Forged Shafts
Shafts carry torque and bending simultaneously, and every step change in diameter is a stress concentration. Forging the steps rather than turning them from oversized bar keeps grain continuous through each shoulder — precisely where a turned shaft would fail.
- Length Range
- 150 mm – 2,000 mm
- Diameter Range
- 20 mm – 250 mm
- Materials
- EN19, EN24, 42CrMo4, SS 410
- Ground Finish
- Ra 0.4 µm
- Diameter Tolerance
- ±0.01 mm ground
- Features
- Splines, keyways, threads, cross-holes
Forged Shafts at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Length Range: 150 mm – 2,000 mm
- Diameter Range: 20 mm – 250 mm
- Materials: EN19, EN24, 42CrMo4, SS 410
- Ground Finish: Ra 0.4 µm
- Diameter Tolerance: ±0.01 mm ground
- Features: Splines, keyways, threads, cross-holes
Stepped Geometry Without Cutting Grain
On a turned shaft, every shoulder cuts across longitudinal fibres. A forged stepped shaft flows the fibre around each shoulder, and generous forged fillets further reduce the stress concentration factor at the transition.
- Forged steps and shoulders
- Continuous fibre through transitions
- Generous fillet radii
- Straightened after heat treatment
Splines, Keyways and Threads
Involute and parallel splines, keyways, threads and cross-drillings are completed on our CNC turning and VMC cells, with live tooling keeping features in one setup and preserving concentricity.
Straightness and Finish
After quench and temper, shafts are straightened and finish ground to the required runout and surface finish. Bearing seats routinely reach Ra 0.4 µm with diameter tolerance of ±0.01 mm.
Shaft Capability and Finishing Options
Shafts carry torque and bending at the same time, and every change of diameter is a stress concentration. Forging the steps rather than turning them from oversized bar keeps grain continuous through each shoulder — precisely where a turned shaft would begin to crack.
| Parameter | Range |
|---|---|
| Length | 150 mm – 2,000 mm |
| Diameter | 20 mm – 250 mm |
| Materials | EN19, EN24, 42CrMo4, SS 410 |
| Ground diameter tolerance | ±0.01 mm |
| Ground surface finish | Ra 0.4 µm |
| Features | Splines, keyways, threads, cross-holes |
Designing Shaft Shoulders for Fatigue
Most shaft failures start at a feature rather than in a plain section, and the fillet radius at a shoulder is the single most influential detail. A sharp radius can multiply local stress several times over; a generous one, combined with forged grain flowing around the step, dramatically improves fatigue life. Keyways deserve the same attention, since their corners are stress raisers that shaft sizing must account for.
- Generous fillet radii at every shoulder
- Forged steps rather than steps turned from bar
- Keyway corner radii specified, not left to the machinist
- Straightened after heat treatment, then finish ground
Choosing a Shaft Grade by Diameter
Grade selection on shafts is really a hardenability decision. Below roughly 60 mm and at moderate load, EN8 heat treats well and machines freely. Above that, where uniform properties through the core are needed, EN19 is the safer choice. Very large or shock-loaded shafts move to EN24, and shafts needing corrosion resistance with hardness use SS 410.
People also ask
What is the longest shaft you can forge and grind?
Up to 2,000 mm forged, with grinding to ±0.01 mm and Ra 0.4 µm on bearing seats.
Why forge a stepped shaft rather than turn it from bar?
Turning cuts longitudinal grain at every shoulder — the highest stress location. Forging flows grain around each step, substantially improving fatigue life.
Topics covered on this page
- forged shaft manufacturer India
- stepped shaft forging supplier
- splined shaft manufacturer Rajkot
- transmission shaft forging India
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
What is the longest shaft you can forge?
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Up to 2,000 mm on the open die line, with machining and grinding to match.
Do you grind bearing seats?
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Yes, cylindrical grinding to ±0.01 mm and Ra 0.4 µm where the drawing requires it.
Can you cut splines and keyways?
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Yes, both are produced in-house and gauge verified.
Which grade suits high-torque duty?
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42CrMo4 or EN24 quenched and tempered, typically 280–320 BHN core hardness.