6.5- Fasteners Flashcards
A thread formed on a cylinder is a straight or parallel thread, what is called on a conical part?
Tapered thread.
What is the definition of screw form?
Shape of the thread from crest to crest.
What is the crest of a thread?
The most prominent part.
What is the root of a thread?
The bottom point of the thread groove.
What is the flank of a thread?
The slope of the thread between root and crest.
What is the thread angle?
The angle between two adjacent flanks.
What is the major diameter of a thread.
Male- diameter of crest
Female- diameter of roots
On a male thread what is the major diameter also referred to as?
Crest or normal diameter.
What is the depth of a thread?
The radial distance between root and crest.
What is the pitch of a thread?
The distance between adjacent crests.
What is the lead of a thread?
The distance a crest travels in one complete revolution.
What is thread run out?
The part of the thread which starts at the minor diameter until it equals the major and meets the plain shank of the fastener. (Basically the last bit of the thread).
When you increase amount of starts in a fastener (threads) what happens to how far it travels in one revolution?
It travels further, for example a 2 start will travel twice as far as a single start.
What did British and Americans use as their screw standards.
British- BS and BA
America- AN
What have the the UK and US thread systems been replaced by for one system?
Unified thread.
What do the three British standard thread forms BSW, BSF and BSP stand for?
British standard Whitworth
British standard fine
British standard pipe.
What is the thread of BSW.
Coarse with a thread angle of 55 degrees.
What is the thread of BSF.
Finer version of the coarse BSW.
What is the thread of BSP.
Even finer version of BSW and BSF.
What size is BA threads used for?
Anything below 1/4, its thread angle is 47.5 degrees.
What are BA sizes expressed in?
0-10, the larger the number the smaller the thread.
What is the major diameter of a BA 0 thread?
0.236 inches.
What are the two types of American national thread (AN).
ANC- coarse
ANF- fine
What are the three versions of unified threads?
UNC- Coarse
UNF- Fine
UNEF- Extra fine