes inadequate for complicated shapes.

Wire-frame models can be enhanced by several different methods. Figure shows the same object shown in the previous figure but with two possible improvements. Some CAD systems have an automatic "hidden- line removal feature," while other systems require the user to identify the lines that are to be removed from view. Another enhancement of the wire-frame model involves providing a surface representation which makes the object appear solid to the viewer.

However, the object is still stored in the computer as a wire-frame model. Courtesy of Computervision Corp. Solid model of yoke part as displayed on a computer graphics system. The most advanced method of geometric modeling is solid modeling in three dimensions.

This method, illustrated in Figure, typically uses solid geometry shapes called primitives to construct the object.

Computer-Aided Manufacturing

By means of colour, it is possible to display more information on the graphics screen. Colored images help to clarify components in an assembly, or highlight dimensions, or a host of other purposes. Engineering analysis In the formulation of nearly any engineering design project, some type of analysis is required. The analysis may involve stress-strain calculations, heat-transfer computations, or the use of differential equations to describe the dynamic behavior of the system being designed.

The computer can be used to aid in this analysis work. It is often necessary that specific programs be developed internally by the engineering analysis group to solve a particular design problem. In other situations, commercially available general-purpose programs can be used to perform the engineering analysis.

We discuss two important examples of this type: Analysis of mass properties Finite-element analysis The analysis of mass properties is the analysis feature of a CAD system that has probably the widest application.

It provides properties of a solid object being analyzed, such as the surface area, weight, volume, center of gravity, and moment of inertia. For a plane surface or a cross section of a solid object the corresponding computations include the perimeter, area, and inertia properties. Probably the most powerful analysis feature of a CAD system is the finite- element method.

With this technique, the object is divided into a large number of finite elements usually rectangular or triangular shapes which form an interconnecting network of concentrated nodes. By using a computer with significant computational capabilities, the entire Object can be analyzed for stress-strain, heat transfer, and other characteristics by calculating the behavior of each node.

Some CAD systems have the capability to define automatically the nodes and the network structure for the given object. The output of the finite-element analysis is often best presented by the system in graphical format on the CRT screen for easy visualization by the user, For example, in stress-strain analysis of an object, the output may be shown in the form of a deflected shape superimposed over the unstressed object.

This is illustrated in Figure. Color graphics can also be used to accentuate the comparison before and after deflection of the object. This is illustrated in Figure for the same image as that shown in Figure.

If the finite-element analysis indicates behavior of the design which is undesirable, the designer can modify the shape and recompute the finite- element analysis for the revised design. Finite-element modeling for stress-strain analysis. Graphics display shows strained part superimposed on unstrained part for comparison. Design review and evaluation Checking the accuracy of the design can be accomplished conveniently on the graphics terminal.

Semiautomatic dimensioning and tolerancing routines which assign size specifications to surfaces indicated by the user help to reduce the possibility of dimensioning errors. A procedure called layering is often helpful in design review. For example, a good application of layering involves overlaying the geometric image of the final shape of the machined part on top of the image of the rough casting. This ensures that sufficient material is available on the casting to acccomplish the final machined dimensions.

This procedure can be performed in stages to check each successive step in the processing of the part. Another related procedure for design review is interference checking. This involves the analysis of an assembled structure in which there is a risk that the components of the assembly may occupy the same space. This risk occurs in the design of large chemical plants, air-separation cold boxes, and other complicated piping structures. One of the most interesting evaluation features available on some computer- aided design systems is kinematics.

The available kinematics packages provide the capability to animate the motion of simple designed mechanisms such as hinged components and linkages.

Without graphical kinematics on a CAD system, designers must often resort to the use of pin-and-cardboard models to represent the mechanism. Automated drafting Automated drafting involves the creation of hard-copy engineering drawings directly from the CAD data base. In some early computer-aided design departments, automation of the drafting process represented the principal justification for investing in the CAD system.

