Consider the parts of a toaster the metal or plastic housing or the lever that lowers the toast, for example. These parts, and many other metal and plastic products, are produced by metal and plastics-working machine operators. In fact, manual and numerical control machine tool operators in the metalworking and plastics industries play a major part in producing most of the consumer products on which we rely daily.
These workers can be separated into two groups: Those who set up machines for operation and those who tend the machines during production. Setup workers prepare the machines prior to production and may adjust the machinery during operation. Operators and tenders, on the other hand, primarily monitor the machinery during operation, sometimes loading or unloading the machine or making minor adjustments to the controls. Many workers do both set up and operate the equipment. Because the set-up process requires an understanding of the entire production process, setters usually have more training and are more highly skilled than those who simply operate or tend the machinery.
Setters, operators, tenders, and set-up operators are usually identified by the type of machine with which they work. Some examples of specific titles are screw machine operator, plastics-molding machine setup operator, and lathe tender. Although some workers specialize in one or two types of machinery, many are trained to set up or operate a variety of machines. Job duties usually vary based on the size of the firm as well as on the type of machine being operated.
Metalworking machine setters and operators set up and tend machines that cut and form all types of metal parts. Traditionally, setup workers plan and set up the sequence of operations according to blueprints, layouts, or other instructions. They adjust speed, feed, and other controls, choose the proper coolants and lubricants, and select the instruments or tools for each operation. Using micrometers, gauges, and other precision measuring instruments, they may compare the completed work with the tolerance limits stated in the specifications.
Although there are many different types of metalworking machine tools that require specific knowledge and skills, most operators perform similar tasks. Whether tending grinding machines that remove excess material from the surface of machined products or presses that extrude metal through a die to form wire, operators usually perform simple, repetitive operations that can be learned quickly. Typically, these workers place metal stock in a machine on which the operating specifications have already been set. They may watch one or more machines and make minor adjustments according to their instructions. Regardless of the type of machine they operate, machine tenders usually depend on skilled setup workers for major adjustments when the machines are not functioning properly.
Plastics working machine operators set up and tend machines that transform plastic compounds chemical based products that can be produced in powder, pellet, or syrup form into a wide variety of consumer goods such as toys, tubing, and auto parts. These products are produced by various methods, of which injection molding is the most common. The injection molding machine heats a plastic compound and forces it into a mold. After the part has cooled and hardened, the mold opens and the part is released. Many common kitchen products are produced using this method. To produce long parts such as pipes or window frames, on the other hand, an extruding machine is usually employed. These machines force a plastic compound through a die that contains an opening of the desired shape of the final product. Yet another type of plastics working technique is blow molding. Blow-molding machines force hot air into a mold which contains a plastic tube. As the air moves into the mold, the plastic tube is inflated to the shape of the mold and a plastic container is formed. The familiar 2-liter soft drink bottles are produced using this method.
Regardless of the process used, plastics-working machine operators check the materials feed, the temperature and pressure of the machine, and the rate at which the product hardens. Depending on the type of equipment in use, they may also load material into the machine, make minor adjustments to the machinery, or unload and inspect the finished products. Plastics-working machine operators also remove clogged material from molds or dies. Because molds and dies are quite costly, operators must exercise proper care to avoid damaging them.
Metal and plastics-working machine operators are increasingly being called upon to work with numerically controlled (NC) equipment. These machine tools have two major components: An electronic controller and a machine tool. Almost all NC machines today are computer numerically controlled (CNC), which means that the controllers are computers. The controller directs the mechanisms of the machine tool through the positioning and machining described in the program or instructions for the job. A program could contain, for example, commands that cause the controller to move a drill bit to certain spots on a workpiece and drill a hole at each spot.
Each type of CNC machine tool, such as a milling machine, a lathe, or a punch press, performs a specific task. A part may be worked on by several machines before it is finished. CNC machines are often used in computer-integrated manufacturing (CIM) systems. In these systems, automated material handling equipment moves workpieces through a series of work stations where machining processes are computer numerically controlled. In some cases, the workpiece is stationary and the tools change automatically. Although the machining is done automatically, numerically controlled machine tools must be set up and used properly in order to obtain the maximum benefit from their use. These tasks are the responsibility of numerical-control machine-tool operators or, in some instances, machinists. (See the statement on machinists and tool programmers elsewhere in the Handbook.)
Like the duties of manual metal and plastics machine operators, the duties of numerical-control machine-tool operators vary. In some shops, operators tend just one machine. More likely, however, they might tend a number of machines or do some programming. As a result, the skill requirements of these workers vary from job to job. Although there are many variations in operators' duties, they generally involve many of the tasks described below.
