Deck 28: Mechanical Assembly

Question 1

Which of the following are reasons why mechanical assembly is often preferred over other forming processes (two best answers):

A)does not require highly skilled workers
B)ease of assembly
C)ease of disassembly
D)economies of scale
E)involves melting of the base parts
F)specialization of labor

Answer 1

does not require highly skilled workers
ease of assembly
ease of disassembly

Question 2

The technical distinction between a screw and a bolt is that a bolt is designed to be assembled into a blind threaded hole:

Answer 2

False

Question 3

Screws and bolts can be specified in either metric standards or U.S.standards.The metric standard specification consists of the nominal major diameter followed by which one of the following:

A)head style
B)length
C)number of threads per inch
D)pitch

Answer 3

pitch

Question 4

Which one of the following types of screws is made of higher strength materials:

A)cap screws
B)machine screws

Question 5

A self-tapping screw derives its name from the fact that it does not require a pre-existing hole in the workpart:

Question 6

Most externally threaded fasteners are produced by which one of the following processes:

A)cold forming
B)cutting the threads
C)milling the threads
D)tapping
E)turning the threads

Question 7

The strength of a threaded fastener is generally specified by which of the following measures (two best answers):

A)Brinell hardness
B)modulus of elasticity
C)proof strength
D)shear strength
E)tensile strength
F)torsion strength
G)yield strength

Question 8

Which of the following methods and tools are used for applying the required torque to achieve a desired preload of a threaded fastener (three best answers):

A)arbor press
B)preload method
C)sense of feel by a human operator
D)snap fit
E)stall motor wrenches
F)torque wrench
G)use of lockwashers

Question 9

Which of the following are the common ways in which threaded fasteners fail during tightening (two best answers):

A)excessive compressive stresses on the head of the fastener due to force applied by the tightening tool
B)excessive compressive stresses on the shank of the fastener
C)excessive shear stresses on the shank of the fastener
D)excessive tensile stresses on the head of the fastener due to force applied by the tightening tool
E)excessive tensile stresses on the shank of the fastener
F)stripping of the internal or external threads

Question 10

One of the advantages of rivets as an assembly method is that no special alteration of the parts to be assembled is required:

Question 11

Rivets are used primarily for butt joints:

Question 12

The difference between a shrink fit and an expansion fit is that in a shrink fit the internal part is cooled to a sufficiently low temperature to reduce its size for assembly, whereas in an expansion fit, the external part is heated sufficiently to increase its size for assembly:

Question 13

Advantages of snap fit assembly include which of the following (three best answers):

A)components can be designed with features to facilitate part mating
B)ease of disassembly
C)no heat affected zone
D)no special tools are required
E)parts can be assembled quickly
F)stronger joint than with most other assembly methods

Question 14

The difference between industrial stitching and stapling is that the U-shaped fasteners are formed during the stitching process while in stapling the fasteners are preformed:

Question 15

From the standpoint of assembly cost, it is more desirable to use many small threaded fasteners rather than few large ones in order to distribute the stresses more uniformly:

Question 16

Which of the following are considered good product design rules for automated assembly (two best answers):

A)design the assembly with the fewest number of components possible
B)design the product using bolts and nuts to allow for disassembly
C)design with many different fastener types to maximize design flexibility
D)design parts with asymmetric features to mate with other parts having corresponding (but reverse) features
E)limit the required directions of access when adding components to a base part