Evolution of computer numerical control machines and technology

History of CNC (Computer Numerical Control)

CNC Machines and How They Work

Computer-Aided Design

Future of CNC Machines

Spider-like CNC Machine

Laser Technology-based Micromachining

SSD technologies

Robotics Applications

This research paper will trace the history of Computer Controlled Machines from their inception to current sophistication levels. We shall also delve into their usage and benefits in various industries. The paper heavily references industry specific research from relevant eras to chronicle the evolution of CNC uses.

Rapid increases in the power of semiconductors and reductions in their costs made it possible to produce small, very powerful, relatively cheap minicomputers that could be used to control machine tools. The resulting computer-controlled machine tools (CNC) with a computer built into the machine tool allow for programming and editing by operators. In contrast, the hard-wired NC machine tools they replaced required programmers to produce and edit programs in offices away from the shop floor.

Chapter Two - Methodology

As automated equipment such as CNC machine tools comes into more widespread use, there is an increasing need for proper maintenance to ensure that the equipment fulfills its potential for economic production of high-quality goods. Kaplinsky (1984, p. 137) suggested that the maintenance of high-technology automated equipment had been de-skilled through the use of printed circuit board replacement procedures. If an automatic diagnostic system can signal the location of the faulty board, the maintenance task can be reduced to simply replacing the faulty board with a new one and either discarding the faulty board or sending it to a specialized department for analysis and repair.

Fig. 1.1

Research in both the United Kingdom (Senker et al., 1981; Cross, 1984) and the United States (Small, 2003) casts doubt on this de-skilling scenario. Certain maintenance tasks-in particular, the replacement of printed circuit boards -- do, indeed, require little skill. But the maintenance of high-technology manufacturing systems more typically requires the ability to diagnose faults efficiently and rapidly that are not so simply identified. Specifically, defects are often concealed within hydraulic or mechanical subsystems. Repair and maintenance people working with automated equipment require less intimate knowledge of a single process or task, but they need a general knowledge of more tasks (Lester, 2008).

Computer-Aided Design

In Britain until the 1940s, the aspiring apprentice tried to get into the drawing office because it offered the terms and conditions of white-collar employment with good chances of promotion. Many "draftsmen" (male drafters) without University degrees gained access to professional and managerial careers by achieving technical qualifications through part-time study. Traditionally, in Britain, drafters completing their apprenticeships started work as detail drafters, progressed to more complex drawing work, and finally to design work.

By the 1960s, however, drawing office employment had become less attractive for two principal reasons. First, improved conditions of service on the shop floor and lower pay differentials offered craft workers benefits comparable to those of drafters. Second and more important, easier access to higher education increased competition for the professional and management jobs to which drafters had previously aspired. University-educated engineers bypassed the drawing office and entered the engineering hierarchy as junior professionals, while drafters languished in the drawing office (Flowers, 2006).

Michael Cooley (1972) has suggested that the drawing office has been downgraded in importance as a result of the finer division of labor in engineering that began in the 1930s. He described how the creative design element had become increasingly separated from the work of executing drawings. The fragmentation of shop floor jobs was, according to Cooley, paralleled by fragmentation of the job of the designer/drafter. Until the 1930s, drafters in Britain were responsible for designing a component, stress testing it, selecting materials for it, writing the specifications, and liaising with the shop floor and customers. But starting in the 1930s, these functions were progressively broken down into separate jobs and taken over by various specialists, such as stress testers, metallurgists, tribologists, methods and planning engineers, and customer liaison engineers, leaving drafters with only the job of drawing (3D Systems Corporation, 2001).

In effect, in the Britain of the 1930s, drafters filled a general-purpose professional engineering and design role. As the whole process of design became more complex, the role of the drafter was split into higher functions -- the specialists Cooley mentions, together with University graduate engineer designers -- and lower level jobs -- principally, drafters and support technicians. Cooley criticized the whole process of specialization and division of labor, which he termed fragmentation, on which the industrial development of the past two hundred years has been based. He writes nostalgically of the millwright who "was capable of repairing any machine in the plant in which he worked. He could predict the failure rate of bearings, select the material for new ones, and in most cases manufacture them himself." By contrast, he argued, "CAD tends to de-skill the designer, subordinate the designer to the machine and give rise to alienation. Indeed, most computerized design environments begin to display those elements which are regarded as constituting industrial alienation, in particular powerlessness, meaninglessness, and loss of self and normality" ( 1987, p. 40).

