M6.5 Fastners Flashcards
How can you measure the screw pitch
By using a screw thread pitch gauge
What does class 1 mean
Loose fit
What does class 2 mean
Free fit
What does class 3 mean
Medium fit
What does class 4 mean
Close fit
What does class 5 mean
Tight fit
Whose mum is class 1 fit
Lewis’s mum cus she’s a loose fit
What class are aircraft screws normally in
Class 2
What is the maximum temperature low temperature locking nuts can withstand?
121 degrees
What is the crest on a screw
The prominent point of the thread
What is the temperature high temperature self locking nuts will act at?
121 degrees plus
What is the root of a screw
Bottom point of the thread groove
Where are slotted engine nuts used?
Engine only
What is a flank on a screw
The angle of the slope between the root and crest
What are anchor nuts used for?
Pannels regularly removed
Where are tinerman nuts used?
Any area which chance of magnetic interference
What is a stud (don’t say megs dad)
Shaft threaded on both ends
What is a thread angle
Angle between two crests
Describe a standard stud thread
Same throughout
Describe a waisted stud thread
Threaded each end, strength is retained, weight saved
What is the major diameter (screws) on a male and female
Crest to crest on male
Root to root female
Describe a stepped studs thread
Provide a stronger anchorage when used for softer material
Describe a shouldered stud thread
used when rigidity is required lateral stress
What are the 3 ways stud insertion are removed?
. Stud box
. Stud insertion tool
. Lock nuts
What is a heat coil insert and what does it do?
. Repairs stripped thread
. Must be 1/2 pitch below surface
What is a minor diameter (screws) on male and female
Root to root on male
Crest to crest on female
Name the 3 types of screw and describe them
. Machine screws - most common, structural parts, fairings
. Structural screws - same bolt strength, can be heat treated
. Self tapping screws - light weight material only, thin metal sheets
What is a pitch (screw)
The distance of one revolution
What are dowels?
Provide precision to alignment
What does BSW
British standard Whitworth
What does BSF stand for
British standard fine
What does BSP stand for
British standard pipe
What are the thread angles of BSW, BSF, BSP
55^
When would you use BSF
When part is subject to vibration
What does BA stand for
British association
What is the Thread angle of BA and the diameter
47.5^
Less than 1/4” diameter
What does ANC and ANF stand for
American national coarse - flat crest and root
American national fine
What the “x” indicate on top of a bolt
That it’s a steel bolt
What thread angle is ANC and ANF
60^
What type of thread profile only travels in one direction
Buttress
What is the thread angle for United national coarse, fine and extra fine
60^
What are the three bolt profiles
Acme
Buttress
Square
What are the two types of threads
Course and fine
What the thread angle of a unified National threads?
60 degrees
What’s the thread angle of American thread forms
60 degrees
Which one out the British thread forms has a different thread angle and what is that angle
Ba and 47.5
What’s the thread angle of British thread forms
55 degrees
What’s the major and minor diameter of a female thread
Minor- crest to crest
Major- root to root
What’s the major and minor diameters of a male thread
Major- crest to crest
Minor- root to root
What is a square thread profile used for
Ideal for power transmission
What’s the crest, root and flank of screw
Crest is the prominent point
Root is the lowest point
Flank is the angle of the slope
What do the 5 classes mean
1 is loose
2 is free
3 is medium
4 is close
5 is tight
What’s used to measure a thread pitch
Thread pitch gauge
What is an advantage of ACME thread profile
Stronger than square
What is Butress thread profile used for
For handling heavy forces, can only travel in one direction
What are close tolerance bolts used for
When subjected to pounding loads
When are eyebolts used
When subjected to tension loads
What does H mean on a Bolt
A Drilled head
When are Clovis bolts used
When subjected to shear loads
What does the double dash on a bolt head mean
That it’s made from aluminium
What’s the triangle on a bolt head mean
That it’s close tolerance
What’s a single dash mean on a bolt head mean
That it’s made from CRES metal (corrosion resistant)
What are the two different types of nuts
Self locking
Non self locking
What does the cross mean in material identification?
Steel
What does a line in the bottom left corner mean in material identification?
Corrosion resistant steel
What does two lines mean in material identification?
Aluminium
what temp do low temperature self locking nuts operate at
121 degrees max
What does A mean when on a bolt
Drilled hole need to check
What does it mean if there’s a triangle when identifying materials?
Close tolerance
What is a Clevis bolt and when is it used
Round snapped head
Only used when load applied is shear
What’s the difference between the materials in a low temp self locking nuts vs a high temp self locking nut
Nylon insert in low temp
High temps made from same metal
When is an eye bolt used
Where external load tension applied
What is a drilled head engine bolt and when is it used
Have a thick head that has small holes in each of the flats and centre of the head
Only used in engine
What’s the difference between a slotted engine nut and a castle nut
Slotted engine nuts can only be used on engine whereas castle nuts can be used on structure
What is a close tolerance bolts and when are they used
Used in areas subject to pounding or where load is required to be riveted and bolted
Identified by triangle mark on their heads
What’s the reason for using waisted studs
Used for when weight saving is needed
What’s the reason for using shouldered studs
Gives lateral stability
When is an internal wrench bolt used
High tensile steel bolts
Used for high tensile strength
Spreads stress out
What is precision airframe bolts and when is it used
Grap length = 1/16 inch increments
Used if standard ms bolt is either too long or too short
Why are hell coil inserts used
Used when the thread has worn away to replace previous threads
