EMAE 160 EXAM QUESTIONS WITH
COMPLETE ANSWERS
What are the differences between fine blanking and standard sheet metal stamping?
- ANSWER-fine blanking = cutting sheet metal along a closed outline; the desired
product (blank) is the part cut out; (presses include hardened die punch and blanking
die, guide)
Standard sheet metal stamping = drives sharpened tool steel punch through sheet or
strip material into a die cavity. The finished part has predictable edge
How are most externally threaded fasteners manufactured? - ANSWER-machining,
cold forming/cold heading and manual die
What are the two systems used for measuring the hardness of heat-treated steels? -
ANSWER-burnell hardness no. and rockwell c scale
Explain the difference between liquid phase sintering and solid phase sintering when
describing the powdered metallurgy process - ANSWER-L = requires adding additive
to powder, which melts before matrix phase .
S = heat treatment of powder compacts at elevated temperatures.
Which process provides high material removal rate? - ANSWER-plasma arc cutting
What is the property that allows metals to be permanently deformed beyond yield
without failure by rupture or splitting? - ANSWER-Plasticity
Name 3 types of stress to which materials are subjected. - ANSWER-tensile,
compressive, shear
What is ultrasonic machining and can it be used for both metallic and nonmetallic
materials? - ANSWER-it is a vibrating, oscillating tool used to remove material from a
workpiece with the help of an abrasive slurry flowing freely between the workpiece
and tool. Can be used for every material.
(Advantages: little grinding pressure, good for brittle materials especially glass,
ceramics, semiconductors.)
Are applications of electron beam machining limited to metallic materials? Why or
why not? - ANSWER-Can only be used on metal bc electron melts metal. The
energy and power density can be controlled and high velocity electrons can be
concentrated to a narrow beam.
What type of indenter does a rockwell hardness testest ("C" scale) use to measure
the hardness of heat treated high-carbon steel? - ANSWER-120 degree diamond
cone
, In terms of the powdered metallurgy process, what is impregnation? - ANSWER-
filling a porous substrate to make it airtight. In powder metallurgy, impregnate inner
void prior to plating to reduce corrosion. Fill sintered component with lubricants
What machining process is appropriate for creating a square blind hole in a piece of
steel? - ANSWER-RAM EDM
What machining process is appropriate for creating anarrow slot (0.015' wide) in a 2
inch thick plate of hardened tool steel? - ANSWER-Laser beam cutting and water jet
cutting
What are the three basic steps in the conventional powdered metallurgy process? -
ANSWER-blending, compaction, sintering
Name the three basic types of Forging Operations. - ANSWER-open-die forging,
impression-die and flashless
Describe flash in relation to impression die forging. (extra question) - ANSWER-it is
excess metal squeezed out of die cavities
Does the flash produced in impression die forging serve a useful purpose? Is it
desirable? - ANSWER-Yes. Because it cools more rapidly than rest of material and it
is stronger than metal in die so it prevents additional flash from forming and forces
metal to fill die
Define spring-back in sheet metal bending. - ANSWER-tendency of metal to return to
its original position after bending pressures are removed. Sheet must be over-bent to
compensate.
Name 3 types of Forging Presses. - ANSWER-mechanical, hydraulic and screw.
Explain the difference between a mechanical press and hydraulic press for forging. -
ANSWER-Hydraulic presses = high pressure fluid + a piston = generate slow and
constant force.
Mechanical presses = uses toggles/cranks = produces a quick and varied preset and
reproducible stroke
Explain the differences between cold-rolled and hot-rolled steels. - ANSWER-cold-
rolled = rolled to final dimensions below re-crystallisation temperature (adv+disadv:
has tighter tolerances, better surface finish, usually smaller or stronger, more
expensive)
hot-rolled = rolled to final dimensions above recrystallization temperature
Is forging always in the vertical direction? - ANSWER-No for example forging press
can be positioned horizontally
How is a soda can made? - ANSWER-deep drawing (not 100% sure)
COMPLETE ANSWERS
What are the differences between fine blanking and standard sheet metal stamping?