Chapter Three -- Results and Findings

Evidence supporting such views was provided by Chris Baldry and Anne Connolly on the basis of a study of seven leading CAD users in Scotland in the early 1980s (Lester, 2008). They found that much CAD work was repetitive and routine, involving details and enlargements of existing designs. Groups of drafters often worked on the same drawing, and few operators had the satisfaction of producing a complete drawing themselves. Operators had lost some elements of control over their work. The CAD system produced all drawing, labeling, and dimensioning in a standard format. Indeed, standardization of design is often a direct consequence of CAD use because CAD works most effectively if a library of standard parts and components is constructed in the computer's memory. Similarly, Kaplinsky (1982, p. 110) found that operators and management agreed that CAD reduced the skill component in drafting because it removed the craft elements associated with individually tailored layouts and lettering.

McLoughlin (1989), however, challenged Baldry and Connolly's findings on the basis of his own more recent case studies. While Baldry, Connolly, and Kaplinsky had cited the loss of manual craft skills in drawing as evidence of de-skilling, McLoughlin found that the new mental skills needed to use CAD usually compensated for the loss of manual skills. In response to the standardization argument, he pointed out that design is, in essence, a three-stage iterative process of basic conceptualization, analysis of design options, and detailed design and drawing. Most of the CAD systems in use in Britain are drafting systems, essentially electronic drawing boards serving only the third phase. They enable users to manipulate two-dimensional drawings and annotate them. CAD systems are "shape processors" analogous to word processors, which aid writers but do not reduce the need for writing skills. In addition, McLoughlin notes the increasing use of modeling systems that support more directly the earlier, more creative phases. Computer models act as malleable databases from which drawings can be extracted and displayed. They allow designers to consider several design options in some detail before deciding on a final design. They can also provide data for downstream activities such as production and thereby eliminate a great deal of routine work in recopying drawings. According to McLoughlin, "Drawing by conventional means utilizes a number of craft mental skills in manipulating the pencil, and involves a direct relationship between the thought of a user to 'draw a line' and the act of drawing." When CAD is used, "The craft skills used in actual drawing are eliminated as lines of perfect quality and weight are drawn automatically by the system. The relationship between the user and the drawing thus becomes more indirect and abstract, requiring the exercise of mental skills in understanding the capabilities of the system and in selecting appropriate routines from the menu."

Our own interviews with a small sample of CAD users tended-with some exceptions -- to support McLoughlin's findings (Watson & Petre, 2000). One user commented that CAD made his work more routine, and some complained that CAD took away the satisfaction that could be derived from producing a good drawing. The more common view, however, was that CAD increased the skills required of the designer or drafter. The most common types of positive comment made about CAD were that it made the work more interesting and less routine, and that job prospects were liable to be better in companies using CAD. For example, one CAD user commented:

Working on CAD removes a lot of the tedium of the board but also offers more avenues for being creative. It feels like you are involved with a project rather than a drawing. Creativity is improved with the greater freedom offered through, for example, the ease of iteration and change, but it is limited by the level of expertise you can develop and the poor level of system development.

Another changed his unfavorable first impressions of CAD:

I thought it took away a drafter's skills. But, after learning to use CAD, I realized that the CAD "only draws pictures.' It does not take the skills of an engineer away; it enhances them. It does not take drafting skills away. You need drafting skills to produce good work on CAD. Advantages of CAD are that it is quick and you can do more complicated things. . . . CAD makes life easier. It would be a real pain to go back to the old ways of doing things.

