|
SKETCH |
TITLE |
COMMENTS |
 |
SQUARE |
Commonly found on cup bolts;
also can be seen on raised countersunk (plow bolts/earth-moving)
and hexagon (pump bolts).
The square is used to retain the head while the mating nut is
tightened. |
 |
SHOULDER |
Normally round and normally
associated with hexagon heads.
Often is used to allow a retained part of the assembly to
rotate, eg: motor mower blades, tilta-door hinges.
Can also be used where a component in the assembly is made from
crushable material which would not stand up to the tightened
clamp force. |
 |
OVAL |
Usually associated with cup
heads, agricultural and railway applications;
also found on guardrail bolts.
Used as a retention device in a slotted hole. |
 |
WASHER RECESS |
Found usually on
self-drilling building fasteners; used to retain a neoprene or
plastic sealing washer. |
 |
FLANGE SERRATED
(Whiz-Lock) |
Hardened serrated teeth
ramped to bite into mating surface upon loosening.
Used in high vibration applications, particularly automotive;
also used on nut products.
With teeth ramped in the opposite direction, will act as a paint
or coating remover and give excellent electrical contact. |
 |
NIBS |
Less aggressive than
serrated, used on smaller fasteners to scrape paint or surface
coating to give improved electrical contact.
Often associated with mush or truss heads. |
 |
HIGH FIX
(High Grip) |
A reverse thread applied to
the shank just below the head allows a self-drilling building
fastener to grip the crest of the sheeting material assisting
the washer to achieve an improved seal. |
 |
COUNTERSINK RIBS |
Allows the screw to
self-countersink the work piece on assembly, giving a flush
finish.
Flower heads which have notches on the outer edge, similarly
ream a seating hole, allowing them to self-embed. |
