- Top die can be orbited by a few degrees (a°) about the vertical axis, while the lower die is moved upwards during the forging operation.
- Only a small area of contact, reduces forging loads to only 10% of that of conventional forging at the end of the stroke.
- Best used for components with large-diameter flanges.
- Purpose-built machines are mainly intended for warm forging applications at 0.25–0.6Tm.
- Diameters up to 150 mm can be produced.
- Precise volume, preformed slugs are induction heated and automatically fed to the orbital forging press.
- The blank is progressively formed by an upper conical die which is inclined to and rotated about the machine axis. A lower die, capable of vertical movement only, presses the workpiece against the upper wobbling die. Therefore at any instant the tool-workpiece contact area is small and the forging loads are reduced to only 10–5% of that which is normally required. Capital cost is lower than that required for a much larger conventional forging press.
- Forging output rate can be 375–600 parts h-1.
- Orbital speed of upper die is 1000 oscillations min-1. Press tonnage 200 tonnes.
- Ejection of the forging from the die is automatic and an air blast blows it clear of the die area.
- There is minimal flash formation.
- Process has been used for cold compaction of powder preforms and powder forging applications.
- All forgeable materials can be orbital forged.
- Materials include all carbon and low-alloy steels, stainless steels, aluminium alloys and brasses.
- Powder compacts can be orbitally forged to increase their densities to near theoretical. This is a type of powder forging.
- Process is used to produce components with large-diameter flanges up to 150 mm dia.
- Components include bevel gears, claw clutch parts, wheel discs with hubs, bearing rings, rings of various contours and bearing end-covers. An example is shown below.
- Minimum practical forging thicknesses:
conventional 5 mm
orbital 2.5 mm
- Thickness tolerances on warm forging of steel at 700–800˚C are ±0.15 mm.
- Reduced oxide scale formation compared with hot forging applications.
- Orbital forging should produce 25% material savings and 50% reduced energy costs.
This article is a part of Manupedia, a collection of information about some of the processes used to convert materials into useful objects.