CAD only began to affect British engineering firms in the late 1970s and early 1980s, and did not become really significant in British design and drawing offices until the mid- 1980s. Undoubtedly, engineering and design work has become much more specialized. It is doubtful, however, that the net result has been or will be de-skilling: There appears to be little evidence for Cooley's contention that CAD has de-skilled drawing and design work and would reduce the status of the drawing office still further. Indeed, our research in the early 1980s suggested that the "glamour" of CAD was likely to restore the status of the design function and to attract University graduates into design work (Meissner, 2006).

Chapter Four - Discussions

By the mid-1970s the introduction of all the major components for highly integrated, computer-driven manufacturing was well underway. Data collection, inventory control, production planning, CAE, and CAD/CAM applications were now the norm. Numerical control tools were the other components that linked planning to actual production of goods. They were widespread by the 1980s and virtually ubiquitous in the 1990s. The important development in this second period (1960s and 1970s) was the injection of computing into machining tools.

As noted before in this thesis, the earliest tools were highly inflexible, but with the introduction of microprocessor-driven tools in the early 1970s, now called computer numerical control (CNC), machines could be quickly instructed to change their operations. That new functionality drove down labor costs, increased flexibility, and shortened the time it took to cut and bend metal, for example. Mass producers could increase the variety of products they made without building new plants. By the end of the 1970s, these tools had sensing capabilities, which meant that they could alter operations in real time, an essential requirement for the effective use, say, of robots. The availability of sensing devices drove up the sale of robotic devices; in 1981 more were sold than in all previous years combined. With such capabilities in NC equipment, manufacturing firms could extend their automation sufficiently to begin creating flexible manufacturing systems (FMS), the basic new innovation evident in the late 1980s and through the 1990s. Computers could be used to design products, develop production schedules, and then instruct machines to make them. Logistics systems could then physically transport finished goods to warehouses or load them on trucks.

As recently as the early 1960s, manufacturing executives complained that NC machining tools were too expensive and cumbersome. The situation was unimpressive. Roy A. Lindberg, a mechanical engineering professor at the University of Wisconsin, minced no words when he criticized the technology: "No manufacturer can produce an item of any consequence without knowing that it may be obsolete tomorrow." Progress in providing enhanced capabilities was slow: "The metalworking industry has been content to take automation in smaller steps" (Chandler, 1977). Standalone NC equipment at the time was made to perform screw operations, and provide electric, air, and hydraulic controls, as well as increasing amounts of tape control (which could be driven by computers since tape was a form of output and a source of programming instructions), while multiple-machine automation was in its infancy. One manufacturing expert, as late as 1973 (after the invention of the microprocessor but just before its wide application in NC tools) prognosticated that NC tools would eventually displace older technologies, although not immediately:

There are large sectors of the industrial world in which NC is basically inapplicable, and other sectors in which NC may be applicable but not economically justifiable. As a result, we can expect that NC technology will coexist with older technologies for many years to come. In fact, when these older technologies are closely examined they turn out to be themselves layered composites of still older technologies (Chandler, 1977).

This is exactly what happened. The factory of the early twenty-first century is an impressive collection of computers and robots, but the journey there has been slow and evolutionary. Numerical control was one of the gating factors for the rate of evolution to more integrated manufacturing. But slowly this new generation of equipment came online during the second half of the 1970s. In addition to being able to send instructions to individual machines, the activities of multiple devices could now be controlled and synchronized. Monitoring functions also became possible by the late 1970s. In 1981, Allen-Bradley had linked these various capabilities together, making possible updated factory operations plans. With that kind of development, processes for flexible manufacturing could be created. In effect, a majority of production steps could now be programmed in advance, started, and then controlled by computers. By having computer chips in all major factory equipment, one could communicate with machines and have them transfer data about what they were doing to each other. Two professors, experts on NC equipment and manufacturing, wrote at the start of the 1980s, after the arrival of the new generation of equipment, that "numerical control is one of the most important basic innovation of our century & #8230;it has gone far beyond the original cutting-machine tools and has revolutionized manufacturing and other areas of human productive activity" (Brown, 2009). Over 100 new types of NC equipment were reaching the market by that time.