Indeed, CAD systems can increase productivity in the drafting function by roughly five times over manual drafting. These features include automatic dimensioning, generation of crosshatched areas, scaling of the drawing, and the capability to develop sectional views and enlarged views of particular path details.

The ability to rotate the part or to perform other transformations of the image e. Most CAD systems are capable of generating as many as six views of the part. Engineering drawings can be made to adhere to company drafting standards by programming the standards into the CAD system. Figure shows an engineering drawing with four views displayed. This drawing was produced automatically by a CAD system.

Note how much the isometric view promotes a higher level of understanding of the object for the user than the three orthographic views. Parts classification and coding In addition to the four CAD functions described above, another feature of the CAD data base is that it can be used to develop a parts classification and coding system. Parts classification and coding involves the grouping of similar part designs into classes, and relating the similarities by mean of a coding scheme.

Designers can use the classification and coding system to retrieve existing part designs rather than always redesigning new parts. In the conventional manufacturing cycle practiced for so many years in industry, engineering drawings were prepared by design draftsmen and then used by manufacturing engineers to develop the process plan i.

The activities involved in designing the product were separated from the activities associated with process planning. Essentially, a two-step procedure was employed. This was both time consuming and involved duplication of effort by design and manufacturing personnel.

Computer-based systems have been developed which create much of the data and documentation required to plan and manage the manufacturing operations for the product. It includes all the data on the product generated during design geometry data, bill of materials and parts lists, material specifications, etc.

Figure 4. Some of the benefits are intangible, reflected in improved work quality, more pertinent and usable information, and improved control, all of which are difficult to quantify. Other benefits are tangible, but the savings from them show up far downstream in the production process, so that it is difficult to assign a dollar figure to them in the design phase. In the subsections that follow, we elaborate on some of these advantages.

Productivity improvement in design Increased productivity translates into a more competitive position for the firm because it will reduce staff requirements on a given project. This leads to lower costs in addition to improving response time on projects with tight schedules. There are individual cases in which productivity has been increased by a factor of , but it would be inaccurate to represent that figure as typical.

Improved engineering productivity 2. Shorter lead times 3.

Reduced engineering personnel requirements 4. Customer modifications are easier to make 5. Faster response to requests for quotations 6.

Avoidance of subcontracting to meet schedules 7. Minimized transcription errors 8. Improved accuracy of design 9. In analysis, easier recognition of component interactions Provides better functional analysis to reduce prototype testing Assistance in preparation of documentation Designs have more standardization Better designs provided Improved productivity in tool design Better knowledge of costs provided Reduced training time for routine drafting tasks and NC part programming Fewer errors in NC part programming Provides the potential for using more existing parts and tooling Helps ensure designs are appropriate to existing manufacturing techniques Provides operational results on the status of work in progress Makes the management of design personnel on projects more effective Assistance in inspection of complicated parts Better communication interfaces and greater understanding among engineers, designers, drafters, management, and different project groups.

Productivity improvement in computer-aided design as compared to the traditional design process is dependent on such factors as: Complexity of the engineering drawing Level of detail required in the drawing Degree of repetitiveness in the designed parts Degree of symmetry in the parts Extensiveness of library of commonly used entities As each of these factors is increased.

It also speeds up the task of preparing reports and lists e. Accordingly, it is possible with a CAD system to produce a finished set of component drawings and the associated reports in a relatively short time. Shorter lead times in design translate into shorter elapsed time between receipt of a customer order and delivery of the final product.

The enhanced productivity of designers working with CAD systems will tend to reduce the prominence of design, engineering analysis, and drafting as critical time elements in the overall manufacturing lead time. Design analysis The design analysis routines available in a CAD system help to consolidate the design process into a more logical work pattern.

Rather than having a back- and- forth exchange between design and analysis groups, the same person can perform the analysis while remaining at a CAD workstation.

