This part is one of the national standard series on “wire thread inserts”, which consists of:
a) GB/T 24425.1-2009 General type wire thread inserts;
b) GB/T 24425.2-2009 General type wire thread inserts for blind hole;
c) GB/T 24425.3-2009 Prevailing torque type wire thread inserts;
d) GB/T 24425.4-2009 Prevailing torque type wire thread inserts for blind hole;
e) GB/T 24425.5-2009 Internal thread for wire thread inserts;
f) GB/T 24425.6-2009 Specification for wire thread inserts.
This is Part 3 of GB/T 24425.
Prevailing torque type wire thread inserts
1 Scope
This part of GB/T 24425 specifies prevailing torque type wire thread inserts with symmetrical profile with nominal thread diameter of 3mm~39mm and pitch of 0.5mm~4mm.
As for the internal thread formed by screwing the wire thread inserts specified in this part into the internal thread for 5H specified in GB/T 24425.5, the tolerance zone is 5H (GB/T 197).
The wire thread inserts specified in this part is applicable to improving the strength of screw holes in material body made of low-strength materials (such as aluminum alloy, magnesium alloy, copper alloy, cast iron and nonmetal), improving the fatigue strength of screws, improving the locking performance and repairing damaged screw holes.
Note: The nominal thread diameter and specification of wire thread inserts used in this part refer to the nominal diameter and specification of internal thread formed by screwing the wire thread inserts into the internal thread specified in GB/T 24425.5.
2 Normative references
The following documents contain provisions which, through reference in this part of GB/T 24425, constitute provisions of this part. For dated references, subsequent amendments (excluding corrections) to, or revisions of, any of these publications do not apply to this part. However, parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 197 General purpose metric screw threads - Tolerances (GB/T 197-2003, ISO 965-1: 1998, ISO general purpose metric screw threads - Tolerances - Part 1: Principles basic data, MOD)
GB/T 1237 Designation system for fasteners (GB/T 1237-2000, eqv ISO 8991: 1986)
GB/T 24425.5 Internal thread for wire thread insert
GB/T 24425.6 Specification for wire thread inserts
3 Dimensions
3.1 The type and dimension of wire thread inserts in free state shall be as shown in Figure 1 and specified in Table 1 and Table 2.
Foreword i
1 Scope
2 Normative references
3 Dimensions
4 Locking ring
5 Technical specifications
6 Marking
Annex A (Information) Nominal length, number of turns in free state and length after mounting of wire thread inserts
