Types of Forging Processes
Forging is classified two ways at once: by how the metal is contained (open die or closed die), and by the temperature it is worked at (hot, warm or cold). Every forging process is a combination of those two axes.
Forging types are classified three ways: by die (closed die, open die, ring rolling), by temperature (hot above 1,100°C, warm at 750–950°C, cold at room temperature), and by equipment (drop hammer, press, upset). Hot closed die forging is the most widely used combination.
- By die
- Closed die, open die, ring rolling
- By temperature
- Hot, warm, cold
- By equipment
- Drop (hammer), press, upset
- Most common
- Hot closed die forging
- Tightest tolerance
- Cold forging, ±0.1 mm
- Largest parts
- Open die, up to 500 kg here
Types of Forging Processes at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Three classification axes: die, temperature, equipment
- Hot closed die forging is the most common route
- Cold forging holds ±0.1 mm, hot forging ±0.5 mm class
- Open die needs no tooling, so single pieces are viable
- Ring rolling covers 100–1,200 mm outside diameter
Classified by Die Type
Closed die forging traps metal in a shaped cavity, producing repeatable near-net parts with complex geometry. Open die forging works metal between flat or simple tools with no cavity, suiting large simple shapes and one-off pieces. Ring rolling is a specialised open die variant producing seamless rings.
- Closed die: shaped cavity, repeatable
- Open die: free forming, no tooling cost
- Ring rolling: seamless circumferential grain
- Chosen by geometry and quantity
Classified by Temperature
Hot forging above 1,100°C gives maximum formability for complex shapes. Warm forging at 750–950°C trades some formability for better accuracy. Cold forging at room temperature holds ±0.1 mm but only on simpler geometry in ductile grades.
Classified by Equipment
Drop forging uses hammer impact, flexible and quick to change over. Press forging applies continuous squeeze, better on thick sections and more consistent. Upset forging compresses a bar axially to form heads and collars without removing material.
People also ask
What is the difference between open die and closed die forging?
Closed die forging uses a shaped cavity that produces repeatable near-net parts but requires a die costing lakhs. Open die forging shapes metal between simple tools with no dedicated tooling, so single pieces are viable but tolerances are looser.
Which forging process is used for crankshafts?
Hot closed die forging, usually on a press so that deformation reaches the core of the heavy web sections and journal fillets receive proper grain flow.
What is ring rolling used for?
Producing seamless rings for bearing races, gear rims, slew rings and flanges, where grain must run continuously around the circumference to resist hoop stress.
Topics covered on this page
- closed die forging
- open die forging
- ring rolling
- hot forging
- cold forging
- warm forging
- drop forging
- press forging
- upset forging
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
What are the main types of forging?
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Closed die, open die and ring rolling by die type; hot, warm and cold by temperature; drop, press and upset by equipment.
Which type of forging is most common?
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Hot closed die forging, because it handles complex geometry at moderate cost in production quantities.
Which forging type gives the best tolerances?
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Cold forging, around ±0.1 mm, though it is limited to simpler shapes in ductile grades.
Which type suits a single replacement part?
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Open die forging, since it needs no dedicated tooling and a single piece is economically viable.