Working from given instructions, operators load programs that are usually stored on floppy disks into the controller. They also securely position the workpiece, attach the necessary tools, and check the coolants and lubricants. Many numerically controlled machines are equipped with automatic tool changers, so operators may also load several tools in the proper sequence. In addition, heat generated by machining could damage the cutting tools and the part being machined, so operators must ensure that the proper coolants and lubricants are being used. This entire process may require a few minutes or several hours, depending on the size of the workpiece and the complexity of the job.
A new program must be debugged, or adjusted, to obtain the desired results. If the tool moves to the wrong position or makes a cut that is too deep, for example, the program must be changed so that the job is done properly. Sometimes an NC operator will debug programs, but more often a machinist or tool programmer will perform this function. (See the statement on machinists and tool programmers elsewhere in the Handbook.) A new generation of machine tool technology called direct numerical control allows operators to make changes to the program and enter new specifications via menu-driven mini computers on the shop floor.
Because numerically controlled machine tools are very expensive, an important duty of operators is to monitor the machinery to prevent situations that could result in costly damage to the cutting tools or other parts. The extent to which the operator performs this function depends on the type of job as well as the type of equipment being used. Some numerically controlled machine tools automatically monitor and adjust machining operations. When the job has been properly set up and the program has been checked, the operator may only need to monitor the machine as it operates. These operators often set up and monitor more than one machine. Other jobs require frequent loading and unloading, tool changing, or programming. Operators may check the finished part using micrometers, gauges, or other precision inspection equipment to ensure that it meets specifications. Increasingly, however, this function is being performed by numerically controlled machine tools that are able to inspect products as they are being produced.
CNC machines are changing the Nature of the Work that machine setters and operators perform. For example, computer-controlled machines simplify setups by using formerly tested computer programs for new workpieces. If a workpiece is similar to one previously produced, small adjustments can be made to the old program instead of developing a new program from scratch. Also, operators of this equipment have less physical interaction with the machinery or materials. They primarily act as troubleshooters, monitoring machines on which the loading, forming, and unloading processes are often controlled by computers.
Automated machinery has increased the productivity of many machine operators.
Most metalworking and plastics-working machine operators work in areas that are clean, well lit, and well ventilated. Regardless of setting, all of these workers operate powerful, high-speed machines that can be dangerous if strict safety rules are not observed. Most operators wear protective equipment such as safety glasses and earplugs to protect against flying particles of metal or plastic and noise from the machines. Other required equipment varies by work setting and by machine. For example, workers in the plastics industry who work near materials that emit dangerous fumes or dust must wear face masks or self-contained breathing apparatuses.
Most metal and plastics working machine operators work a 40-hour week, but overtime is common during periods of increased production. The industries in which metal and plastics workers are concentrated average 3 or 4 hours of overtime per week. Because many metalworking and plastics working shops operate more than one shift daily, some operators work nights and weekends.
The work requires stamina because operators are on their feet much of the day and may do moderately heavy lifting. Approximately 35-40 percent of these workers are union members; the metalworking industries have a higher rate of unionization than the plastics industry.
Metalworking and plastics-working machine operators held about 1,378,000 jobs in 1992. Of these, 1,305,000 were manual machine operators, and 73,000 were NC machine operators. Eight out of every 10 of these workers are found in five industries: Fabricated metal products, industrial machinery and equipment, miscellaneous plastic products, transportation equipment, and primary metals. Table 1 shows the distribution of employment of metal and plastics-working machine operators by detailed occupation.
Table 1. Distribution of Metal and plastics-working machine operators by detailed occupation, 1992
Occupation Percent
Machine tool cutting and forming machine setters and operators....49
Molding machine setters and operators.............................14
Sheetmetal workers and duct installers........................... 8
Combination machine tool setters and operators................... 7
Numerical control machine operators.............................. 5
Plating machine setters and operators............................ 4
Metal fabricators, structural metal products..................... 3
Heaters and heat treating machine setters and operators.......... 2
SOURCE: Bureau of Labor Statistics
Most metal and plastics-working machine operators learn their skills on the job. Trainees begin by observing and assisting experienced workers, often in formal training programs. Under supervision they may supply material, start and stop the machine, or remove finished products from the machine. As part of their training they advance to more difficult tasks like adjusting feed speeds, changing cutting tools, or inspecting a finished product for defects. Eventually they become responsibile for their own machine or machines.
The complexity of equipment largely determines the time required to become an operator. Most operators learn the basic machine operations and functions in a few weeks, but they may need several years to become a skilled operator or to advance to the more highly skilled job of setup operator.
Although setup operators perform many of the same tasks as skilled machine operators, they also need to have a thorough knowledge of the machinery and of the products being produced. Setup operators often study blueprints, plan the sequence of work, make the first production run, and determine which adjustments need to be made. Strong analytical abilities are particularly important to perform this job. Some companies have formal training programs for setup operators that combine classroom instruction with on-the-job training.
