Threads Flashcards
(OD)=(size# x .013)+.060
machine screw thread designation
TDS=MD-pitch
tap drill size formula
find pitch of imperial thread
1/tpi=pitch for imperial thread
nut used when appearances are important
acorn nut
nut kept in position using a cotter pin or wire
castellated nut
nut used to spread the clamping pressures over a greater area of the workpiece
hex flange nut
nut used with machine screw
square nuts
nut have a deformed or crimped thread at the top of the crown that provides the locking force against the mating thread
prevailing torque lock nuts
nut used in application requiring frequent removal and retightening
wing nut
nut used in light application, the spring action of the two ridges provides a modest locking force
speed nut
nut thinner than hex nut, paired with hex nut to lock into place
jam nut
nut has a nylon or plastic to keep it tight
nylon lock nut
nut used when high preloads are required and where dialation of the nut must be prevented
hex thick nut
nut has a built in external lock washer
flange lock nut
nut, very thin used on electrical panel and breaker boxes
panel nut
the letter A in regards to unified threads stands for
external threads - bolts
the letter B in regards to unified threads stands for
internal threads - nuts
class of threads used for general and commercial bolts
2
class of threads used for aerospace and precision tools
3
class of threads used for there high tolerance for fast assembly
1
E-H vs e-h
bolts vs nuts
which letter has a larger allowance for nuts and bolts
e or h
E
the largest diameter of a screw thread
major diameter
the smallest diameter of a screw thread
minor diameter
the diameter at which the thickness of the thread equals the thickness of the space between the thread
pitch diameter
at the top of the helical ridge known as the major diameter
crest
at the bottom of the space between the threads known as the minor diameter
root
the distance from one point on one thread to the same point on the next thread
pitch
the angled side of a thread connecting the crest and the root
flank
the axial distance a nut advances on a screw thread after one complete turn
lead
the included angle between the flanks of a thread
thread angle
the thickness of a thread measured at the pitch diameter
thread thickness
commercial fasteners all use what thread form angle
60 degrees
thread form used for precise measuring tools such as micrometers
special 60 fine
thread form is standard use for transmitting power and motion in machinery, has a 29 degree thread angle and root and crest are flat
american national acme thread
thread form used as a driver for gears to transmit angular motion, has a 29 degree thread angle, has a narrow root and crest
brown and worm thread
thread form used in applications involving exceptionally high stresses in one direction, has a pressure flank at 90 degree to the thread axis and a 45 degree clearance flank
buttress thread
pipe threads angle is
60 degree
nut used for stability in high temperature applications and with high strength structural bolts
2H nut
nuts used for shackles, u bolts, these nuts are furnished only with fine threads and hardened
high nuts
the maximum tension that an object can sustain and still return to its original shape and be fully fuctional
elastic limit
the highest recommended tensile load for that fastener
proof load
the point which a fastener suffers permanent deformation when a tensile load is applied
yield point
the amount of continuous shear force that a fastener can withstand before breaking
shear strength
resistance to fracture or the amount of energy a substance absorbs before it breaks
toughness
the ability of a material to resist penetration
hardness
the characteristic of a material to be shaped or moulded easily
malleability
how much a material can be deformed or drawn before it breaks
ductility
if a material has the ability to be stretch without deformation
elasticity
lubricating a fasteners increases the amount of _____ when torquing to the same settings
preload
Lubricating a nut before installation can reduce tension by how much
7%
