GB/T 35480-2017 in English

《GB/T 35480-2017紧固件 螺栓、螺钉和螺柱预涂微胶囊型粘合层技术条件》由TC85（全国紧固件标准化技术委员会）归口，主管部门为中国机械工业联合会。

GB/T 35480-2017 Fastener - Steel bolts, screws and studs with microencapsulated adhesive pre-coating technical specification

1 Scope

This standard specifies the terms, pre-coating dimensions, performance requirements and test methods for pre-coating microcapsulated adhesive (hereinafter referred to as "adhesive coating") on steel bolts, screws and studs (hereinafter referred to as "externally threaded fasteners").

This standard is applicable to threads conforming to GB/T 193, with thread specifications of M3 ~ M39, coarse threads and nominal diameter d = 8 mm ~ 39 mm or fine threads.

This standard is applicable to externally threaded fasteners made of carbon steel or alloy steel in accordance with GB/T 3098.1 and externally threaded fasteners made of stainless steel in accordance with GB/T 3098.6. Cross recessed screws below Grade 8.8, hexalobular socket pan head screws and screws with reduced bearing capacity may refer to this standard.

For lubricated surfaces, Annex A gives references for system performance test at high temperature. Annex B gives the pre-coating products and the references of the applicable operating temperature range.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 97.1 Plain washers - Product grade A
GB/T 1237 Designation system for fasteners
GB/T 5277 Fasteners - Clearance holes for bolts and screws
GB/T 5783 Hexagon head bolts - Full thread
GB/T 6170 Hexagon nuts, style 1
GB/T 16823.3 Fasteners - Torque/clamp force testing

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1
microencapsulated adhesive coating
coating which is formed by mixing a microencapsulated initiator or hardener with an adhesive and then applying on threads of an externally threaded fastener; when the externally threaded fastener is tightened, the pre-coated adhesive solidifies and bonds the engaging part of the externally threaded fastener, thus improving the anti-loosening performance of the externally threaded fastener

3.2
screw-in torque
Tin
torque measured when an externally threaded fastener is screwed into a nut specimen

3.3
tightening torque
TA
torque applied on a nut or an externally threaded fastener head in tightening

3.4
breakaway or untightening torque
TLB or TL
torque (TLB) measured at the moment when the externally threaded fastener and the test nut loosen for the connection of the externally threaded fastener with or without pre-tightening force with an adhesive coating; torque (TL) measured at the moment when the externally threaded fastener and the test nut loosen for the connection of the externally threaded fastener with pre-tightening force without the adhesive coating

3.5
loosening torque
Tout
maximum torque measured by means of loosening the externally threaded fastener until the axial load is removed, and continuing to loosen until out of engaging area of the adhesive coating

3.6
suitability test
performance test of different types of adhesive coatings conducted according to the friction coefficient of threads, operating temperature range, corrosion resistance and long-term heat resistance of externally threaded fasteners and nuts under test

Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Pre-coating dimensions
5 Performance requirements
6 Test methods
7 Pre-coating marking
8 Storage requirements
Annex A (Informative) Supplementary explanation on systematic test
Annex B (Informative) Pre-coating microencapsulated adhesive coating for externally threaded fasteners (locking adhesive)
Bibliography