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00 Index and foreword
Explanation of terms for maintenance standard
The maintenance standard values necessary for judgment of products and parts are described by the follow-
ing terms.
1.
Standard size and tolerance
To be accurate, the finishing size of parts
q
is a little different from one to another.
To specify a finishing size of a part, a tem-
q
porary standard size is set and an allow-
able difference from that size is indicated.
The above size set temporarily is called
q
the "standard size" and the range of differ-
ence from the standard size is called the
"tolerance".
The tolerance with the symbols of + or – is
q
indicated on the right side of the standard
size.
Example:
Standard size
120
a The tolerance may be indicated in the text
and a table as [standard size (upper limit
of tolerance/lower limit of tolerance)].
Example) 120 (–0.022/–0.126)
Usually, the size of a hole and the size of
q
the shaft to be fitted to that hole are indi-
cated by the same standard size and dif-
ferent tolerances of the hole and shaft.
The tightness of fit is decided by the toler-
ance.
Indication of size of rotating shaft and hole
q
and relationship drawing of them
Example:
Standard size
60
PC160LC-7E0
Tolerance
–0.022
–0.126
Tolerance
Shaft
Hole
–0.030
+0.046
–0.076
+0
SEN01895-02
1
9
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