- ANSWER-fine blanking = cutting sheet metal along a closed outline; the desired
product (blank) is the part cut out; (presses include hardened die punch and blanking
die, guide)
Standard sheet metal stamping = drives sharpened tool steel punch through sheet or
strip material into a die cavity. The finished part has predictable edge
How are most externally threaded fasteners manufactured? - ANSWER-machining,
cold forming/cold heading and manual die
What are the two systems used for measuring the hardness of heat-treated steels? -
ANSWER-burnell hardness no. and rockwell c scale
Explain the difference between liquid phase sintering and solid phase sintering when
describing the powdered metallurgy process - ANSWER-L = requires adding additive
to powder, which melts before matrix phase .
S = heat treatment of powder compacts at elevated temperatures.
Which process provides high material removal rate? - ANSWER-plasma arc cutting
What is the property that allows metals to be permanently deformed beyond yield
without failure by rupture or splitting? - ANSWER-Plasticity
Name 3 types of stress to which materials are subjected. - ANSWER-tensile,
compressive, shear
What is ultrasonic machining and can it be used for both metallic and nonmetallic
materials? - ANSWER-it is a vibrating, oscillating tool used to remove material from a
workpiece with the help of an abrasive slurry flowing freely between the workpiece
and tool. Can be used for every material.
(Advantages: little grinding pressure, good for brittle materials especially glass,
ceramics, semiconductors.)
Are applications of electron beam machining limited to metallic materials? Why or
why not? - ANSWER-Can only be used on metal bc electron melts metal. The
energy and power density can be controlled and high velocity electrons can be
concentrated to a narrow beam.
What type of indenter does a rockwell hardness testest ("C" scale) use to measure
the hardness of heat treated high-carbon steel? - ANSWER-120 degree diamond
cone
, In terms of the powdered metallurgy process, what is impregnation? - ANSWER-
filling a porous substrate to make it airtight. In powder metallurgy, impregnate inner
void prior to plating to reduce corrosion. Fill sintered component with lubricants
What machining process is appropriate for creating a square blind hole in a piece of
steel? - ANSWER-RAM EDM
What machining process is appropriate for creating anarrow slot (0.015' wide) in a 2
inch thick plate of hardened tool steel? - ANSWER-Laser beam cutting and water jet
cutting
What are the three basic steps in the conventional powdered metallurgy process? -
ANSWER-blending, compaction, sintering
Name the three basic types of Forging Operations. - ANSWER-open-die forging,
impression-die and flashless
Describe flash in relation to impression die forging. (extra question) - ANSWER-it is
excess metal squeezed out of die cavities
Does the flash produced in impression die forging serve a useful purpose? Is it
desirable? - ANSWER-Yes. Because it cools more rapidly than rest of material and it
is stronger than metal in die so it prevents additional flash from forming and forces
metal to fill die
Define spring-back in sheet metal bending. - ANSWER-tendency of metal to return to
its original position after bending pressures are removed. Sheet must be over-bent to
compensate.
Name 3 types of Forging Presses. - ANSWER-mechanical, hydraulic and screw.
Explain the difference between a mechanical press and hydraulic press for forging. -
ANSWER-Hydraulic presses = high pressure fluid + a piston = generate slow and
constant force.
Mechanical presses = uses toggles/cranks = produces a quick and varied preset and
reproducible stroke
Explain the differences between cold-rolled and hot-rolled steels. - ANSWER-cold-
rolled = rolled to final dimensions below re-crystallisation temperature (adv+disadv:
has tighter tolerances, better surface finish, usually smaller or stronger, more
expensive)
hot-rolled = rolled to final dimensions above recrystallization temperature
Is forging always in the vertical direction? - ANSWER-No for example forging press
can be positioned horizontally
How is a soda can made? - ANSWER-deep drawing (not 100% sure)