Improvements in the ability to program and maintain this equipment in the 1980s increased the variety of uses (and hence demand) for such technology around the world, including in the United States. Traditional concerns on the part of manufacturing companies still influenced their decisions on when to acquire NC equipment: the need to lower costs of inventory, improve and maintain quality control, and operate with shorter production cycles. Economist Roberto Mazzoleni observed that "during the 1980s, the competitive strategies of U.S., European, and Japanese companies were characterized by an increasing quest for manufacturing flexibility and a movement toward small- and medium-batch production runs," which led to increased demands for this kind of technology. This execution of the strategy caused firms around the world to install applications for jig boring, gear cutting, laser cutting, electro discharges, and grinding for special purpose jobs; development of systems for rotational and prismatic parts for general purpose work; and creation of special purpose systems to support flexible transfer lines and FMS with specialized equipment. Machine and turning centers within factories also were equipped. Flexible manufacturing factories increased from 8 in the United States in 1975 to 28 in 1980. In 1995, there were approximately. In that year, Japan claimed to have 166, Western Europe 208. The point is not so much that one nation or another was ahead but rather that manufacturing had changed extensively. Large American factories tended to rely on more inflexible transfer line approaches, but even these became more flexible during the 1980s (Schroff Development Corporation, 2011). One study, comparing the number of product variants processed by FMS factories in different countries, turned up the fact that in the mid-1980s 41% of those U.S. factories that claimed to have FMS could handle up to 10 variants, another 22% could handle up to 50 variants, and another 13% up to 100 variants. This compared very closely to the Japanese production capability, whereas Western European factories had less flexibility.

Future of CNC Machines

CNC or "computer numerical controlled" machines are complicated metalworking gear that can make complex parts essential in modern machinery. Rising fast with the leaps in computer technology and sophistication, CNCs can be seen performing jobs such as lathes, milling equipment, laser scissors, abrasive jet shears, punch presses, press brakes, and various other industrial gear. The CNC term is used to define a big group of these equipment that use computer logic to organize movements and carry out the metalworking.

1. Spider-like CNC Machine

The potential and prospective future of CNC machines is expanding massively. One design under design is a spider-like machine which a spindle that is balanced by six perfectly set telescoping ballscrew struts. The struts are similar to the gears in a traditional machine, except they are circular and with the ballscrew assemblage in the middle (Lester, 2008). The movements of the spindle are carried out by an advanced computer calculating millions of mathematical formulas to guarantee accurate part functioning.

Even though, this machine can cost several million dollars to build and utilizing high level, R&D mathematics, this apparatus assures performances that were in the past unthinkable functions and uses in metal machining. Progress in processor chips and artificial intelligence will make CNC machines in the future quicker and easier to control. This will however not come reasonably, and the cost of complicated CNC machines will be further than the reach of many firms. It might, on the other hand, decrease the costs of the fundamental CNC machines carrying out the traditional three-axis movements.

2. Laser Technology-based Micromachining

In plain words laser technology core micromachining is the slicing, drilling, tearing and skiving a variety of kinds of substances such as glass, plastics and particular types of elements. The accuracy of laser technology is unrivaled and so is the pace at which it is carried out. The technology has non-staff communication with the material as a result is an effortlessness of carrying out the process. Laser micromachining is more often than not used in creating purposely small three dimensional equipments.

The most distinguished area of laser micromachining is the medical equipments business. High precision apparatus is typically made by the use of this machinery such as angioplasty devices. The further extremely complex and very sophisticated is the utilization of laser micromachining when it comes to management of cardiac troubles (Schroff Development Corporation, 2011).

SSD technologies

The CNC industry currently is not motivating developments that are explicit to their requirements. To a certain extent, they chase the general-purpose computing technology and take on inexpensive results applicable to PCs. The utilization of mass storage at the mechanism itself is not accepted because of the shaking and mechanical tremors of the equipment. For security, as the CNC computer continually trails its spot, pace and direction of motion. If the procedure is intermittent, this data must be able to be safely stored.

