Computer control programmers and operators use computer numerically controlled (CNC) machines to produce a wide variety of products, from automobile engines to computer keyboards. CNC machines operate by reading the code included in a computer-controlled module, which drives the machine tool and performs the functions of forming and shaping a part formerly done by machine operators. CNC machines include tools such as lathes, laser cutting machines, roll forms, press brakes and printing presses. CNC machines use the same techniques as many other mechanical manufacturing machines but are controlled by a central computer instead of a human operator or electric switchboard. Many old-fashioned machines can be retrofitted with a computer control, which can greatly improve the productivity of a machine. Computer control programmers and operators normally produce large quantities of one part, although they may produce small batches or one-of-a-kind items. These machines are most commonly used in metalworking industries where precision is imperative, because computers can be more accurate than humans in this work.
CNC programmers—also referred to as numerical tool and process control programmers—develop the programs that run the machine tools. They often review three-dimensional computer-aided/automated design (CAD) blueprints of a part and determine the sequence of events that will be needed to make the part. This may involve calculating where to cut or bore into the workpiece, how fast to feed the metal into the machine, and how much metal to remove.
Next, CNC programmers turn the planned machining operations into a set of instructions. These instructions are translated into a computer aided/automated manufacturing (CAM) program containing a set of commands for the machine to follow. On a CNC machine, commands normally are a series of numbers (hence, numerical control) that may describe where cuts should occur, where a roll should bend a piece, or the speed of the feed into the machine. After the program is developed, CNC programmers and operators check the programs to ensure that the machinery will function properly and that the output will meet specifications. Because a problem with the program could damage costly machinery and cutting tools or simply waste valuable time and materials, computer simulations may be used to check the program before a trial run. If errors are found, the program must be changed and retested until the problem is resolved. In addition, growing connectivity between CAD/CAM software and CNC machine tools is raising productivity by automatically translating designs into instructions for the computer controller on the machine tool. Many new machines take advantage of easy-to-use graphical user interface programs that use pictures and buttons, instead of long strings of a computer programming language. This improvement in usability has pushed many manufacturing companies to combine the jobs of CNC programmers and machine operators.
After the programming work is completed, CNC setup operators—also referred to as computer-controlled machine tool operators, metal and plastic—set up the machine for the job. They download the program into the machine, load the proper tools into the machine, position the workpiece on the CNC machine tool—spindle, lathe, milling machine, or other machine—and then start the machine. During the test run of a new program, the setup operator, who may also have some programming skills, or the CNC programmer closely monitors the machine for signs of problems, such as a vibrating work piece, the breakage of cutting tools, or an out-of-specification final product. If a problem is detected, a setup operator or CNC programmer will modify the program using the control module to eliminate the problems or to improve the speed and accuracy of the program.
Once a program is completed, the operation of the CNC machine may move from the more experienced setup operator to a less-skilled machine operator. Operators load workpieces and tools into a machine, press the start button, monitor the machine for problems, and measure the parts produced to check that they match specifications. If they encounter a problem that requires modification to the cutting program, they shut down the machine and wait for a more experienced CNC setup operator to fix the problem. Many CNC operators start at this basic level and gradually perform more setup tasks as they gain experience.
Regardless of skill level, all CNC operators detect some problems by listening for specific sounds—for example, a dull cutting tool that needs changing or excessive vibration. Machine tools rotate at high speeds, which can create problems with harmonic vibrations in the workpiece. Vibrations cause the machine tools to make minor cutting errors, hurting the quality of the product. Operators listen for vibrations and then adjust the cutting speed to compensate. For common errors in the machine, programmers write code that displays an error code to help operators, who are expected to make minor repairs, and machine mechanics fix a problem quickly. CNC operators also ensure that the workpiece is being properly lubricated and cooled, since the machining of metal products generates a significant amount of heat.
