1. AHMEDABAD INSTITUTE OF TECHNOLOGY
Prepared By
– Nirmal Sinroja
– Smit Patel
– Kirtee Sohalia
– Aditya Soni
– Rutul Soni
Guided By
P D Panchal & J R Mewada

2. Design of
Helical spring

3. Springs Springs Characterized By:
Ability to deform significantly without failure
Ability to store/release PE over large deflections
Provides an elastic force for useful purpose

4. Springs How used in mechanical design? Shock/Vibration protection
Store/Release PE
Offer resisting force or reaction force for mechanism
Example:
Valve spring pushes rocker arm so lifter follows cam
VCR lid – torsion springs keeps door closed

5. Function of Helical spring
Helical spring is a spiral wound wire with
a constant coil diameter and uniform pitch.
Function of Helical spring
Used to store energy and subsequently release it
To absorb shock
To maintain a force between contacting surfaces

6. Design consideration of helical spring

8. Nomenclature of Helical spring
C = Spring Index D/d d = wire diameter (m) D = Spring diameter (m) Di = Spring inside diameter (m) Dil = Spring inside diameter (loaded ) (m) E = Young's Modulus (N/m2) F = Axial Force (N) G = Modulus of Rigidity (N/m2) K W = Wahl Factor = [(4C-1)/(4C+5)}]+ (0,615/C) L 0 = Free Length (m) L s = Solid Length (m) n t = Total number of coils n = Number of active coils p = pitch (m) y = distance from neutral axis to outer fibre of wire (m) τ = shear stress (N/m2) τ max = Max shear stress (N/m2) θ = Deflection (radians)

9. Spring material High carbon steel 4. Copper based alloy
Music Wire (ASTM A228)
Hard Drawn (ASTM A227)
High Tensile Hard Drawn (ASTM A679)
Oil Tempered (ASTM A229)
Carbon Valve (ASTM A230)
Alloy spring steel
Chrome Vanadium (ASTM A231)
Chrome Silicon (ASTM A401)
Stainless steel
AISI 302/304 - ASTM A313
AISI ASTM A313
17-7 PH - ASTM A313(631)
4. Copper based alloy
Phosphor Bronze (Grade A) - ASTM B159
Beryllium Copper - ASTM B197
Monel 400 (AMS 7233)
Monel K500 (QQ-N-286
Nickel based alloy
A286 Alloy
Inconel 600 (QQ-W-390)
Inconel 718
Inconel X-750 (AMS 5698, 5699)

10. Effect of End treatment

11. The module calculates the following design parameters:
1. Outer Diameter (Do)
5. Maximum load
2. Spring Index (C)
6. Corrected maximum stress
index range is 4 to 12
3. Slenderness ratio
7. Uncorrect maximum stress
4. Spring rate (k)
8. Wahl correction factor

12. 12. Shear stress
9. Maximum deflection
10. Spring mass
13. uncorrected Shear stress
11. Wire length
14. Natural frequency

13. Stability of spring (buckling)
CHECKING
Stability of spring (buckling)
2. Fatigue loading

14. Spring testing machine

15. Thank You