Wire Gauge and Other Terms Used In Spring-Making
There is a large variety of wire terms used, like wire gauge, in the spring making and wire forming industry. These terms vary in usage depending on what part of the world you are in. They also vary in usage depending on what industry the spring maker is a supplier to.
For example, suppliers to the furniture industry in North America tend to use gauge size when talking about the wire diameter. In other industries they may simply refer to the diameter of the wire in inches or millimeters when describing the wire size. Here is a chart that shows wire gauge, the different types of wire gauge, and decimal equivalents in inches - Wire Gages and Decimal Equivalents Let's look at some other terms, besides wire gauge, used in relation to spring wire: Tensile Strength: The maximum tensile stress that the material is capable of sustaining. It is calculated from the maximum load during a tension test carried to material rupture and the original cross section area of the specimen. (ASTM A370, ASTM E8) Size Tolerance: Allowed maximum deviation from the nominal diameter. Usually expressed as both plus and minus and in the same units with the same precision as the nominal diameter. (ASTM E29) Roundness Tolerance: The allowed maximum range in size readings at any given point in the wire. The roundness tolerance is usually specified as one half the size tolerance. Wrap Test: A wire sample is coiled in a closely spaced helix around a mandrel of specified diameter. After wrapping the specimen is examined for cracks. The sample is considered a failure if any cracks occur in the wire after the first complete turn. (ASTM A370 Annex A4.7) Coiling Test: A test used to determine if imperfections are present to the extent that they may cause cracking or splitting during spring coiling and spring extension. A coil of specified length is closed wound on an arbor of a specified diameter. The closed coil is then stretched to a specified permanent increase in length and examined for uniformity of pitch with no splits or fractures. (ASTM A370 Annex A4.8) Bend Test: A test piece is bent through a specified angle around a specified mandrel. When complete fracture does not occur, the convex side of the sample is examined for cracks. (ASTM E290) Torsion Test: A straight length of wire is twisted in a fixture until fracture occurs. The fracture surface should be perpendicular to the axis of the wire and free from cracks or other serious flaws. (ASTM E558) Decarburization: The loss of carbon from a ferrous alloy as a result of heating in a medium that reacts with carbon. (ASTM E1077) Cast & Helix: Cast is the diameter of the circle formed by a length of wire thrown loosely on the floor or a similar flat surface large enough in area to support the sample. Diameter of cast to be agreed upon by purchaser and seller. Helix or pitch is the amount of separation between two overlapping cut ends of a wire loop when held vertically by a finger or a similar support. Distance of separation to be agreed upon between the purchaser and seller. Reduction of Area: The difference between the original cross sectional area of a tension test specimen and the area of its smallest cross section. The reduction of area is usually expressed as a percentage of the original cross-sectional area of the specimen. (ASTM A370, ASTM E8) Standards of SpecificationTerms like wire gauge and other terms are based on the different specification standards used in this industry. For example, our definitions above were based on ASTM standards. Here is a brief summary of the standards used world wide- UNS: Unified Numbering System is a joint publication of the American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE). A UNS designation is not, in itself, a specification, since it establishes no requirements for form, condition, property or quality. It is a unified identifier of a metal or alloy for which controlling limits have been established in specifications published elsewhere. ASTM: ASTM standards are issued by the American Society for Testing and Materials
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AISI: Stands for American Iron and Steel Institute. AISI and SAE developed a system of designation for standard steels. For a description see SAE J403. AMS: SAE/Aerospace Materials Standards are issued by the Society of Automotive Engineers. SAE: SAE standards are issued by the Society Of Automotive Engineers and may be purchased at-
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Federal, MIL. Sp.: Federal and Military specifications are issued by the United States Government and are available from-
Standardization Documents Order Desk
JIS: JIS standards are issued by the Japanese Standards Association DIN: DIN standards are issued by the Deutsches Institut for Normunge e.V. English translations can be obtained from -
Global Engineering Departments
BS: British standards are issued by the British Standards Institute You can go to this page to see how these standards are used in classification of the different wire types- Spring Steel and Alloy Wire Types. Stay tuned for updated information related to wire gauge and the other terms used related to spring wire. Our team and visitors to spring-makers-resource.net will be contributing. Got some info you want to share? Send it our way -
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