Because of this analysis capability, designs can be created which are closer to optimum. There is a time saving to be derived from the computerized analysis routines, both in designer time and in elapsed time. This saving results from the rapid response of the design analysis and from the tune no longer lost while the design finds its way from the designer's drawing board to the design analyst's queue and back again.

Computer-aided manufacturing

Fewer design errors Interactive CAD systems provide an intrinsic capability for avoiding design, drafting, and documentation errors. Data entry, transposition, and extension errors that occur quite naturally during manual data compilation for preparation of a bill of materials are virtually eliminated.

One key reason for such accuracy is simply that No manual handling of information is required once the initial drawing has been developed. Errors are further avoided because interactive CAD systems perform time-consuming repetitive duties such as multiple symbol placement, and sorts by area and by like item, at high speeds with consistent and accurate results.

Still more errors can be avoided because a CAD system, with its interactive capabilities, can be programmed to question input that may be erroneous.

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For example, the system might question a tolerance of 0. It is likely that the user specified too many zeros. The success of this checking would depend on the ability of the CAD system designers to determine what input is likely to be incorrect and hence, what to question. Greater accuracy in design calculations There is also a high level of dimensional control, far beyond the levels of accuracy attainable manually. Mathematical accuracy is often to 14 significant decimal places.

The accuracy delivered by interactive CAD systems in three- dimensional curved space designs is so far behind that provided by manual calculation methods that there is no real comparison. Computer-based accuracy pays off in many ways. Parts are labeled by the same recognizable nomenclature and number throughout all drawings. The accuracy also shows up in the form of more accurate material and cost estimates and tighter procurement scheduling.

These items are especially important in such cases as long-lead-time material purchases. Standardization of design, drafting, and documentation procedures The single data base and operating system is common to all workstations in the CAD system: Drawings are more understandable Interactive CAD is equally adept at creating and maintaining isometrics and oblique drawings as well as the simpler orthographies.

All drawings can he generated and updated with equal ease. Thus an up-to-date version of any drawing type can always he made available. Orthographic views are less comprehensible than isometrics. An isometric view is usually less understandable than a perspective view. Most actual construction drawings are "line drawings. Different colors further enhance understanding. Finally, animation of the images on the CRT screen allows for even greater visualization capability.

The various relationships are illustrated in Figure.. Improved procedures for engineering changes Control and implementation of engineering changes is significantly improved with computer-aided design. Original drawings and reports are stored in the data base of the CAD system. This makes them more accessible than documents kept in a drawing vault.

They can be quickly checked against new information. Benefits in manufacturing The benefits of computer-aided design carry over into manufacturing. These manufacturing benefits are found in the following areas: We will discuss the many facets of computer-aided manufacturing in later chapters.

In the remainder of this chapter, let us explore several applications that utilize computer graphics technology to solve various problems in engineering and related fields. Hence it is possible to select a CAD system that meets the particular computational and graphics requirements of the user firm.

Computer-aided design and manufacturing

Engineering firms that are not involved in production would choose a system exclusively for drafting and design-related functions. Of course, the CAD hardware is of little value without the supporting software for the system, and we shall discuss the software for computer-aided design in the following chapter. However, the scope of computer-aided design includes other computer systems as well.

For example, computerized design has also been accomplished in a batch mode, rather than interactively. Batch design means that data are supplied to the system a deck of computer cards is traditionally used for this purpose and then the system proceeds to develop the details of the design.

The disadvantage of the batch operation is that there is a time lag between when the data are submitted and when the answer is received back as output.

With interactive graphics, the system provides an immediate response to inputs by the user. The user and the system are in direct communication with each other, the user entering commands and responding to questions generated by the system. Computer-aided design also includes nongraphic applications of the computer in design work. These consist of engineering results which are best displayed in other than graphical form. Nongraphic hardware e. The hardware we discuss in this chapter is restricted to CAD systems that utilize interactive computer graphics.

Typically, a stand-alone CAD system would include the following hardware components: One or more design workstations. These would consist of: A graphics terminal Operator input devices One or more plotters and other output devices Central processing unit CPU Secondary storage These hardware components would be arranged in a configuration as illustrated in Figure. The following sections discuss these various hardware components and the alternatives and options that can be obtained in each category.

There would likely be more than one design workstation. It represents a significant factor in determining how convenient and efficient it is for a designer to use the CAD system. The workstation must accomplish five functions: It must interface with the central processing unit. It must generate a steady graphic image for the user.

It must provide digital descriptions of the graphic image. It must translate computer commands into operating functions. It must facilitate communication between the user and the system] The use of interactive graphics has been found to be the best approach to accomplish these functions. A typical interactive graphics workstation would consist of the following hardware Components: A graphics terminal Operator input devices A graphics design workstation showing these components is illustrated in Figure.

The technology continues to evolve as CAD system manufactures attempt to improve their products and reduce their costs. In this section we present a discussion of the current technology in interactive computer graphics terminals. Image generation in computer graphics Nearly all computer graphics terminals available today use the cathode ray tube CRT as the display device.

Television sets use a form of the same device as the picture tube. A heated cathode emits a high-speed electron beam onto a phosphor-coated glass screen. By focusing the electron beam, changing its intensity, and controlling its point of contact against the phosphor coating through the use of a deflector system, the beam can be made to generate a picture on the CRT screen.

There are two basic techniques used in current computer graphics terminals for generating the image on the CRT screen. They are: Stroke writing 2. Raster scan Other names for the stroke-writing technique include line drawing, random position, vector writing, stroke writing, and directed beam.

Other names for the raster scan technique include digital TV and scan graphics. The stroke-writing system uses an electron beam which operates like a pencil to create a line image on the CRT screen.

The image is constructed out of a sequence of straight-line segments. Each line segment is drawn on the screen by directing the beam to move from one point on the screen to the next, where each point is defined by its x and y coordinates. The process is portrayed in Figure.

Although the procedure results in images composed of only straight lines, smooth curves can be approximated by making the connecting line segments short enough. In the raster scan approach, the viewing screen is divided into a large number of discrete phosphor picture elements, called pixels. The matrix of pixels constitutes the raster. Each pixel on the screen can be made to glow with a different brightness. Color screens provide for the pixels to have different colors as well as brightness.

During operation, an electron beam creates the image by sweeping along a horizontal line on the screen from left to right and energizing the pixels in that line during the sweep. When the sweep of one line is completed, the electron beam moves to the next line below and proceeds in a fixed pattern as indicated in Figure.

After sweeping the entire screen the process is repeated at a rate of 30 to 60 entire scans of the screen per second: Graphics terminals for computer-aided design The two approaches described above are used in the overwhelming majority of current-day CAD graphics terminals. There are also a variety of other technical factors which result in different types of graphics terminals. These factors include the type of phosphor coating on the screen, whether color is required, the pixel density, and the amount of computer memory available to generate the picture.

We will discuss three types of graphics terminals, which seem to be the most important today in commercially available CAD systems. Directed-beam refresh 2. Direct-view storage tube DVST 3. Raster scan digital TV The following paragraphs describe the three basic types. We then discuss some of the possible enhancements, such as color and animation. The directed-beam refresh terminal utilizes the stroke-writing approach to generate the image on the CRT screen.

In order for the image to be continued, these picture tubes must be refreshed by causing the directed beam to retrace the image repeatedly. On densely filled screens very detailed line images or many characters of text , it is difficult to avoid flickering of the image with this process. On the other hand, there are several advantages associated with the directed- beam refresh systems. Because the image is being continually refreshed, selective erasure and alteration of the image is readily accomplished.

It is also possible to provide animation of the image with a refresh tube. The directed-beam refresh system is the oldest of the modem graphics display technologies. Other names sometimes used to identify this system include vector refresh and stroke-writing refresh. Early refresh tubes were very expensive. The term storage tube refers to the ability of the screen to retain the image which has been projected against it, thus avoiding the need to rewrite the image which has been projected against it, thus avoiding the need to rewrite the image constantly.

