MILLWRIGHT REVISED EXAM 2024/2025 QUESTIONS
WITH 100% CORRECT ANSWERS
What does(3/4''-10 unci -2a x 1 1/2'' )stand for? - 3/4''= Nominal diameter
10 = Threads per inch
UNC = thread style (Unified national Course)
2= Class of fit
A= External thread (b= internal thread)
1 1/2''= length (depth of full threads in hole)
class of fit 1,2,3,4,5&6 - class 1 fit= maximum looseness in mating threads
class 2 fit= average fit little play in mating threads
class 3 fit= no looseness in mating threads.
class 4 fit= precision threads, usually cut and ground
class 5 and 6 fit= embellishments of class 4, but the most precise and accurate threads.
what does M8x1.25x50mm stand for? - M= Metric
8= nominal diameter in mm
1.25= the pitch
50mm= length of fastener
machine screws - special group of screws 3/8'' or less in diameter
to find the diameter of a machine screw - multiply the screw number by 0.013
add 0.060
Ex:
#6 machine screw
6 x 0.013 = 0.078
0.078 + 0.060 = 0.138''
, self tapping machine screw - is installed into a drilled hole slightly smaller than the major diameter of
the screw
find the tap needed for a drill - TDS= Nominal dia - pitch
lubrication does what? - reduces friction and increases life by reducing wear
sliding friction - contact spread over a large surface, pressure per sq in usually light
rolling friction - rolls over a surface, area of contact is quite small pressure load is high
fluid friction - two surfaces in contact, a film of oil is formed ,filling up the depressions and covering
the projections on both surfaces.
adheasion - forces cause unlike material to stick together
cohesion - cause molecules of like material to stick together
viscosity - the resistance to flow
choosing viscosity - depends on speed, load, temp, pressure, and environment
how is viscosity measured? - dynamic and kinematic
kinematic viscosity - affected by the density of the oil measured in centistokes
calcium soap grease - requires a small amount of water to stabilize. recommended for damp
conditions with low heat
sodium soap grease - soluble in water but has high temperature range. only used in dry and high
temp conditions
WITH 100% CORRECT ANSWERS
What does(3/4''-10 unci -2a x 1 1/2'' )stand for? - 3/4''= Nominal diameter
10 = Threads per inch
UNC = thread style (Unified national Course)
2= Class of fit
A= External thread (b= internal thread)
1 1/2''= length (depth of full threads in hole)
class of fit 1,2,3,4,5&6 - class 1 fit= maximum looseness in mating threads
class 2 fit= average fit little play in mating threads
class 3 fit= no looseness in mating threads.
class 4 fit= precision threads, usually cut and ground
class 5 and 6 fit= embellishments of class 4, but the most precise and accurate threads.
what does M8x1.25x50mm stand for? - M= Metric
8= nominal diameter in mm
1.25= the pitch
50mm= length of fastener
machine screws - special group of screws 3/8'' or less in diameter
to find the diameter of a machine screw - multiply the screw number by 0.013
add 0.060
Ex:
#6 machine screw
6 x 0.013 = 0.078
0.078 + 0.060 = 0.138''
, self tapping machine screw - is installed into a drilled hole slightly smaller than the major diameter of
the screw
find the tap needed for a drill - TDS= Nominal dia - pitch
lubrication does what? - reduces friction and increases life by reducing wear
sliding friction - contact spread over a large surface, pressure per sq in usually light
rolling friction - rolls over a surface, area of contact is quite small pressure load is high
fluid friction - two surfaces in contact, a film of oil is formed ,filling up the depressions and covering
the projections on both surfaces.
adheasion - forces cause unlike material to stick together
cohesion - cause molecules of like material to stick together
viscosity - the resistance to flow
choosing viscosity - depends on speed, load, temp, pressure, and environment
how is viscosity measured? - dynamic and kinematic
kinematic viscosity - affected by the density of the oil measured in centistokes
calcium soap grease - requires a small amount of water to stabilize. recommended for damp
conditions with low heat
sodium soap grease - soluble in water but has high temperature range. only used in dry and high
temp conditions
