Explore the Materials Used for Spring Manufacturing
The first step in the manufacture of coil springs is the selection of the appropriate metal from which to fabricate the springs. Critical to the selection process is the tensile strength of the metal such that it conforms to the demands of the application. The majority of springs are made from steel alloys due to their abundance and cost. Copper and nickel alloys are also used for specific applications.
The type of metal chosen to produce a metal spring has to be able to hold and release the necessary mechanical energy for a long period of time without failure. The main properties of well made coil springs is their ability to supply force between contacting surfaces and being able to absorb shock and stress.
I. High Carbon Steel
High carbon steel is the most popular type of steel for the manufacture of coil springs. It is strong, durable, and economical and is available in 1045 and 1095 alloys. High carbon steel has a 1% carbon content with a manganese content of 0.9% and a very fine pearlite layer structure that makes the steel very hard, brittle, and less ductile.
II. Music Wire
Music wire, also known as piano wire is considered the toughest of the coil spring wires. It is a high carbon spring steel that is uniform, has high tensile strength, and has the ability to withstand the stress produced by multiple loading. Music wire has exceptional temperature resistance and is often used in foundries and refractories with extremely hot internal temperatures.
III. Chromium Vanadium Steel
Chromium vanadium steel has exceptional strength with flexibility. When used to produce coil springs, it has a medium carbon content that gives it toughness and wear resistance. The addition of vanadium to steel makes it easier to shape without the fear of it breaking. In processing chromium vanadium steel, it is heat treated to increase its resistance to wear and fatigue. It is designed to be used in high stress environments where there are moderately elevated temperatures.
IV. Chromium Silicon Steel
Chromium silicon steel is known for its high hardness and ability to withstand high stress. Its hardness and heat resistance make it ideal for use at temperatures exceeding 275° F. Chromium silicon steel was developed as coil springs for anti-aircraft weapons that have high shock loads.
V. Stainless Steel
When speaking of stainless steel, it is important to specify the grade of stainless steel since each grade has properties and characteristics designed to meet the needs of select applications.
1. Stainless Steel 302 is the most common stainless steel wire used to manufacture coil springs. It is especially useful if the coil spring is going to be exposed to moisture or a corrosive environment. Stainless steel 302 can resist the effects of high temperatures up to 550° F or 228° C. It is the softest and most flexible of the various stainless steel with high tensile strength.
2. Stainless Steel 316 is one of the cleanest stainless steels and has all of the other properties of resistance to moisture and can resist the effects of high temperatures. Although it has positive qualities, it is the weakest of the three types of wire used to produce coil springs.
3. Stainless Steel 17-7 is resistant to the effects of moisture and corrosion but is stronger and harder than 302 and 316. The hardness of stainless steel 17-7 makes it possible to produce coil springs with greater force and stiffness. Stainless steel 17-7 is able to resist the effects of temperatures up to 650° F or 343° C.
VI. Silicon Manganese Steel
The silicon in silicon manganese steel increases the steel's hardness, controls its decomposition in tempering, and strengthens its ferrite. Manganese also adds to the hardness of the steel and reduces its decarburization. Coil springs made using silicon manganese steel are hot-formed at 900° C to produce a coil spring with a hardness of 225 BHN. Silicon manganese coil springs are used for torsion bars, railway cars, leaf springs for automobiles, and stabilizers.
VII. Copper Based Spring Alloys
The popular use of copper based spring alloys is due to their electrical properties and high corrosion resistance. The additional and attractive properties of copper based alloys make them more expensive. They are frequently used in electrical components and subzero temperatures.
1. Beryllium Copper has electrical conductivity, corrosion resistance, and high mechanical strength with higher tensile strength compared to other copper alloys and good fatigue strength. It is able to retain its ductility even when placed in cryogenic conditions. The non-magnetic properties of beryllium copper make it an ideal choice for use in the medical field in MRI machines and directional drilling equipment for industrial use.
2. Phosphorus Bronze contains copper, tin, and phosphorus and has greater corrosion resistance and strength than other copper alloys due to the addition of tin. The phosphorus content increases its wear resistance and the stiffness of coil springs made from it. Phosphorus bronze coil springs have excellent strength, good fatigue resistance, and good machinability. They are used for marine fuel pumps, oil rigs, and oil pipeline valves.
VIII. Nickel Based Spring Alloys
The use of nickel based alloys for the production of coil springs is due to nickel's high corrosion resistance and its ability to withstand extremely high temperatures and temperatures below zero. Since nickel based alloys are non-magnetic, they can be used in gyroscopes, chronoscopes, and indicator instruments. They are resistant to the effects of electrical currents and are very poor electrical conductors. Nickel based spring alloys have a Rockwell Hardness of C35 up to C48.
Described below are a few common nickel based spring alloys.
1. Inconel X750 is a hardened nickel chromium alloy with high strength at temperatures up to 1300° F or 740° C and oxidation resistance up to 1800° F or 982° C and resistance to relaxation.
2. Inconel 600 is a nickel chromium iron alloy with corrosion and oxidation resistance, excellent strength in high temperatures, and resistance to chloride stress cracking because of its high nickel content. Additionally, it is resistant to attacks by inorganic and organic chemicals and performs well at temperatures below –300° F. Spring tempered Inconel 600 is used in applications that require a tensile strength of 220 Ksi. Coil springs produced using Inconel 600 are cold worked.
3. Inconel 625 contains nickel, chromium, molybdenum, and niobium, which provide it with excellent corrosion and oxidation resistance and high strength at high temperatures. The high strength of Inconel 625 is due to its molybdenum and niobium content. Additionally, as with Inconel 600, Inconel 625 is resistant to chlorine stress corrosion cracking and pitting. This property makes it suitable for use in ocean and seawater applications.
4. Inconel 718 is age hardened nickel, chromium, niobium, and molybdenum with excellent corrosion resistant properties. It is a high strength alloy for use in applications with extremes of high and low temperatures.
5. Inconel 718 is ideal for the manufacture of springs due to its exceptional fatigue, creep, and rupture strength. The many positive characteristics of Inconel 718 make it the perfect material for coil springs used in a wide variety of industrial projects and operations.
The metals that are listed above are a few of the types of metals and materials used to produce coil springs. Every day, researchers and engineers are finding other metals, such as aluminum, to be used as coil spring materials.
The content above is excerpted from IQSDirectory.com.
