This high quality high-carbon spring wire is the most common and readily available today. You might say that music wire will give you the biggest bang for your buck. This material is widely used for helical compression, extension and torsion springs in a wide range of applications, especially in the finer wire diameters. Known for its high tensile strength, high elastic limit, music wire can withstand high stresses under repeated loadings, and will continue to perform well under many normal cyclic applications.
Music wire is manufactured by a hard-drawn process, ideally to a “patented” specification. Today, in the North American market, the sizing is specified in decimal inch, available from .005” to .283”. Local distributors stock material manufactured in primarily in Canada, the United States, Korea and Japan.
The common specification standard used in everyday practice is ASTM A 228 (from the American Society for Testing and Materials).
A few interesting design considerations for music wire:
Elastic Limit – Percent of tensile strength: in tension, 65 to 75 percent; in torsion, 45 to 50 percent.
Hardness, Rockwell – 42 to 46 °C.
Electrical Conductivity – Percent of copper, 8 to 12 percent.
Bending Properties – All diameters should be capable of being bent around an arbour equal to the wire diameter without breaking or cracking the surface.
Weight – per cubic inch, 0.284 (0.129 kg); per cubic centermeter 7.85 g.
Referred to as “stress relieving”, “baking” or “stress equalizing” by spring makers, this operation should be done shortly after cold coiling or forming to remove residual coiling or bending stresses and to settle the molecule structure (or the resetting of the memory). At Springs & Things Inc. all springs and wire forms are stressed relieved by default, anywhere from 400 °F (200 °C) to 550 °F (290 °C). Normal tempering time is 30 minutes.
Interestingly, a usually desirable outcome arises from the stress relieving process known as “secondary hardness.” A spring will gain 2 to 3 points of Rockwell C hardness, resulting in an increase in the tensile strength and elastic limit.
|C, Carbon||Mn, Manganese||Si, Silicon||P, Phosphorous||S, Sulfur|
|0.70 – 1.00||0.20 – 0.60||0.10 – 0.30||0.025 max||0.030 max|
Springs & Things Inc. has been our vendor for the past 17 years. They are an integral component of our success. We are thankful to have been introduced to them, and they manufacture many of our products. I always enjoy going to the shop. The team is so accommodating, patient and helpful. I always leave there with a smile on my face.
Robina Bernard, Founder Clik-Clik Systems™ Inc.