Fasteners Flashcards
What is a right hand thread
A thread cut in a clockwise direction most screws are right hand
What is left hand thread
A screw cut in the anti clockwise direction
What is the lead
Distance moved in one complete revolution
What is the form
The shape of one complete contour
What is the crest
The prominent point in the thread
What is the root
The bottom point in the thread grove
What is the flank
The slope of the thread between the roots and crest
What is the thread angle
Angle between 2 adjacent flanks
What is the major diameter
On male crest to crest
Female root to root
What is the minor diameter
Male root to root
Female crest to crest
What is the pitch
The distance of crest to crest on the same pitch
What is the run out
There the thread begans to Become straight
What is the depth
Radial distance between the food and the crest
What is a single start
Lead = pitch
In one resolution the distance travel so one crest to crest
What is a 2 start
Lead = 2x pitch
What is BS
British standards
What is BA
British association
What is AN
American national
What is a BSW
British standards whitworth
For general purpose
Angle of 55
What is BSF
British standard fine
Finner version of BSW has more threads and less diameter
Has resistance to vibration
55 angle
What is a BSP
British standard pipe Fine pitch Used for pipeline couplings Strong connection Can be tapered to make a pressure tight joint 55 angle
What is BA
British association
47.5 angle
Only in sizes 1/4 inch
Use for smaller mechanical or electrical parts
Range from sizes 0 to 10 the smaller the number the higher the thread
What is ANC and ANF
American national coarse and fine
60 angle
What is a UF
Unified thread ID by machines symbol and mark 60 angle UNC – Unified National Coarse • UNF – Unified National Fine • UNEF – Unified National Extra Fine
What is TPI
Thread per inch
What is a deeper thread
Less threads per inch
What is the distance between course and fine pitch
A coarse pitch thread has a greater lead than a fine pitch thread of the same major diameter
What is a buttress thread
Can only transmit power in one direction
What is the thread depth that should be showing
1/32 inch
0.8mm
What material is a boot with a cross on
Steel
What material is a bolt with a line on
Crosion resistant steel
What material is a bolt with 2 dashes
Aluminium
What is U in a part number
Unplated
What is a - on a bolt identification
Plated
What is D on a bolt identification
Drilled shank
What is H on a bolt identification
Drilled head
What is single number on a bolt identification
Grip length , measured in 16th
What is X on a bolt identification
1/64inch oversized
What is Y on a bolt identification
1/32 inch oversized
What is NE on a bolt identification
Long threaded
Boeing only
What is NF on a bolt identification
Short threaded
Boeing only
What do material less than 2.4mm
No threads inside hole
What do materials with greater than 2.4 mm have
Two threads inside the hole
What is the max number of washes used
3
What is the grip length of a bolt be equal to
The material thickness
What are the 4 types of studs
Standard
Waisted
Stepped
Shouldered
What is a stud
A price is rod with a thread at each end and with a plain portion in the middle
Why is stranded stud used
Most widely used
Same diameter
What is a waisted stud
Same strength
Saves weight
What is a stepped stud
Provide a strong Anchorage
Used for soft material
What is shouldered stud
Maximum rigidity is required against the lateral strength
What is a stud box
Used to fit a stud
Screwed at one end
Used into price
Stud removed
What is an stud insertion or removal tool
Insertied into thread by hand
Inserting tool places over the protruding end
Locked together
What is a lock nut
Screwed into outer frame of the stud and locked firmly together
Screwed into housing
What is filed flat
Removal of damaged studs
Only if surface is protruding
What is ezi-out
When a stud is broken below the surface
Drill hole in stud
Remove using a ezi-out tool
What is structural screw
Used for assembly
Made of alloy steel
Are Heat treated
Same strength as bolts , only have different heads
What is flush head
Flush-head machine screws are used in countersunk holes where a flush finish is desired. These screws are available in 82 and 100 degrees of head angle and have various types of recesses and slots for driving.
What is round head
Round-head machine screws are frequently used to assemble highly stressed aircraft components.
What is fillister head
Fillister-head machine screws are used as general-purpose screws. They may also be used as cap screws in light applications, such as the attachment of cast aluminium gearbox cover plates.
What is socket head
Socket-head machine screws are designed to be screwed into tapped holes by internal wrenching. They are used in applications that require high-strength precision products, compactness of the assembled parts, or sinking of the head into holes.
What is a self tapping screw
cuts its own internal threads as it is turned into the hole. Self-tapping screws can be used only in comparatively soft metals and materials.
What is a machine self tapping screw
Used for removable parts
Nameplates castings
Hole needs to be pre drilled
What is sheet metal slef tapping screws
Temporary attaching sheet metal for riveting
What is a non slef locking nut
These are used with drilled-shank hex-head bolts, clevis bolts, eye bolts or struts and are designed to accommodate a cotter pin or wire locking as a means of safetying.
What is a shear castle nut
Used only for shear load on clevis bolts.
These nuts are available in cadmium-plated nickel steel, corrosion-resistant steel and in 2024 aluminium alloy.
What is a castle nut
These nuts are designed to fit on standard airframe bolts and may be used when the bolt is subjected to either shear or tensile loads. They are made from the same material as the shear castle nut.
What is a slotted engine nut
This nut is designed for use on an aircraft engine and is not approved for airframe use. It is made of heat-treated steel.
What is a wing nut
Wing nuts are intended for use on hose clamps and battery connections, etc., where the desired tightness is ordinarily obtained by the use of fingers. They are made of either cadmium-plated steel or brass.
What is a locking nut
A lock nut is a thin, plain nut which is tightened down firmly onto the main, plain nut. This friction wedges the threads to prevent them both slackening.
What is a nylon stiffnuts
This nut has an unthreaded nylon insert permanently housed at the outer end. As the bolt threads engage the insert, the nylon is compressed into them, setting up a friction which prevents the nut unscrewing. Low temperature use only.
What is a oddie stiffnut
Oddie stiffnuts have six tongues at their outer end which are bent inwards
to form a circle slightly less in diameter than the root of the bolt thread. As the bolt passes through the nut, the tongues are pushed upwards, applying a locking load onto the bolt thread.
What is a Aerotight and Philidas Stiffnuts
These nuts have slotted locking extensions which are closed during manufacture to put the screw-thread out of alignment. As the bolt engages and realigns the extension thread, a grip is produced which provides a friction lock.