Industrial engineering is the branch of engineering concerned with the development, improvement, implementation and evaluation of integrated systems of people, money, knowledge, information, equipment, energy, material and process. There are a number of things industrial engineers do in their work to make processes more efficient, to make products more manufacturable and consistent in their quality, and to increase productivity.
Industrial engineering draws upon the principles and methods of engineering analysis and synthesis, as well as mathematical, physical sciences and social sciences together with the principles and methods of engineering analysis and design to specify, predict and evaluate the results to be obtained from such systems. In lean manufacturing systems, industrial engineers work to eliminate wastes of time, money, materials, energy and other resources.
Industrial engineering is also known as operations management, systems engineering, production engineering, manufacturing engineering or manufacturing systems engineering—a distinction that seems to depend on the viewpoint or motives of the user. Recruiters or educational establishments use the names to differentiate themselves from others. In health care, industrial engineers are more commonly known as management engineers, engineering management, or even health systems engineers.
The name "industrial engineer" can be misleading. While the term originally applied to manufacturing, it has grown to encompass services and other industries as well. Similar fields include operations research, systems engineering, ergonomics, process engineering and quality engineering
Whereas most engineering disciplines apply skills to very specific areas, industrial engineering is applied in virtually every industry. Examples of where industrial engineering might be used include: shortening lines (or queueing theory) at a theme park, streamlining an operating room, distributing products worldwide (also referred to as supply chain management), and manufacturing cheaper and more reliable automobiles. Industrial engineers typically use computer simulation, especially discrete event simulation, for system analysis and evaluation.
Ever since its creation with the offering of the world's first industrial engineering program at the Pennsylvania State University in 1906, the jobs and functions performed by IEs have grown vastly. The expertise required by an industrial engineer will include some or all of the following elements:
Value engineering is based on the proposition that in any complex product, 80 percent of the customers need 20 percent of the features. By focusing on product development, one can produce a superior product at a lower cost for the major part of a market. When a customer needs more features, they are sold to them as options. This approach is valuable in complex electromechanical products such as computer printers, in which the engineering is a major product cost.
To reduce a project's engineering and design costs, it is frequently factored into subassemblies that are designed and developed once and reused in many slightly different products. For example, a typical tape-player has a precision injection-molded tape-deck produced, assembled and tested by a small factory, and sold to numerous larger companies as a subassembly. The tooling and design expense for the tape deck is shared over many products that can look quite different. All that the other products need are the necessary mounting holes and electrical interface.
Quality control is a set of measures taken to ensure that defective products or services are not produced, and that the design meets performance requirements. Quality assurance covers all activities from design, development, production, installation, servicing and documentation. This field introduced the rules “fit for purpose” and “do it right the first time.”
It is a truism that "quality is free"—very often, it costs no more to produce a product that always works, every time it comes off the assembly line. While this requires a conscious effort during engineering, it can considerably reduce the cost of waste and rework.
Commercial quality efforts have two foci. The first is to reduce the mechanical precision needed to obtain good performance. The second is to control all manufacturing operations to ensure that every part and assembly stays within a specified tolerance.
Statistical process control in manufacturing usually proceeds by randomly sampling and testing a fraction of the output. Testing every output is generally avoided due to time or cost constraints, or because it may destroy the object being tested (such as lighting matches). The variances of critical tolerances are continuously tracked, and manufacturing processes are corrected before bad parts can be produced.
A valuable process industrial engineers perform on a wholly assembled consumer product is called the "shake and bake." Every so often, a whole product is mounted on a shake table in an environmental oven, and operated under increasing vibration, temperatures and humidity until it fails. This finds many unanticipated weaknesses in a product. Another related technique is to operate samples of products until they fail. Generally the data is used to drive engineering and manufacturing process improvements. Often quite simple changes can dramatically improve product service, such as changing to mold-resistant paint, or adding lock-washed placement to the training for new assembly personnel.
Many organizations use statistical process control to bring the organization to "six sigma" levels of quality. In a six sigma organization every item that creates customer value or dissatisfaction is controlled, such that a standard for failure of fewer than four parts in one million is upheld. Items controlled often include clerical tasks such as order-entry, as well as conventional manufacturing processes.
