Ductile Iron Gears
Ductile
iron is basically a cast iron in which the flakes of graphite are changed by
the process of chemical reaction. They are transformed into nodules or
spheres. In recent times, gear makers are increasingly opting for Ductile
Iron Gears as a cost saving alternative to steel gears.
Comparison with Steel Gears
Those vouching for Ductile iron Gears stresses the distinct advantages of
them over cast steel gears. These are the following:
- Ductile iron is similar in strength to a cast steel.
- Ductile iron is easier to pour.
- High hardness is easily obtainable.
- Supposedly better sliding wear against the steel pinions.
- After machining Ductile iron gives better dimensional stability.
- Weight reduction by at least 10%.
- Reduced gear noise.
- Increase in machine shop productivity.
Comparison of energy requirements : ADI vis-a-vis Forged steel
gears
|
Energy consumption (kWh/ Tonne) |
| Operation |
Austempered Ductile Iron |
Forged steel Gears |
| Production of blank Annealing |
2500 |
4,500
500 |
| Austempering |
600 |
--- |
| Case-hardening |
--- |
800-1,200 |
| Total |
3,100 |
5,800-6,200 |
Ductile Iron Gears in Mining
Applications 
ADI (Austempered Ductile Iron) gear segments is an integral feature of the
mining industry. The gear segments are applied in rail tipping assemblies
for emptying entire rail cars filled with ore.
The alloys for the gears has:
Tensile strength: 150,000 PSI
Yield strength: 100,000 PSI
Buyer's Consideration in Ductile iron
Gears
As an informed buyer the following things needs to be checked for zeroing
on to the best ductile iron gears:
- Tensile strength
- Chemical analysis
- Material hardness
- Required AGMA levels
- Inspection of - magnetic particle - dimensions
- Ultrasonic inspection
