ISO System of Limits and Fits
ISOTOLTM Computer Tolerance Software ISBN 0-9744477-1-4
Preferred metric sizes, fits, and tolerance zones for holes (H11, H9, H8, H7) and shafts (h11, h9, h7, h6) are covered in the Preferred Metric Limits and Fits, ANSI B4.2 1978, standard. The purpose of this standard is to help American manufacturing to cut costs in terms of engineering time, tooling, material stock, gages, etc. The material in the ISOTOLTM* and METRIC STANDARDS for Worldwide Manufacturing are based on the above standard. You may also want to introduce the ISO System of Limits and Fits (ISOTOLTM) in your business, which has been successfully used around the world for 70 years and saved billions of dollars in manufacturing and engineering. For nearly two years a free online version of the ISOTOLTM has been available. The online version was not intended to help design a metric fit, but to interpret an existing metric fit and convert it to inches. New online versions will be available later this year.
NOTE*: The online version of the ISOTOLTM will not be available until later this year. ISO System of Limits and Fits coded limits may be calculaded from tables in the METRIC STANDARDS for Worldwide Manufacturing electronic or hardcover editions or from the tables in Chapter 6. You may want to purchase the first edition of the software stored on an ISOTOLTM CD.
The ISO System of Limits and Fits is a highly
successful tolerance system to help cut costs in manufacturing and
engineering. Germany has taken the lead in this area, and it
has helped cut cost of engineering time, material stock (see
h11, h9, h7, h6), cutting tools and gages. GO/NOGO gages
held to these tolerances are readily available in Germany and most
other countries. The American National Standard ASME B4.2
cover the preferred metric sizes, preferred tolerance zones and the
ten preferred hole or shaft basis fits used throughout the world.
You have had free access to the online version of the
software for nearly two years.
This free service has ended, and please
me for future options. The site
still provides free interpretations of all tolerance zones with
metric limit dimensions for sizes in the ISO system. You may
want to use the ISO system here, and it is a powerful
; Simply click on one of the ten proven fits . If
you decide to use a different hole or shaft tolerance, you can
increase or reduce the clearance by just a click on one of the 150
other tolerance zones. Each time the new fit condition
is instantly displayed. You can modify the fit,
and still specify one of the first choice tolerance zones for holes
(H11, H9, H8, H7)
(h11, h9, h7, h6 ) which produce the largest
cost reductions in gages, material stock and tooling.
The ASME B32.100-2005 material standard and other
standards for cold finished steel rod material specify
the four (4) preferred shaft tolerances h11, h9, h7, and h6 in all
the largest industrial countries of the world.
Preferred Metric Sizes ; Click on first, second or third choice metric size or enter your own special size up to 500 mm.
You may also click on a preferred inch size or enter a special size followed by the inch (") symbol.
Output ; Instant display of limit dimensions for hole, shaft and fit.
For example; 25H11/c11 (hole 25.130/25.000; shaft 24.890/24.760; fit 0.370/0.110)
Press Copy in order to transfer the above line to drawing or specification.
This page provides a description of the ISO System of Limits and
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