Student must include this instruction when submitting the assignment.
Instruction:
 Read chapter 14 of Kalpakjian, Serope. Manufacturing Engineering and
Technology
Englewood Cliffs, NJ: Prentice Hall – Fourth Edition, 2001. ISBN # 0201-36131-0
 Complete the homework assignment below.
 Do not use attached file for homework assignment. You must copy and
paste all data in your email.
 Type answer below each question.
 Reduce Grade: if the assignment is received after the due date, it will be
deducted by 1 letter grade.
 NO grade will be assigned for homework with more than 7 days late or
improper format as indicated above.
Manufacturing Processes - INMT-1249 - Assignment 04
QUESTIONS
14.1 What is the difference between cold, warm, and hot
forging?
Answer (from page #__342___):
Forging may be done at room temperature (cold forging) or at elevated temperatures
(warm or hot forging, depending on the temperature.) Because of the higher strength of
material, cold forging requires greater forces, and the work piece materials must have
sufficient ductility at room temperature. Cold-forged parts have good surface finish and
dimensional accuracy. Hot forging requires smaller forces, but it produces dimensional
accuracy and surface finish that are not as good.
14.2 Explain the difference between open-die and
impression-die forging.
Answer (from page #_342, 344____):
Open-die forging is the simplest forging process. Advantages of open die forging are
simple, inexpensive dies; useful for small quantities; wide range of sizes available; good
strength characteristics.
In impression-die forging, the work piece acquires the shape of the die cavities
(impressions) while being forged between two shaped dies.
14.3 What does breaking down a cast ingot mean?
Answer (from page #_____):
14.4 Explain the difference between fullering, edging, and
blocking.
Answer (from page #_345____):
In fullering, material is distributed away form an area; in edging, it is gathered into a
localized area. This part is then formed into the rough shape of a connecting rod by a
process called blocking, using blocker dies.
14.5 What factors are involved in precision forging?
Answer (from page #_346____):
The process requires higher-capacity equipment, because of the greater forces required to
obtain fine details on the part. Precision forging requires special and more complex dies,
precise control of the billet’s volume and shape, accurate positioning of the billet in the
die cavity, and hence higher investment.
14.6 Describe orbital forging and explain how it differs from
conventional forging operations.
Answer (from page #__350___):
Orbital forging is a process in which the upper dies moves along an orbital path and
forms the part incrementally. The operation is similar to the action of a mortar and
pestle. Typical components forged by this process are disk-shaped and conical parts,
such as bevel gears.
14.7 What type of parts is rotary swaging capable of
producing?
Answer (from page #__352___):
It can form internal profiles on a tubular work piece. The swaging process can also be
used to assemble fittings over cables and wire; in such cases the tubular fitting is swaged
directly onto the cable.
14.8 Explain the features of a typical forging die.
Answer (from page #__354___):
For most forgings, the parting line is usually at the laregest cross-section of the part. For
simple symmetrical shapes, the parting line is normally a straight line at the center of the
forging, but for more complex shapes the line may not lie in a single palne. The dies are
then designed in such a way that they lock during engagement, in order to avoid side
thrust, balance forces, and maintain die alignment during forging.
Features are:
Flash, Gutter, Parting line, Land, Rib, Web, Fillet, Corner, Trim Line.
14.9 Why is intermediate shape important in forging
operations?
Answer (from page #__353___):
(Intermediate shape) the work piece should be shaped so that it properly fills the die
cavities. The importance of performing can be appreciated by noting how a piece of
dough is preshaped to make a pie crust or how ground meat is preshaped to make a
hamburger.
14.10 How is forgeability defined?
Answer (from page #_355____):
Forgeability is generally defined as the capability of material to undergo deformation`
with-out cracking.
14.11Explain what is meant by "load limited," "energy limited,"
and "stroke limited," as these terms pertain to forging
machines.
Answer (from page #__357___):
Load limited, or load restricted. In other words, a press stops if the load required exceeds
its capacity.
The speed varies from a maximum at the center of the stroke to zero at the bottom of the
stroke, so they are stroke limited.
Screw presses derive their energy from a flywheel; hence they are energy limited.
14.12 What is flash?
Answer (from page #_344____):
Formation of flash, which is excess metal that is subsequently trimmed off.
14.13 Why is hubbing an attractive alternative to producing
simple dies?
Answer (from page #__349___):
Hubbing consist of pressing a hardened punch, having a particular tip geometry into the
surface of a block of metal. The cavity produced is then used as a die for forming
operations, such as occur in the marking of tableware. The die cavity is usually shallow,
but for deeper cavities, some material may be removed from the surface by machining
prior to hubbing.
14.14 Explain the principles of different forging machines.
Answer (from page #__359___):
Several considerations are important in the selection of forging machines: forces or
energy requirements; the size, shape and complexity of the forging; the strength of the
workpiece material; and the sensitivity of the material to the rate of deformation.
Additional factors include production rate, dimensional accuracy, maintenance, operating
skills required, noise level, and cost.
14.15 Explain the concerns in the layout of upsetting dies.
Answer (from page #__343___):
The open-die forging process can be depicted by a solid workpiece placed between two
flat dies and reduced in height by compressing it. This process is also called upsetting or
flat-die forging. Deformation barreling is caused primarily by frictional forces at the dieworkpiece interfaces that oppose the outward flow of the materials at these interfaces.
Barreling can be minimized if an effective lubricant is used.
14.16 Describe the capabilities and limitations of common
forging equipment.
Answer (from page #__340___):
Simple forging operations can be performed with heavy hand hammer and an anvil, as
was traditionally done by blacksmiths. Most forgings, however, requires a set of dies and
such equipment as a press or a forging hammer. Unlike rolling operations, which
generally produce continuous plates, sheets, strip, or various structural cross-sections,
forging operations produce discrete parts.
14.17 What is the difference between piercing and punching?
Answer (from page #_349____):
Piercing is a process of indenting (but not breaking through) the surface of a workpiece
with a punch in order to produce a cavity or an impression.
Punching, to produce a hole in the part
======================= End of Homework Assignment
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