Ingersoll Rand Expert Torque Analyzer Manual Del Usuario página 16

EN
d5
A divisor of R used to estimate the process standard deviation or Within-Subgroup Variation, σ
group size of 5 is based on the following equation:
[(1.645 x 0.864)]
d5 = 2.326 –
√(number of subgroups)
Industry Standard Transducer (I/S)
Type of transducer, with no pre-amplifier or coding links, but with the exact rated torque, marked on the body.
Lower Specification Limit, LSL
The lower engineering specification limit.
Max Torque Value
Upper tolerance level of any reading. This can equal but not exceed the torque rating of the transducer to be used.
Min Torque Value
Lower tolerance level of any reading.
R
The average range of a series of subgroups of constant size.
Sample
Individual torque reading.
Standard Deviation , σ
Is a measure of the variation of the samples of a statistical group.
Subgroup
Grouping of 5 samples, or readings, to enable analysis, with an allowable range of 1-40 subgroups.
Threshold Torque Value
Level of torque in which a signal must rise above and then fall below to be considered a valid torque cycle. This may be set in the range of 1%
of rated span up to the Min Torque Value.
Total Process Variation, σ
P
The estimate of the standard deviation of a process using the sample standard deviation of a set of individuals about the average of the set. It
is given by the equation:
σ =
P
Units of Measure
The torque units of measurement. For instance, it is possible to read a transducer calibrated in Nm and convert internally to display and store in
any of the other torque units.
Upper Specification Limit, USL
The upper engineering specification limit.
TRD, TSD or UTA Transducers
Family of torque transducers which the EXTA can automatically identify by coding links.
Within-Subgroup Variation, σ
The estimate of the standard deviation of a stable process using the average range of subgrouped samples taken from the process, usually
within the context of control charts, where the d2 factor is used. It is given by the equation:
= R
σ
C d2
Within-Subgroup Variation σ
The estimate of the standard deviation of a stable process using the average range of subgrouped samples taken from the process, usually
within the context of control charts, where the d5 factor is used. It is given by the equation:
σ = (4/3)*(R/d5)
CAM
X
The average of values of a set of individuals or of a subgroup.
X
The average of subgroup values.
EN-15
C
CAM
, for CAM & CMK. The value of d5 for a sub-
CAM
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