runout means the radial play of the rotor or shaft.
it must be in between 0.02 to 0.03 for large turbine rotors.
First of all u have to conform how many areas u want to
take run out. On that basis u put the dial guages on that
flanges or bearing journals.
setting of dial guage is in such a way that it must be sit
on the parting plane and the dial point must be touch that
corresponding flange or bearing journal.
press the dial upto 5mm pressure. and set the dial into
zero and that is the reference point i.e. zero point
rotate the rotor and take the readings for every 90 degrees
At zero degree what is the reading, not down
at 90 degree reading, 180 deg reading, 270 deg reading and
finally again 0 degree reading.
Out of these check where is the max reading u observed.
Whether the max reading is within the limit or not u check
This total process i am telling is regarding turbine rotor
But whatever it may be the process is same but the limits
Runout is a composite control which control form,
orientation and location. Runout is often used to control
coaxiality of diameters.
The conditions for Runout are
-> Datum reference is a must.
-> Geometric tolerance must be specified at RFS.
-> It must be applied to Cylinderical Feature Of Size(FOS).
Circular / Radial Run-out:
Circular run-out or simply run-out is an error in the form
of mechanical components like cylindrical surfaces, shafts,
rotors etc. By definition, run-out refers to error of
roundness or form measured along a specified sectional plane
from the axis.
Mostly, this feature is measured using dial indicator while
the part or component is being clamped in the headstock of
lathe machine (for example). When measured using dial
indicator, two extreme values are obtained for a specified
sectional plane. Mathematically, the difference of these
extreme values is circular run-out.
Axial / Total Run-out:
When circular or radial run-out is measured along the axis
of rotation or simply axis of the part or component, then it
is called Axial or total run-out. To measure this, selection
of planes is necessary. For long components, it is advisable
to separate sectional planes equidistant almost 100 mm.
Mathematically, axial run-out is calculated as follows: -
first measure circular run-out along each sectional planes,
then look for extreme values i.e. maximum and minimum values
among all circular run-out readings so obtained using dial
indicator. The difference of extreme values along the axis
is called axial or total run-out.
suppose, there are 4 sectional planes selected for a shaft.
Readings of circular run-out obtained using dial indicators are:
Section Plane -1: Max:1.5, Min: 0.8
Section Plane -2: Max:1.6, Min: 0.7
Section Plane -3: Max:1.3, Min: 0.9
Section Plane -4: Max:1.45, Min:0.11
Maximum value among above values: 1.6
Minimum value among above values: 0.7
Axial Run-out= 1.6-0.7=0.9
Run out is flash like stucture .But it is diferent from flash
flash occure during improper ramming of sand,but in run out
there is ramming is done properly and deffect comes out
which flash like structure due to hydrostatic preassure of
molten metal and insufficeant weight of cope .to avoide it
ther must kept some extra weight over cope .
Runout is also a metal casting defect. It is defined as a
leakage of molten metal from a cracked or broken shell, which
results in finning and/or loss of metal. The resulting
casting may contain non fill, short pour and/or shrink defects.