Exercise 24. Ask questions and use the words in italics in your answers. The words in brackets will help you. 1. A metal workpiece is placed
in a die (where). 2. Heated liquid material
is usually poured
into a mold (where). 3. Dies must be
precisely designed (how).
4. Dies should withstand
tremendous forces and pressure (what). 5.
In the end of the operation the flash is removed (when).
Exercise 25. Read the following dialogue, sum up the information and act out a similar dialogue. FORGING A.: Do you know what forging is?
B.: Sure. Forging is one of the oldest known metalworking processes. Tradi-
tionally, many metal tools were made by heating iron bars in a fire called a
forge, and then they were worked or shaped by hammering it.
A.: Absolutely. Forging was performed by a smith using hammer and anvil.
It is still in use though nowadays it is done either with modern presses or
with hammers powered by compressed air, electricity, hydraulics or steam.
B.: I agree with you. Forging has lived over centuries to become a facility with
engineered processes, production equipment, raw materials and products
to meet the demands of modern industry.
A.: I wonder if there really exist ‘cold’, ‘warm’ or ‘hot’ forging.
B.: You see, some metals may be forged cold, but iron and steel are almost
always hot forged.
A.: Are there any advantages of ‘hot’ forging?
B.: Hot forging prevents the work hardening that would result from cold forg-
ing, which would increase the difficulty of performing secondary machin-
ing operations on the piece. Are you aware of the fact that forged parts
usually require further processing to achieve a finished part?
A.: Yes, I am. But I know that work hardening may be desirable in some cir-
cumstances.
B.: Then other method of hardening the piece is used, such as heat treating,
which is generally more economical and more controllable.
A.: So, I see, engineers have to choose the type of forging to serve the given
purpose.
