High Carbon Wire Springs
Custom springs manufactured with high-carbon steel are one of the most commonly used spring materials for various applications. High carbon steel wire in an economical option for high volume orders and applications requiring standard accuracy and deflection.
Hard Drawn Spring Wire
Hard Drawn spring materials are popular option for commercial mechanical applications. It is a medium carbon, cold drawn wire that performs well in applications that require average stress loads. Most of the time when prints specify “hard drawn,” they mean bright hard drawn (has a phos coating-same as music wire), specs to ASTM A-227. Hard Drawn can be specified as Class 1 or 2, Class 1 is the type typically stocked. The tensile range of hard drawn wire for the same size of Music wire will be lower. Hard Drawn wire can also be purchased in the pre-galvanized condition. Hard Drawn can have most post finish process applied but will need a bake operation for any electrolytic process to relieve for hydrogen embrittlement.
Music Spring Wire
Also referred to as Piano wire, music wire is a tough material with a high tensile strength that can withstand higher stress under repeated loading than other materials. It also has excellent fatigue life and can be plated after forming. This is a fairly high-grade, high-carbon steel wire made to specification ASTM A-228. It is a “cleaner” steel with a surface that has fewer draw marks than hard drawn and exhibits a better fatigue life. Today, music wire is made by either direct drawing from rod or lead patenting. As a guide, most stocked music wire larger than 0.0625″ is more likely to have been direct drawn; whereas wire smaller than 0.0625″ will have been made from lead-patented rod or wire. Wire made by the patenting method has a higher cost. Music wire can also be purchased in the pre-galvanized condition. Music wire can have most post finish process applied but will need a bake operation for any electrolytic process to relieve for hydrogen embrittlement.
Stainless Steel Spring Wire
A high-chromium steel, often including nickel, which is resistant to corrosive and oxidizing attack. The most well-known type is 18/8, an austenitic steel containing about 8% nickel. The carbon is typically kept low. This is often referred to as “Type 302” or “Type 304.” The main difference between the two grades is that Type 302 has a maximum permitted carbon content of 0.12%, whereas Type 304 has a maximum permitted carbon content of 0.08%. As a rule, 304 will almost always meet the 302 analyses but not the other way around. Stainless wire that is spring tempered will be slightly magnetic because of the drawing process. Type 316 will be less magnetic and more corrosion resistant than type 302-304 but is significantly more expensive. Stainless wire is approximately 17% weaker than Music or Hard Drawn wire, so for those stainless applications needing a higher tensile or to reduce stress levels 17-7 will have tensile levels like music wire. Corrosion resistance for 17-7 will be the same as 302/304.