As end-consumer applications of SSDs (otherwise known as flash drives) increases, cnc applications will go after that inclination for their memory requirements, though the subject of the inadequate number of rewrites is yet an accessible subject (Lester, 2008). Optional SSD technologies, though infinitely suitable on technological basis, are not at this stage cost effective.

4. Robotics Applications

Although robots can be considered part of the discussion about the adoption of NC tools, they are so unique in the minds of the proverbial "average person" that they deserve separate, if brief, comment. Hundreds of movies and novels have portrayed the robot as a humanlike creature with little or no feelings, made of metal, and often evil in purpose. That is fiction; reality was a far more primitive class of devices, called industrial robots (IRs). These are designed to do a few highly specialized activities faster, more accurately, or less expensively than humans. Manufacturing companies deployed the majority of the machines available in the 1970s and 1980s. They often looked like huge arms protruding out of metal boxes; some were on wheels, others on tracks, and a few were bolted to the floor in production settings or suspended from ceilings. In 1959, Joseph Engelberger joined an early robot designer, George Devol, to develop the first commercial robotic products. Their initial prototype, the Unimate, made it possible for them to establish a company that made robots, Unimation, Inc. Over the years various other firms entered the business (Yoffie, 1997). After the invention of the microprocessor, one could build programmable robots, equip them with sensors, and effectively command them to perform and change work. They consisted of three components: a mechanical manipulator, doing the tasks requested of it; a power supply; and the computer like part of the machine, known as the control system (Lester, 2008).

The IRs were used to move materials, parts, and tools. They performed repetitious tasks, such as the 2,000 to 3,000 spot welding required to put together an automobile; spray-painted industrial equipment and vehicles; and inspected paint jobs and the physical appearances of many products to ensure uniformity. In the 1970s, a few robots were being installed; by the end of the decade they were programmable. In the 1980s they were generally of eight types: manual manipulators, sequence-control devices, playback robots, NC-controlled machines, "intelligent" robots, sensory-controlled units, adaptive controlled robots, and learning controlled robots. But they essentially performed applications that required them to "pick and place," and as so often happened with the emergence of new technologies, American enthusiasm exceeded the capabilities of the machines. For instance, Business Week in early 1981 published a detailed survey of IRs, reporting on the exuberance of American manufacturing executives who were looking forward to embracing this new technology: "Just owning a robot is clearly not enough. Now, the story goes, no self-respecting company wants to be caught without its own line of robots" (Flowers, 2006).

Fig. 1.2

Robots were initially most popular in the Automotive Industry in the late 1970s and early 1980s, where they could perform highly specialized, repetitive, precision work cost-effectively. In the 1980s, Japanese manufacturers of consumer electronics began to use a whole new generation of robotic technology. Robots, however, have not been as widely disbursed into manufacturing plants as one might have thought because they are expensive and instructing them was complex all through the 1980s and into the 1990s. In the 1970s and again in the 1980s, they were not always as reliable as required. In short, they had not yet reached the level of sophistication needed to become fully integrated with existing NC-based technologies already installed in factories. One expert on IT in the early 1980s described how best to use robots:

Industrial robots are not stand-alone devices which can be bought off-the-shelf and plugged in immediately to a chosen application. The robot forms only part of an overall system, even in the simplest applications such as die-casting, and the interface consists primarily of interlocks that ensure the different devices mesh together correctly [and] the whole system operates safely.

Fig. 1.3

Chapter Five - Conclusions

Applications continued to change. Mass customization on the shop floor translated into flexible manufacturing systems (FMS), making rapid changes in production possible. Increasingly, a concept called computer-integrated manufacturing (CIM) affected how various activities and machines were more closely integrated by using software to coordinate these initiatives. As one expert described it:

CIM combines flexible automation, CAD/CAM systems, and management information systems to build integrated production systems that cover the complete operations of a manufacturing firm, including purchasing, logistics, maintenance, engineering, and business operations. CIM emphasizes horizontal links between different organizational units of a firm and profits the possibility of sharing data and computing resources, making it possible to break the traditional institutional barriers between departments and create flexible functional groups to perform tasks more speedily and efficiently.