Page 710 - Mastik®

General Metric ISO threads

The thread dimensions and profile accuracy are crucial for r XIFUIFS UIF UISFBE DBO USBOTNJU UIF GPSDFT GPS XIJDI UIF DPN
determining: ponents were dimensioned.
r 5PMFSBODFT BSF WFSZ TNBMM JO TDSFX NBOVGBDUVSJOH 5FSNT BOE
r XIFUIFS B DPBUJOH DBO TUJMM CF BQQMJFE UP UIF TDSFX UISFBE fitting systems are difficult to understand. To assist. the fol-
r XIFUIFS UIF QBSUT UP CF KPJOFE DBO CF TDSFXFE UPHFUIFS PO lowing illustrations explain dimensions and tolerances.
assembly without difficulty or the need for reworking.

Basic concept and nominal
Nut 60°
dimensions according to ISO 724
nominal size of thread

The dimension system for threads is based on the nominal di- Bolt
mensions for thread, pitch and minor diameter. major diameter D 2 pitch diameter D 1 minor diameter P pitch d 2 pitch diameter major diameter

D D d
Nut Bolt

Clearance fit on metric ISO threads
Nut
according to ISO 965
El
TD 2 2 2 T d 2
Screw and nut threads have different tolerance zone positions:
screw thread dimensions are situated at the nominal dimension TD 1 2 Td 2 2
and below, nut thread dimensions, at the nominal dimension and
above. es
2
This produces the necessary clearance and a defined range for major diameter max. major diameter min. pitch diameter max. pitch diameter min. minor diameter max. minor diameter min. pitch diameter min. pitch diameter max. major diameter min. major diameter max.
permissible plating thicknesses: a plated screw thread must Bolt
never exceed the nominal dimensions, while a plated nut thread
must never fall below them (see T.031).

Tolerance fields for commercial Tolerance quality Tolerance zone position
Diameter-dependent tolerances Pitch-dependent dimensions
screws and nuts for different tolerance for different tolerance
qualities can be found in zone positions can be found
ISO 965. in ISO 965.
according to ISO 965
6G
6H
Clearance G
The ISO 965 thread standard recommends tolerance fields before H
which give the desired clearance. For threads ≥ M1,4, the fol- 4 5 6 7 8 application of h bolt thread nut thread
lowing tolerance fields are standard! 6g protective coats g
6e f
Nut Bolt finish Larger number e
means greater
6H 6g bright, phosphated or for standard
tolerance.
electroplatings
Ø major Ø pitch Ø major Ø pitch
6G 6e bright (with large clearance) or for
very thick electroplatings
6g-ring gauges for plain screw threads Tolerance fields of screw and nut threads
6h-ring gauges for plated screws