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EXPLANATION OF TERMS FOR MAINTENANCE STANDARD
EXPLANATION OF TERMS FOR MAINTENANCE STANDARD
The maintenance standard section shows the judgment criteria whether the equipment or parts should be re-
placed or can be reused when the machine is disassembled for the maintenance. The following terms are the
descriptions of the judgment criteria.
Standard dimension and tolerance
•
The finished dimension of a part is slightly different from one to another actually.
•
A standard dimension of a finished part is set, and an allowable difference from that dimension is set for the
part.
•
The dimension set as the standard is called the standard dimension and the allowable range of difference
from this standard dimension is called "tolerance".
•
An indication example of a standard dimension and tolerance is shown in the following table.
(The standard dimension is entered on the left side and the tolerance is entered with a positive or negative
symbol on the right side)
Example:
Standard dimension
•
The tolerance may be indicated in the text and a table as "standard dimension (upper limit of tolerance/
lower limit of tolerance)."
Example) 120 (-0.022/ -0.126)
•
Usually, the dimension of a hole and the dimension of the shaft to be inserted into that hole are indicated by
the same standard dimension and different tolerances of the hole and shaft. The tightness of fit is deter-
mined by the tolerance.
•
A dimension indication example of a shaft and hole is shown in the following table.
(The standard dimension is entered on the left side and the tolerance of the shaft is entered with a positive
or negative symbol at the center and that of the hole on the right side)
Standard dimension
60
00-78
120
Tolerance
Shaft
-0.030
-0.076
00 INDEX AND FOREWORD
Tolerance
-0.022
-0.126
Hole
+0.046
0
PC210LCI-11
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