Quite frequently, manufactured products have unnecessary precision, production operations, or parts. Simple redesign can eliminate these, lowering costs and increasing manufacturability, reliability and profits.
For example, Russian liquid-fuel rocket motors are intentionally designed to permit ugly (though leak-free) welding, to eliminate grinding and finishing operations that do not help the motor function better.
Another example: rather than unnecessarily requiring parts to be made to extremely precise measurements, some Japanese disc brakes have parts toleranced to three millimeters, an easy-to-meet precision. Yet when combined with crude statistical process controls, this assures that less than one in a million parts will fail to fit.
Many vehicle manufacturers have active programs to reduce the numbers and types of fasteners in their product, to reduce inventory, tooling and assembly costs.
Another producibility technique is "near net shape forming." Often, hundreds of low-precision machining or drilling steps can be eliminated through a premium forming process. For example, precision transfer stamping can quickly produce hundreds of high quality parts from generic rolls of steel and aluminum. Alternatively, die casting can produce metal parts from aluminum or sturdy tin alloys, which are often about as strong as mild steels. Plastic injection molding is another powerful forming technique, especially if the special properties of the part are supplemented with inserts of brass or steel.
When a product incorporates a computer, it replaces many parts with software that fits into a single light-weight, low-power memory part or micro-controller. As computers grow faster, digital signal processing software is beginning to replace many analog electronic circuits for audio and sometimes radio frequency processing.
On some printed circuit boards—itself a producibility technique—the electrical conduction are intentionally sized to act as delay lines, resistors and inductors to reduce the parts count. An important recent innovation was the use of "surface mounted" components. At one stroke, this eliminated the need to drill most holes in a printed circuit board, as well as clip off the leads after soldering.
In Japan, it is a standard process to design printed circuit boards of inexpensive phenolic resin and paper, and reduce the number of copper layers to one or two to lower costs without harming specifications.
It is becoming increasingly common to consider producibility in the initial stages of product design, a process referred to as design for manufacturability. It is much cheaper to consider these changes during the initial stages of design rather than redesign products after their initial design is complete.
Industrial engineers study how workers perform their jobs, such as how workers or operators pick up electronic components to be placed in a circuit board or in which order the components are placed on the board. The goal is to reduce the time it takes to perform a certain job and redistribute work so as to require fewer workers for a given task.
Frederick Winslow Taylor and Frank and Lillian Gilbreth did much of the pioneering work in motion economy. Taylor's work sought to study and understand what caused workers in a coal mine to become fatigued, as well as ways to obtain greater productivity from the workers without additional man hours. The Gilbreths devised a system to categorize all movements into subgroups known as therbligs (Gilbreths spelled backwards, almost). Examples of therbligs include hold, position, and search. Their contributions to industrial engineering and motion economy are documented in the children's book Cheaper by the Dozen.
A modern descendant of the therblig system is the set of process chart symbols developed by the American Society of Mechanical Engineers (ASME). The five ASME symbols are for inspection, delay, storage, transport, and operation.
Industrial engineers frequently conduct time studies or work sampling to understand the typical role of a worker. Systems such as Maynard Operation Sequence Technique (MOST) have also been developed to understand the work content of a job.
While industrial engineers still perform time-and-motion studies, many modern industrial engineering projects focus more on "knowledge work" and supervisory control instead of manual labor. Thus, many industrial engineers also have training in human factors or ergonomics and contribute more broadly to the design of work processes.
Although industrial engineering courses had been taught by multiple universities in the late 1800s, the first department of industrial engineering was established in 1908 at Pennsylvania State University.
The first doctorate degree was awarded for industrial engineering in the 1930s by Cornell University.
In the United States, the usual undergraduate degree earned is the Bachelor of Science in Industrial Engineering (BSIE). The typical BSIE curriculum includes introductory chemistry and physics, mathematics through calculus and differential equations and also including probability and statistics, intermediate coursework in mechanical engineering, computer science, and sometimes electrical engineering, and specialized courses such as the following:
Several examples of BSIE curricula in the United States are available online, including those of University of Oklahoma, Bradley University, Pennsylvania State University, Georgia Institute of Technology, Arizona State University, Hofstra University, Iowa State University, Purdue University, University of Illinois at Urbana-Champaign, and University of Wisconsin at Milwaukee.
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