Forging hammers are commonly used for impression-die forging and can be used for a variety of forging operations. In forging hammers a heavy ram containing the upper die is lifted by steam pressure or air pressure, then driven or allowed to fall on the workpiece which is placed on the bottom die, which in turn is supported on the anvil. Repeated blows are struck until the desired metal movement is accomplished.

The hammer rests on an anvil, which acts as a large inertia block and extends underground a considerable distance. The weight of anvil is about 20 times the weight of the ram.

The various types of forging hammers commonly used are:

(i) The board hammer (gravity drop),


(ii) The steam hammer (steam lift and steam drop),

(iii) The air-lift hammer (the ram lifted by air gravity drop),

(iv) Impactor (depending on the size, the forging hammers may be of single or open-frame as well as double-housing type).

Gravity Drop Hammers

Fig. 5.38 shows the three types of forging hammers commonly used. Gravity drop hammers are of 3 kinds. In board hammers the tup is lifted by a board which is trapped between rotating cylinders. In belt lift hammers the tup is lifted by a belt driven by a rotating drum.


In air lift hammer, tup is lifted by air and falls under gravity but in double acting hammer, air pressure also acts during falling making it have greater energy. In counter blow hammers, top and bottom tup are interconnected and move towards each other during forging. This hammer needs less bulky foundation but other types and bulky foundation.

Counter Blow Hammer

Double Acting Hammer

In the board hammers, the ram is attached to a set of hardwood boards. The boards and ram are lifted by a set of counter rotating rolls, and then released. The energy of ram is the mass and velocity of the freely falling ram and die. The operation continues as long as the operator holds the foot treadle downward.


Board drop hammer is generally considered superior to the steam hammer for producing drop- forgings of small and medium size. When the work is heavy and requires a great deal of “breaking down” or drawing, or even when the forgings are light, but have their sections that cool quickly, thus requiring sharp rapid blows, the steam hammer will usually given better results than a board drop hammer.

Upto 60—80 strokes per minute are obtained and the falling weight (by which hammers are rated) varies from 300 to 600 kg. The ram contains a dovetail to which the die is fastened. The anvil is protected from shock and wear by a sow block (also known as anvil cap or shoe) which is used to hold the anvil die.

In the steam hammers, the ram is raised by steam and driven toward the work piece by steam or air pressure. Since the striking force is due to the weight of the falling body plus the force of the steam or air pressure, it can be varied over a wide range. This hammer is large and sturdier and ranges from 800 to 2000 kg capacity.


In the air lift hammers, the energy for forging is provided by the falling weight, and for raising the ram by an air cylinder. The energy delivered can be varied by varying the length of the stroke.

An impactor (horizontal, counter-blow hammer) is a special forging equipment in which the mutually opposed rams (impellers) move (by pneumatic pressure) in from the sides simultaneously to strike successive blow on the workpiece, which is positioned in the impact plane where the two dies collide.