Forged Products

The Basic Principles

The two main processes in open die forging are press forging and hammer forging. Both involve the shaping of heated metal parts between a top die attached to a ram and a bottom die attached to a hammer anvil or press bed. Some key differences between the process are listed below.

Size
	Hammer forging is limited by size. Weights of 500 kgs to 650 kgs are commonly seen as the upper limit for this process. Above this size the advantages of press forging take over, this being due to the almost unlimited amount of power that can be generated from hydraulics’.
Material Properties
	Hammer forging involves hitting the material at high velocitiesresulting in finer grain structures and better mechanical properties than achieved though the slower press forging process. However the increased deformation and control achieved though press forging will give the material better through working and consistency of properties.
Tolerances
	Hammer forging can work to nearer net shape with smaller forging allowance, therefore on high cost or difficult to machine alloys there can be significant advantages in the hammer forging process.

Forging produces predictable and uniform products with:
	Refined grain size and flow characteristics through mechanical hot deformation
	Superior metallurgical and mechanical qualities, together with increased directional strength
	A higher degree of structural integrity
	Elimination of internal voids and gas pockets, which can weaken metal parts.
	Superior chemical uniformity by the dispersion of non-metallics and segregated elements in the cast structure

	Shaped Forging Advantages: Directional alignment has been achieved through deliberately orienting the forging process in the direction requiring maximum strength. This also yields higher ductility and greater resistance to impact and fatigue.
	Forged Bar: Unidirectional grain flow has been suddenly curtailed at the changed contour, exposing grain ends. This renders the material more liable to fatigue and possibly sensitive to stress corrosion cracking.

Forging to near net shape not only provides savings in material usage but can also dramatically improve structural integrity through the control of product grain flow.

1. Rough forging a heated billet between flat dies to the maximum diameter dimension.		2. A "Knife" tool marks the starting locations.
3. Drawing down the first step to size.		4. The second step is drawn down to size.
5. Swaging the rough forging for a smoother surface finish and to keep allowance to a minimum.

1. Starting stock cut to size by weight is first rounded, then upset to achieve structural integrity and directional grain flow.		2. Work piece is punched, then pierced to achieve starting "doughnut" shape needed for ring rolling process.
3. Completed preform ready for ring production.		4. A "pin" or mandrel is placed through the preform allowing the ring to be opened out. This process is sometimes called "Becking out".
5. The rings thickness is controlled by forging under a flat die and bed intermittently with the Becking process.

This idler roll then moves under pressure toward a drive roll that continuously rotates to reduce the wall thickness, thereby increasing the diameters (I.D. and O.D.) of the resulting ring. The axial rolls control the height of the ring as it is being rolled. The process continues until the desired size is achieved.

Seamless rings can be produced in configurations ranging from flat, washer-like parts to tall, cylindrical shapes. The simplest, and most commonly used shape is a rectangular cross-section ring, but shaped tooling can be used to produce seamless rolled rings in complex, custom shapes with contours on the inside and/or outside diameters.

1. Completed preform ready for placement on ring mill for rolling.		2. Ring rolling process begins with the idler roll applying pressure to the preform against the drive roll.
3. Ring diameters are increased as the continuous pressure reduces the wall thickness. The axial rolls control the height of the ring as it is being rolled.		4. The process continues until the desired size is achieved.

Rings, Blanks & Bosses

1500mm OD (60 inch max) 2 tonnes max

Shaped Bars & Shafts

530mm OD (20 inch max) 5 tonnes max       Ring Rolling

4500mm OD max 2 tonnes max

Blocks & Slabs

450mm Section size max 530 tonnes max