Introduction to Industrial Engineering

By Jane M. Fraser

Chapter 6

Design or improve a production system

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6.1 How many of what type of physical assets does the organization need?

Depending on the type of steel the company will make in a plant, a steel company chooses what type of equipment it needs: a furnace, ladles, molds, gates and other devices to control the flow of the molten steel, and so forth. The American Steel and Iron Institute has a good explanation of how steel is made and the types of equipment used.

Depending on the type of care the hospital will provide at a particular location, the hospital chooses what type of equipment it needs: beds, stretchers, and other equipment for patients; diagnostic equipment such as ultrasound machines, X-ray machines, and blood testing equipment; computer technology to store data on patients; and so forth.

Every industry has suppliers of equipment who are eager to help you, the IE, decide to select their equipment. For example, has a directory of suppliers and allows a user to request bids from various suppliers. Hospital Technology helps hospital adminstrators find "medical equipment, hospital supplies and services. "

In selecting what equipment to purchase use, the organization should consider the following types of factors:

The design of a product or service leads to requirements for certain types of equipment. One of the important choices made during design is the tolerance on a dimension. The required dimension on a part is specified by the design engineer, who also specifies the tolerance required on that dimension. For example, the design engineer might specify that the length of a rod should be 10.215 cm plus or minus .001 cm. The production process must reliably produce rods with lengths between 10.215-.001 = 10.214 cm and 10.215+.001 = 10.216 cm. Generally, a tighter tolerance requires a more expensive machine. The article "Think You Can’t Afford New CNC Multi Technology?" from Production Machining describes why a manufacturing company purchased sophisticated CNC (Computer Numerical Control) machines in order to be able to consistently meet the tight tolerances being specified by their customers.

Because achieving tight tolerances is expensive, design engineers should be very careful that their specified tolerances are truly justified and the IE should look at the design and perhaps question some of the design decisions made by the design engineer. The best situation is when the IE is involved in the design, so the design engineer designs for manufacturability.

The volume of production will affect the equipment purchased. For example, office equipment (such as copiers, faxes, and shredders) have different capacities. The first question an office supplier asks if you want to purchase a copier is how many copies the office makes per month. Similarly, a manufacturing environment running three shifts, six days a week, requires different machines than a shop that occasionally uses a particular machine.

Selecting a good supplier for equipment can be crucial and cannot be based only on the initial cost. The article “Guidelines for New Users .. Selecting the ‘Right’ Supplier,” from Robotics Online gives advice about how to pick a company to supply a robot. It suggests that you consider: company size, geographic presence, markets served, applications addressed, financial performance, support, staffing, documentation, spare parts, service, and warranties.

For some parts that go into a product, the IE may need to consider whether to make the part in house or buy the part from a supplier who specializes in that part. For example, most manufacturers purchase fasteners (bolts, screws, etc.) rather than making them in house because fasteners can be made more cheaply with higher quality by a company that specializes in making fasteners.

In order to make decisions about the purchase of capital assets for production, the IE will have to know something about the industry. For example if you go to work for a steel mill, you will need to learn about the equipment used to make steel. If you go to work for a company that makes integrated circuits, you will need to learn about those manufacturing processes and the equipment used. We can't possibly teach you all the different types of manufacturing processes used in different industries; it would take too long, and you would end up using only a small fraction of what you learned. All IE programs select what they think are the most widely used and most important processes.

In a manufacturing processes class in an IE program, you will learn about the following types of materials:

You will learn about the following types of manufacturing processes.

Source Authority has brief explanations of these and other manufacturing processes. To give you some idea of the mechanical processes involved, read: