material selection for springs
TRANSCRIPT
A Spring is a mechanical device that
returns to its original shape, size and
position after it is stretched , squeezed
or twisted.
Properties of alloying elementsManganese (0.25-13%): Increases strength at high temperatures by
eliminating the formation of iron sulfides. Manganese also improves
hardenability, ductility and wear resistance.
Nickel (2-20%): . Nickel increases strength, impact strength and toughness,
while also improving resistance to oxidization and corrosion. It also increases
toughness at low temperatures when added in small amounts.
Chromium (0.5-18%): At over 12 percent content, chromium significantly
improves corrosion resistance. The metal also improves hardenability,
strength, response to heat treatment and wear resistance.
Silicon (0.2-2.0%): This metalloid improves strength, elasticity, acid
resistance and results in larger grain sizes, thereby, leading to greater
magnetic permeability.
Vanadium : Stabilizes ferrite and tin
Purpose of Heat Treatment
Cold DrawnHard
DrawnOil
Tempered
Oil tempering is done to
reduce brittleness
Cold drawing
process
Hard drawing process
Best Material – Carbon Steel
Music Wire (ASTM A228)Highest quality cold drawn, high carbon wire. Good surface finish.
Maximum Operating Temperature : 250 °F
Modulus of Elasticity (E) (psi x 106) : 30.0
Minimum Tensile Strength (psi x 106) : 230 – 399
Density (lb/in3): 0.284
Nominal Chemistry : C 0.70 - 1.00% , Mn 0.20 - 0.60%
Stainless Steel 302/304 (ASTM A313)
Cold drawn general purpose corrosion and heat resistant.
Maximum Operating Temperature : 550 °F
Modulus of Elasticity (E) (psi x 106) : 28.0
Minimum Tensile Strength (psi x 106) : 125 - 325
Density (lb/in3): 0.286
Nominal Chemistry : Cr 17.0 - 19.0% , Ni 8.0 - 10.0%
Medium Quality Material
Hard Drawn MB (ASTM A227)Cold drawn. Average stress applications. Can be readily electroplated.
Maximum Operating Temperature : 250 °F
Modulus of Elasticity (E) (psi x 106) : 30.0
Minimum Tensile Strength (psi x 106) : Class I: 147 – 283 ,Class II: 171 - 324
Density (lb/in3): 0.284
Nominal Chemistry : C 0.45 - 0.85% ,Mn 0.60 - 1.30%
Oil Tempered MB (ASTM A229)Cold drawn and heat treated before fabrication. Slight scale on surface.
General purpose spring wire.
Maximum Operating Temperature : 250 °F
Modulus of Elasticity (E) (psi x 106) : 30.0
Minimum Tensile Strength (psi x 106) : Class I: 165 – 293 , Class II: 191 - 324
Density (lb/in3): 0.284
Nominal Chemistry : C 0.55 - 0.85% , Mn 0.60 - 1.20%
Other Material – Ferrous
Oil tempered silicon Chrome (ASTM A401)Cold drawn and heat treated before fabrication. Used for shock loads and moderately
elevated temperatures.
Maximum Operating Temperature : 475 °F
Modulus of Elasticity (E) (psi x 106) : 30.0
Minimum Tensile Strength (psi x 106) : 235 - 300
Density (lb/in3): 0.284
Nominal Chemistry : C 0.51 - 0.59% , Cr 0.60 - 0.80% ,Si 1.20 - 1.60%
Oil Tempered Chrome Vanadium (ASTM A231)Cold drawn and heat treated before fabrication. Used for shock loads and
moderately elevated temperatures.
Maximum Operating Temperature : 425 °F
Modulus of Elasticity (E) (psi x 106) : 30.0
Minimum Tensile Strength (psi x 106) : 190 - 300
Density (lb/in3): 0.284
Nominal Chemistry : C 0.48 - 0.53% ,Mn 0.70 - 0.90% ,Cr 0.80 - 1.10% , V 0.15 Min %
Other Material – Non Ferrous Phosphor Bronze (ASTM B159)Cold drawn. Good corrosion resistance and electrical conductivity.
Maximum Operating Temperature : 200 °F
Modulus of Elasticity (E) (psi x 106) : 15.0
Minimum Tensile Strength (psi x 106) : 105 - 145
Density (lb/in3): 0.320
Nominal Chemistry : Cu 94.0 - 96.0%, Sn 4.0 - 6.0%
Beryllium Copper (ASTM B197)
Cold drawn. Good corrosion resistance and electrical conductivity. Good physical strength.
Maximum Operating Temperature : 400 °F
Modulus of Elasticity (E) (psi x 106) : 18.5
Minimum Tensile Strength (psi x 106) : 150 - 230
Density (lb/in3): 0.298
Nominal Chemistry : Cu 98.0%, Sn 2.0%
CNC Multi-Axes Wire Bender
Machine
•Computer guided forming
machine provides feed.
•Sensor records angle of each
spring
•Can produce 2000 springs per
hour depending on side
•Can produce all kinds of springs
but on different forming machines
• The diameter ranges from as
thin as hair to as thin as a broom
stick.
Thank You
Reference : Wikipedia
Introduction To Machine Design – VB Bhandari
http://springipedia.com/material-spring-materials.asp
http://www.bettersprings.com/