What makes this possible is the use of an electron flood gun directed at the phosphor coated screen which keeps the phosphor elements illuminated once they have been energized by the stroke-writing electron beam. The resulting image on the CRT screen is flicker- free.

Lines may be readily added to the image without concern over their effect on image density or refresh rates. However, the penalty associated with the storage tube is that individual lines cannot be selectively removed from the image.

Storage tubes have historically been the lowest-cost terminals and are capable of displaying large amounts of data, either graphical or textual. Because of these features, there are probably more storage tube terminals in service in industry at the time of this writing than any other graphics display terminal. The principal disadvantage of a storage CRT is that selective erasure is not possible.

Other disadvantages include its lack of color capability, the inability to use a light pen as a data entry, and its lack of animation capability.

Raster scan terminals operate by causing an electron beam to trace a zigzag pattern across the viewing screen, as described earlier. The operation is similar to that of a commercial television set. The difference is that a TV set uses analog signals originally generated by a video camera to construct the image on the CRT screen, while the raster scan ICG terminal uses digital signals generated by a computer.

For this reason, the raster scan terminals used in computer graphics are sometimes called digital TVs. Manual engraving techniques can take months to complete by hand, but one of these machines can complete the same work in hours or days. Plasma cutters are especially useful for cutting through electrically conductive materials like metals. These machines chip away at a variety of materials like metal, wood, composites, etc. Milling machines have enormous versatility with a variety of tools that can accomplish specific material and shape requirements.

The overall goal of a milling machine is to remove mass from a raw block of material as efficiently as possible. These machines also chip away at raw materials like a milling machine, they just do it differently.

A milling machine has a spinning tool and stationary material, where a lathe spins the material and cuts with a stationary tool. These machines cut a desired shape out of raw material through an electrical discharge.

This allows an EDM to melt through nearly anything in a controlled and ultra precise process. The human element has always been a touchy subject since CAM arrived on scene in the s. Parsons, skillfully operating machines required an enormous amount of training and practice. In the days of manual machining, being a Machinist was a badge of honor that took years of training to perfect. A Machinist had to do it all — read blueprints, know which tools to use, define feeds and speeds for specific materials, and carefully cut a part by hand.

Being a Machinist was, and still is, both an art and a science. These days, the Modern Machinist is alive and well as man, machine, and software combine to move our industry forward.

Skills that used to take 40 years to master can now be conquered in a fraction of the time. What does all this mean for the human element of manufacturing? The role of a Traditional Machinist is shifting. In a typical workflow the Programmer will hand off his program to the Setup Operator, who will then load the G-code into the machine. Once the machine is ready to roll, the Operator will then make the part. In some shops these roles might combine and overlap into the responsibilities of one or two people.

Outside of day-to-day machine operations, there is also the Manufacturing Engineer on staff. In a new shop setup, this individual typically establishes systems and determines an ideal manufacturing process. For existing setups, a Manufacturing Engineer will monitor equipment and product quality while handling other managerial tasks. We have John T. Parsons to thank for introducing a punch card method to program and automate machinery. John Parsons with an experimental NC machine. Image courtesy of Cms Industries.

From there the world of CNC machining started to take off. The idea was to incentive companies to adopt the new technology into their manufacturing process.The operation is similar to that of a commercial television set. In many cases, wire-frame models are quite adequate for two-dimensional representation. Try Fusion for free today. These coordinates can be treated together as a 1x1 matrix: Close tolerances must be held on the workpart.

This method is called manual data input, abbreviated MDI, and is appropriate only for relatively s1fuple Jobs where the order will not be repeated. This building-block approach is similar to the methods described in Section 6. Small-lot and batch production jobs represent the ideal situations for the application of NC.