Fasteners

Question 1

functions of fasteners

Answer 1

join components together
constrain relative movement
transmit forces between components

Question 2

general classifications of fasteners

Answer 2

permanent fasteners
removable fasteners
reusable fasteners
non-reusable fasteners

Question 3

key functions

Answer 3

transmit torque from shaft to gear (or vice versa)
prevent relative rotation

Question 4

types of keys

Answer 4

square key
flat key
gib head
Pratt & Whitney key
woodruff key

Question 5

advantage of a flat key

Answer 5

allows for space constraint

Question 6

why the hell are gib head keys like that?

Answer 6

they’re driven into position

Question 7

advantage of Pratt & Whitney key

Answer 7

avoids stress concentrations

Question 8

advantage and disadvantage of woodruff key

Answer 8

can tilt in the keyseat - easier assembly
more complex to machine

Question 9

‘rule of thumb’ for deciding key width

Answer 9

make key width 0.2d - 0.25d where d is the diameter of the shaft
then adjust length to get desired stress levels

Question 10

most common manufacture method for keyseats

Answer 10

end milled slot

Question 11

what manufacture method should you use to get a keyseat with squared corners?

Answer 11

plain milling

Question 12

what form of milling can be used to avoid a radius?

Answer 12

none

Question 13

how are keyways cut?

Answer 13

broaching

Question 14

when are splines used?

Answer 14

very high torque applications
applications where we want to permit some axial sliding

Question 15

alternatives to keys

Answer 15

solid axial pin
solid transverse pin
spring/expansion pin

Question 16

type of fit required for a solid axial/transverse pin

Answer 16

press fit

Question 17

advantage of spring pin

Answer 17

fit is less critical

Question 18

pin function

Answer 18

stops the thingy sliding off the whatsit

Question 19

basic steps of rivet installation

Answer 19

hole drilled through both parts
rivet inserted into hole
rivet head gets deformed

Question 20

advantage of rivets

Answer 20

unlikely to loosen (require plastic deformation)

Question 21

why are large rivets heated before deformation?

Answer 21

to soften them
cooling causes shrinking which creates a preload

Question 22

a ________ is used to deform the head on a pop rivet

Answer 22

internal madrel

Question 23

type of fastener used for axial location

Answer 23

circlip (/retaining ring)

Question 24

circlips cannot be reused if they have been ________

Answer 24

plastically deformed

Question 25

basic operation of a snap fit fastener

Answer 25

head of clip is shaped to deform on insertion
clip ‘snaps’ into position after passing the locking feature

Question 26

advantage of a snap fit fastener

Answer 26

no tools required for assembly

Question 27

any deformation involved in the insertion of a snap fit much be ______

Answer 27

elastic

Question 28

what type of material is better suited for snap fits, and why?

Answer 28

polymers
low modulus = large elastic deformation