Forging defects:

Though forging process give generally prior quality product compared
other manufacturing processes. There are some defects that are lightly
to come a proper care is not taken in forging process design.

A brief description of such defects and their remedial method is given below.

(A): Unfilled Section:

In this some section of the die cavity are not completely filled by the flowing metal. The causes of this defects are improper design of
the forging die or using forging techniques.

(B): Cold Shut:

This appears as a small cracks at the corners of the forging. This is caused manly by the improper design of die. Where in the corner and
the fillet radii are small as a result of which metal does not flow
properly into the corner and the ends up as a cold shut.

(C): Scale Pits:

This is seen as irregular deputations on the surface of the forging. This is primarily caused because of improper cleaning of the
stock used for forging. The oxide and scale gets embedded into the
finish forging surface. When the forging is cleaned by pickling, these
are seen as deputations on the forging surface.

(D): Die Shift:

This is caused by the miss alignment of the die halve, making the two halve of the forging to be improper shape.

(E): Flakes:

These are basically internal ruptures caused by the improper cooling of the large forging. Rapid cooling causes the exterior to cool
quickly causing internal fractures. This can be remedied by following
proper cooling practices.

(F): Improper Grain Flow:

This is caused by the improper design of the die, which makes the flow of the metal not flowing the final interred direction.

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Some More Defects such as

1.OverLap - Material is folded in the die.It is due to poor die design,poor roll design not cleaning of dies before forging.

2. Under filling - Other reasons are Less Raw material,Poor heating,Poor draft angle.

3. Crack - Due to improper core heating of the material.

May I know how frequent the following inspection should be carried out (by forging supplier) to assure the quality of the forged parts?

1.  Grain flow

2. Yield Strength.

3.  NDT (which type of NDT should be used?)

It is reasonable to perform 100% NDT check on forged parts?

Beside the dimension & visual inspection, what others inspection needed on forged parts?

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