CNC machine tool operators undergo similar training. Working under a supervisor or an experienced operator, trainees learn to set up and run one or more kinds of numerically controlled machine tools. Trainees usually learn the basics of their jobs within a few months. However, the length of the training period varies with the number and complexity of the machine tools the operator will run and with the individual's ability. If the employer expects operators to write programs, trainees may attend programming courses offered by machine tool manufacturers or technical schools. These courses usually last a couple of weeks.
Although no special education is required for most operating jobs, employers prefer to hire applicants with good basic skills. Many require employees to have a high school education and to read, write, and speak English. This is especially true for numerical control machine operators, who may need to be retrained often in order to learn to operate new equipment. Because machinery is becoming more complex and shop floor organization is changing, employers increasingly look for persons with good communication and interpersonal skills. Mechanical aptitude, manual dexterity, and experience working with machinery are also pluses. Those interested in becoming a metal or plastics-working machine operator can improve their employment opportunities by completing high school courses in shop, mathematics, and blueprint reading and by gaining a working knowledge of the properties of metals and plastics.
Advancement for operators usually takes the form of higher pay, although there are some limited opportunities for operators to advance to new positions as well. For example, they can become multiple machine operators, setup operators, or trainees for the more highly skilled positions of machinist or tool and die maker. Manual machine operators can move on to CNC equipment when it is introduced into their establishments. Some setup workers and CNC operators may advance to supervisory positions. CNC operators who have substantial training in numerical control programming may advance to the higher paying job of tool programmer. (See statements on machinists and tool programmers, and tool and die makers found elsewhere in the Handbook.)
Overall employment of metal and plastics-working machine operators is expected to decline through the year 2005. This decline is likely to affect metalworking machine operators more than those working with plastics machines. In addition, setters and more highly skilled operators are more likely to be retained by firms than are semi-skilled operators and tenders. In spite of the overall employment decline, however, a large number of jobs will become available each year as current operators and setters transfer to other occupations or leave the labor force.
A major factor driving the employment decline is the increasing productivity resulting from computer-controlled equipment. In order to remain competitive, many firms are adopting this technology to improve quality and lower production costs. Computer-controlled equipment allows operators to simultaneously tend a greater number of machines and often makes setup easier, thereby reducing the amount of time setup workers spend on each machine. For these reasons, employment of CNC machine operators is expected to increase in the future despite the decline in machine operators as a whole. Lower-skilled positions like manual machine tool operators and tenders are more likely to be eliminated by increasing automation than those of setters and set up operators, whose higher skills are more in demand and whose job functions are less easily automated.
The demand for metal and plastics machine operators largely mirrors the demand for the parts they produce. In recent years, plastic products have been substituted for metal goods in many consumer and manufacturing products. Although the rate of substitution may slow in the future, this process is likely to continue and should result in a relatively stronger demand for machine operators in plastics than in metalworking. Both industries, however, face stiff foreign competition that is limiting the demand for domestically-produced parts. One way that larger U.S. producers have responded to this competition is by moving production operations to other countries in order to reduce labor costs. These moves are likely to continue and will further reduce employment opportunities for metal and plastics-working machine tool operators in the United States.
Workers with a thorough background in machine operations, exposure to a variety of machines, and a good working knowledge of the properties of metals and plastics will be best able to adjust to this changing environment. In addition, new shopfloor arrangements will reward workers with good basic mathematics and reading skills, good communication skills, flexibility, and the ability and willingness to learn new tasks. Those interested in working with CNC machine tools will most likely need to have a high school education and should be familiar with several types of machines and operating systems.
Median weekly earnings for most metal and plastics-working machine operators were $413 in 1992. The middle 50 percent earned between $300 and $536. The top 10 percent earned over $697 and the bottom 10 percent earned less than $236. Plastic molding machine operators earned somewhat less, about $359 a week. Numerical-control machine-tool operators earned between $450 and $500 a week in 1992, according to the limited data available.
Earnings of production workers vary considerably by industry, however. Average weekly wages for production workers in industries where employment of metal and plastics-working machine operators is concentrated are shown in the following tabulation.
Transportation equipment..........................................$633
Primary metals industries......................................... 590
Industrial machinery and equipment................................ 525
Fabricated metal products......................................... 475
Rubber and misc. plastics products................................ 433
Most machine operators receive standard benefits such as pension plans, vacation and sick leave, and retirement plans.
Workers in occupations closely related to metalworking and plastics-working machine occupations include machinists, tool and die makers, extruding and forming machine operators producing synthetic fibers, woodworking machine operators, and metal patternmakers. Numerical-control machine-tool operators may program CNC machines or alter existing programs, which are functions closely related to those performed by NC machine tool programmers.
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Reprinted with Permission of U. S. Department of Labor