Since CNC machines can operate with limited input from the operator, a single operator may monitor several machines simultaneously. Typically, an operator might monitor two machines cutting relatively simple parts from softer materials, while devoting most of his or her attention to a third machine cutting a much more difficult part from hard metal, such as stainless steel. Operators are often expected to carefully schedule their work so that all of the machines are always operating.
Most machine shops are clean, well lit, and ventilated. Most modern CNC machines are partially or totally enclosed, minimizing the exposure of workers to noise, debris, and the lubricants used to cool workpieces during machining. People working in this occupation report fewer injuries than most other manufacturing jobs; nevertheless, working around machine tools can be noisy and presents certain dangers, and workers must follow safety precautions to minimize injuries. Computer-controlled machine tool operators, metal and plastic, wear protective equipment, such as safety glasses to shield against bits of flying metal and earplugs to dampen machinery noise. They also must exercise caution when handling hazardous coolants and lubricants. The job requires stamina, because operators stand most of the day and, at times, may need to lift moderately heavy workpieces. Numerical tool and process control programmers work on desktop computers that may be in offices or on the shop floor. The office areas usually are clean, well lit, and free of machine noise. On the shop floor, CNC programmers encounter the same hazards and exercise the same safety precautions as do CNC operators. Many computer control programmers and operators work a 40-hour week. CNC operators increasingly work evening and weekend shifts as companies justify investments in more expensive machinery by extending hours of operation. Overtime is common during peak production periods.
Education & Training Required
The amount and type of education and training needed depends on the type of job. Entry-level CNC machine operators may need at least a few months of on-the-job training to reach proficiency. Setup operators and programmers, however, may need years of experience or formal training to write or modify programs. Programmers and operators can receive their training in various ways—in apprenticeship programs, informally on the job, and in secondary, vocational, or postsecondary schools. A growing number of computer control programmers and more skilled operators receive their formal training from community or technical colleges. For some specialized types of programming, such as that needed to produce complex parts for the aerospace or shipbuilding industries, employers may prefer individuals with a degree in engineering.
For those interested in becoming computer control programmers or operators, high school or vocational school courses in mathematics (trigonometry and algebra), blueprint reading, computer programming, metalworking, and drafting are recommended. Apprenticeship programs consist of shop training and related classroom instruction. In shop training, apprentices learn filing, handtapping, and dowel fitting, as well as the operation of various machine tools. Classroom instruction includes math, physics, programming, blueprint reading, CAD software, safety, and shop practices. Skilled computer control programmers and operators need an understanding of the machining process, including the complex physics that occur at the cutting point. Thus, most training programs teach CNC operators and programmers to perform operations on manual machines prior to operating CNC machines.
As new technology is introduced, computer control programmers and operators normally receive additional training to update their skills. This training usually is provided by a representative of the equipment manufacturer or a local technical school. Many employers offer tuition reimbursement for job-related courses.
Other Skills Required
Employers prefer to hire workers who have a basic knowledge of computers and electronics and experience with machine tools. In fact, many entrants to these occupations have experience working as machine setters, operators, and tenders or machinists. Persons interested in becoming computer control programmers or operators should be mechanically inclined and able to work independently and do highly accurate work.
To boost the skill level of all metalworkers and to create a more uniform standard of competency, a number of training facilities and colleges have formed certification programs. Employers may pay for training and certification tests after hiring an entry-level worker.
How to Advance
Computer control programmers and operators can advance in several ways. Experienced CNC operators may become CNC programmers or machinery mechanics, and some are promoted to supervisory or administrative positions in their firms. Some highly skilled workers move into tool and die making, and a few open their own shops.
Despite the projected increase in employment, applicants are expected to face competition for jobs, as there are more trained workers than available jobs.
Median hourly wages of computer-controlled machine tool operators, metal and plastic, is $26.03. The middle 50 percent earned between $22.83 and $29.45. Many employers, especially those with formal apprenticeship programs, offer tuition assistance for training classes.