OPERATOR’S MANUAL
31
SECTION 1
GLOSSARY OF TERMS
Cp
This is a capability index which shows the process capability
potential but takes no account of how centred the process
is. This is used for capability studies and Cp may range in
value from 0 to infinity. A large value indicates greater
potential capability and a value of 1.33 or greater is desirable.
Max - Min
Cp =
6 s
(Max and Min are limit values)
CpK
This is an index which indicates whether the process will
produce units within the tolerance limits. If the process is
centred on the nominal value then CpK will have a value
equal to Cp. For values of CpK between 0 and 1 then some
of the 6 sigma spread will fall outside tolerance limits but for
values greater then 1 these will all be within tolerance. A
negative value of CpK indicates that the process mean is
outside tolerance limits. A value of 1.33 or greater is
desirable.
(Max - x-)
(x- - Min)
CpK = lesser of
3 s
or
3 s
(Max and Min are limit values)
CAM
This is an alternative capability index requiring a minimum
of 30 readings to be taken. In this implementation, 5 sub-
groups of 6 samples are used for each calculation. The CAM
calculation uses the following formula:
Max - Min x Cam Factor *
6 x Average Sample Value
* CAM Factor is taken from a table (in the case of 5 x 6
samples = 1.910)
High Output
Torque transducer with no coding links but internal pre-
amplifierTransducer (H/O) giving an output signal level of
typically 1 or 2 volts.
Horizontal
Collection of data by round, taking one reading for each
sampling Job in turn.
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.
Job
Specification of one particular torque value to be collected.
Each Job has a name of up to 14 characters, 8 if
downloaded from a PC. TorqueStar Opta can store up to
275 different Jobs at any one time.
Master Round
A sequence of up to five rounds. It is used to allow a collection
sequence, which is part vertical, part horizontal.
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.
No. of Sub Groups
Number used to allocate memory space in TorqueStar Opta,
for a particular Job. May be set in the range of 1 to 50.
Round
A sequence of Jobs to be collected either horizontally or
vertically. Each round has a name of up to 14 characters, 8
if downloaded from the PC.
Sample
Individual torque reading.
