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Often spring designs are more expensive and difficult to manufacture due to lack of space. Each type of spring presents its own challenges, however, adequate space for coils and spring diameters can simplify design and save cost when placed into production.
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Figure 1
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R = Rate (Spring Constant)
G = Modulus of Rigidity
d = Wire Diameter
na = Active Coils
D = Mean Coil Diameter
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Figure 2
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D = Mean Coil Diameter
d = Wire Diameter
S = Stress
P= Load
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Review of the basic spring design equations for spring rate (Fig 1), along with the stress equations (Fig 2, uncorrected), indicates the variables available to change force and the ramifications of spring stresses. Most problems arise with stress and cycle life. Often the best solution is to increase the wire diameter of the spring or simply add coils. When proper space allowances are not made, prototype and production cost rise. Set removal and shot peen operations are added to improve stresses. Additionally, shaped wire may be required to satisfy both strength and space constrains, which also adds additional cost and design time to satisfy the design criteria. It is always best to consult with your spring manufacturer in the early phase of the design of new product in order to determine the best design considering the allowable space. Doing so will save engineering time and possible re-engineering of the product.
-The 18th China(Guangzhou)Int’l Springs
Industry Exhibition
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