Fasteners Flashcards
What is the form of a screw?
One complete contour between corresponding points on the crest
What is the crest of a screw?
The prominent point of the thread at the top
What is the root of a screw?
The bottom of the thread
What is the flank of a screw?
The slope between the root and crest
What is thread angle?
The angle between two adjacent flanks
What is the major diameter for a screw?
Male threads- diameter of the crest
Female threads- diameter of the root
What is the minor diameter of a screw?
Male thread- diameter of the root
Female thread- diameter of crest
What is the depth of a screw?
Radial distance between the root and crest
What is the pitch of a screw?
The distance between two crests or roots on the thread
What is the lead of a screw?
The distance covered in one rotation
What is the run out of a screw?
Where the minor diameter equals the major and merged into the plain shank
What are the the three old screw systems?
British association (BA) British standard (BS) American National (AN)
What are the three parts to BS screws?
BSW (whitworth)
BSF (fine)
BAP (pitch)
What is the max diameter and thread angle for BA screws?
1/4 diameter
47.5 degrees
What replaced the three screw systems?
The universal system
UNF fine
UNC coarse
UNEF extra fine
What is the thread angle for universal and American standards?
60
What is stronger in a hole, a fine or coarse screw?
Fine screw
What are the three types of transmission thread profiles?
Square
Buttress
Acme
Which thread type can only transmit power in one direction?
Buttress
Definition of a bolt?
Is tightened with a nut
Definition of a screw?
Tightened into a threaded hole by the head
If not stated, what is the minimum amount of the bolt or screw that should be extending through the nut?
1/32” including full chamfer
How is steel represented on a bolt?
X
What does a triangle symbolise on a bolt?
The material is of close tolerance
How is corrosion resistant steel indicated on a bolt?
Single dash
How is aluminium represented on a bolt?
Pair of dashes
What does the first of the last three digits represent in a bolt part number?
If it’s plated, or if the head or shank is drilled
What does the second last digit in a bolt part number represent?
The grip length in 1/16”
What does the last digit in a bolt part number represent?
How much over size it is
X- 1/64”
Y-1/32”
How long should the grip length of a bolt be?
Equal to the material thickness
How many washers can be used to adjust grip length?
Up to three maximum
What is a stud?
A piece of rod threaded at either end with a plain section in the middle
How can studs be fitted?
Lock nuts
Stud box
Stud insertion/removal tool