Peter Ulintz
PMA Technical Consultant

Nomenclature—Are We Talking About the Same Thing?

Merriam-Webster defines “nomenclature” as the devising or choosing of names for things, especially in a science or other discipline. These are the words or terms that we use to communicate technical ideas or principles. But are we all talking about the same thing?

Accepted nomenclature often tends to be regional. For example, those living in the United States view a bonnet as a variety of headgear sometimes worn by women. In the United Kingdom a bonnetcould be interpreted as a car hood.

Another example: a pneumatic pressure system beneath the bolster plate in a stamping press. In North America we refer to this as an air cushion; in the U.K. it’s a marquette.

Some terms are outright misused, such as the word “mil.” A press-shop may say, “The sheet is 1 mil thick.” Do they really mean 1 mil, or do they mean 1 mm? Contrary to common belief, the two are not the same: 1 mil is 0.001 in. while 1 mm is 0.03937 in.

The terms “punch” and “die” often are misinterpreted, too, primarily because they contain double meanings. For example, we often refer to a complete stamping tool as a “die,” and the individual that built it a “diemaker.” The die comprises two main sections: the upper die, often referred to as the punch, and the lower die, often referred to as the die. This is pretty clear until you consider that “punch” also may refer to one or more male forming or piercing components mounted to either the upper punch shoe or the lower die shoe. When the die is mounted to the punch and the punch mounted to the die, things get confusing.

Another source of confusion relates to hole-making terminology. Are they punched or pierced? We can differentiate between punching and piercing by emphasizing the fact that punching produces a slug, piercing does not. Piercing operations often (but not always) are defined as “forming a hole in sheetmetal with a pointed punch with no material fallout” (see the accompanying figure).

Nomenclature defined through one particular industry’s national or international standards organizations may be misused by other industries. For example, steel users/ metalformers often misuse the nomenclature of the steel-producing industry. Steelmakers have standards that clearly define the difference between sheet and strip products. The difference lies primarily with how the materials are produced, and their quality level.

Steel mills ship sheet and strip steel products as coils. Users, on the other hand, tend to define sheet and strip by their shape. Sheet steel is flat and wide (4 ft. wide by 8 ft. long, for example). Strip is flat and narrow (2 in. wide by 8 ft. long, for example). When a user receives material in coil form, it considers the material coil—not sheet nor strip. This completely contradicts steel-industry standard definitions.

Inconsistent use of steel nomenclature can negatively impact press-shop problem-solving, part quality and operational profitability. For example, using 24-in.-wide cold-rolled strip steel, which exhibits consistent properties, thickness control and surface finish, compared to sheet products, may be the ideal solution to an existing problem in the press shop. Unfortunately, this option may never be considered if the press shop believes that strip steel does not come in coil form.

Another misuse of steel terms relates to the new advanced high-strength steels (AHSS). We often hear users refer to these materials as advanced high-strength low-alloy steel. AHSS grades, however, contain a lot of alloying that helps them attain their ultra-high-strength levels. In fact, some AHSS materials have yields strengths exceeding 100 ksi, while some high-strength low-alloy steels also offer 100-ksi yield strength. Therefore, it’s critical to learn and use the correct nomenclature when ordering these materials.

Why all of the emphasis on nomenclature? If we cannot accurately communicate amongst ourselves using a common spoken language, what kind of problems will you have as a global supplier that must communicate accurately with customers around the world, translating between multiple languages?

Make a point to know, understand and use the correct nomenclature in your industry. We all need to be talking about the same thing. MF

Technologies: Tooling

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