Machinists use machine tools, such as lathes, milling machines, and
machining centers, to produce precision metal parts. Although they may
produce large quantities of one part, precision machinists often produce
small batches or one-of-a-kind items. They use their knowledge of the
working properties of metals and their skill with machine tools to plan
and carry out the operations needed to make machined products that meet
precise specifications.
Before they machine a part, machinists must carefully plan and
prepare the operation. These workers first review blueprints or written
specifications for a job. Next, they calculate where to cut or bore into
the workpiece (the piece of metal that is being shaped), how fast to
feed the metal into the machine, and how much metal to remove. They then
select tools and materials for the job, plan the sequence of cutting and
finishing operations, and mark the metal stock to show where cuts should
be made.
After this layout work is completed, machinists perform the
necessary machining operations. They position the metal stock on the
machine tool—drill press, lathe, milling machine, or other type of
machine—set the controls, and make the cuts. During the machining
process, they must constantly monitor the feed rate and speed of the
machine. Machinists also ensure that the workpiece is being properly
lubricated and cooled, because the machining of metal products generates
a significant amount of heat. The temperature of the workpiece is a key
concern because most metals expand when heated; machinists must adjust
the size of their cuts relative to the temperature. Some rare but
increasingly popular metals, such as titanium, are machined at extremely
high temperatures.
Machinists detect some problems by listening for specific
sounds—for example, a dull cutting tool or excessive vibration. Dull
cutting tools are removed and replaced. Cutting speeds are adjusted to
compensate for harmonic vibrations, which can decrease the accuracy of
cuts, particularly on newer high-speed spindles and lathes. After the
work is completed, machinists use both simple and highly sophisticated
measuring tools to check the accuracy of their work against blueprints.
Some machinists, often called production machinists, may produce
large quantities of one part, especially parts requiring the use of
complex operations and great precision. Many modern machine tools are
computer numerically controlled (CNC). Frequently, machinists work with
computer-control programmers to determine how the automated equipment
will cut a part. (See the statement on computer
control programmers and operators elsewhere in the Handbook.)
The programmer may determine the path of the cut, while the machinist
determines the type of cutting tool, the speed of the cutting tool, and
the feed rate. Because most machinists train in CNC programming, they
may write basic programs themselves and often modify programs in
response to problems encountered during test runs. After the production
process is designed, relatively simple and repetitive operations
normally are performed by machine setters, operators, and tenders. (See
the statement on machine setters, operators, and tenders—metal and
plastic, elsewhere in the Handbook.)
Some manufacturing techniques employ automated parts loaders,
automatic tool changers, and computer controls, allowing machine tools
to operate without anyone present. One production machinist, working 8
hours a day, might monitor equipment, replace worn cutting tools, check
the accuracy of parts being produced, and perform other tasks on several
CNC machines that operate 24 hours a day (lights-out manufacturing).
During lights-out manufacturing, a factory may need only a few
machinists to monitor the entire factory.
Other machinists do maintenance work—repairing or making new parts
for existing machinery. To repair a broken part, maintenance machinists
may refer to blueprints and perform the same machining operations that
were needed to create the original part.
Today, most machine shops are relatively clean, well lit, and
ventilated. Many computer-controlled machines are partially or totally
enclosed, minimizing the exposure of workers to noise, debris, and the
lubricants used to cool workpieces during machining. Nevertheless,
working around machine tools presents certain dangers, and workers must
follow safety precautions. Machinists 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, although many common water-based
lubricants present little hazard. The job requires stamina, because
machinists stand most of the day and, at times, may need to lift
moderately heavy workpieces. Modern factories extensively employ
autoloaders and overhead cranes, reducing heavy lifting.
Most machinists work a 40-hour week. Evening and weekend shifts are
becoming more common as companies justify investments in more expensive
machinery by extending hours of operation. However, this trend is
somewhat offset by the increasing use of lights-out manufacturing.
Overtime is common during peak production periods.
Machinists held about 387,000 jobs in 2002. Most machinists work in
small machining shops or in manufacturing industries, such as machinery
manufacturing and transportation equipment manufacturing (motor vehicle
parts and aerospace products and parts). Maintenance machinists work in
most industries that use production machinery.
Machinists train in apprenticeship programs, informally on the job,
and in high schools, vocational schools, or community or technical
colleges. Experience with machine tools is helpful. In fact, many
entrants previously have worked as machine setters, operators, or
tenders. Persons interested in becoming machinists should be
mechanically inclined, have good problem-solving abilities, be able to
work independently, and be able to do highly accurate work (tolerances
may reach 1/10,000th of an inch) that requires concentration and
physical effort.
High school or vocational school courses in mathematics (especially
trigonometry), blueprint reading, metalworking, and drafting are highly
recommended. Apprenticeship programs consist of shop training and
related classroom instruction lasting up to 4 years. In shop training,
apprentices work almost full time, and are supervised by an experienced
machinist while learning to operate various machine tools. Classroom
instruction includes math, physics, materials science, blueprint
reading, mechanical drawing, and quality and safety practices. In
addition, as machine shops have increased their use of
computer-controlled equipment, training in the operation and programming
of CNC machine tools has become essential. Apprenticeship classes are
taught in cooperation with local community or vocational colleges. A
growing number of machinists learn the trade through 2-year associate
degree programs at community or technical colleges. Graduates of these
programs still need significant on-the-job experience before they are
fully qualified.
To boost the skill level of machinists and to create a more uniform
standard of competency, a number of training facilities and colleges are
implementing curriculums that incorporate national skills standards
developed by the National Institute of Metalworking Skills (NIMS). After
completing such a curriculum and passing a performance requirement and
written exam, trainees are granted a NIMS credential, which provides
formal recognition of competency in a metalworking field. Completing a
recognized certification program provides a machinist with better career
opportunities.
As new automation is introduced, machinists 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. Some employers offer tuition reimbursement for
job-related courses.
Machinists can advance in several ways. Experienced machinists may
become CNC programmers, tool and die makers, or mold makers, or be
promoted to supervisory or administrative positions in their firms. A
few open their own shops.
Despite projected slower-than-average employment growth, job
opportunities for machinists should continue to be excellent. Many young
people with the necessary educational and personal qualifications needed
to obtain machining skills may prefer to attend college or may not wish
to enter production occupations. Therefore, the number of workers
obtaining the skills and knowledge necessary to fill machinist jobs is
expected to be less than the number of job openings arising each year
from employment growth and from the need to replace experienced
machinists who transfer to other occupations or retire.
Employment of machinists is expected to grow
more slowly than the average for all occupations over the 2002-12
period because of rising productivity among these workers. Machinists
will become more efficient as a result of the expanded use of and
improvements in technologies such as CNC machine tools, autoloaders, and
high-speed machining. This allows fewer machinists to accomplish the
same amount of work previously performed by more workers. Technology is
not expected to affect the employment of machinists as significantly as
that of most other production occupations, however, because machinists
monitor and maintain many automated systems. Due to modern production
techniques, employers prefer workers, such as machinists, who have a
wide range of skills and are capable of performing almost any task in a
machine shop.
Employment levels in this occupation are influenced by economic
cycles—as the demand for machined goods falls, machinists involved in
production may be laid off or forced to work fewer hours. Employment of
machinists involved in plant maintenance, however, often is more stable
because proper maintenance and repair of costly equipment remain
critical to manufacturing operations, even when production levels fall.
Median hourly earnings of machinists were $15.66 in 2002. The middle
50 percent earned between $12.15 and $19.45. The lowest 10 percent
earned less than $9.57, while the top 10 percent earned more than
$23.17. Median hourly earnings in the manufacturing industries employing
the largest number of machinists in 2002 were:
Metalworking machinery manufacturing
$16.75
Other general purpose machinery manufacturing
15.91
Machine shops; turned product; and screw, nut, and bolt
manufacturing
Suggested citation: Bureau of Labor Statistics,
U.S. Department of Labor, Occupational Outlook Handbook,
2004-05 Edition,
Machinists
, on the Internet at http://www.bls.gov/oco/
ocos223.htm
(visited January 27, 2005).
