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GB/T 3103 consists of the following parts under the general title Tolerances for fasteners:
——GB/T 3103.1 Tolerances for fasteners—Bolts, screws, studs and nuts;
——GB/T 3103.2 Tolerances for fasteners—Bolts, screws and nuts for fine mechanics;
——GB/T 3103.3 Tolerances for fasteners—Plain washers;
——GB/T 3103.4 Tolerances for fasteners—Bolt/nut assemblies for service temperatures from -200°C~+700°C
This is Part 3 of GB/T 3103.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 3103.3-2000 Tolerances for fasteners—Plain washers.
The following main technical changes have been made with respect to GB/T 3103.3-2000:
——the scope is modified (see Clause 1);
——the normative references are updated (see Clause 2);
——a new Clause 3 "Symbols" is added (see Clause 3);
——new product grade F is included (see Clauses 1 and 4);
——tolerances for chamfers are included (see Clause 4);
——standard tolerance grades IT11 and IT14 are included and IT16 is deleted (see Table A.1);
——limit deviations for tolerance classes h13 and H12 respectively are included (see Tables A.2 and A.3).
This part has been redrafted and modified in relation to ISO 4759-3:2016 Tolerances for fasteners—Part 3: Washers for bolts, screws and nuts—Product grades A, C and F.
The technical deviations of this part from ISO 4759-3:2016 and their justifications are as follows:
——In the normative references, Chinese standards are used instead of international standards (see Clause 2), so as to meet the basic standards of fasteners in China.
The following editorial changes have also been made in this part:
——The standard name is modified.
This part was proposed by China Machinery Industry Federation.
This part is under the jurisdiction of the National Technical Committee on Fasteners of Standardization Administration of China (SAC/TC85).
The National Technical Committee on Fasteners of Standardization Administration of China is in charge of the interpretation of this part.
The previous editions of this part are as follows:
——GB/T 3103.3-1982, GB/T 3103.3-2000.
Tolerances for fasteners—Plain washers
1 Scope
This part of GB/T 3103 specifies tolerances for plain washers of product grades A, C and F with nominal diameters of 1 mm to 150 mm inclusive, designed to be used in bolted joints in combination with bolts, screws, studs and nuts.
This part is applicable to non-captive and captive plain washers, and to standard and non-standard plain washers.
This part may be applied to non-plain washers, however, it does not include all the tolerances related to these washers.
This part is not applicable to tapered washers.
Washers of product grades F and A are intended to be used with bolts, screws, studs and nuts of product grades A and B; washers of product grade C are intended to be used with bolts, screws, studs and nuts of product grade C.
Note: The product grade refers to a specific tolerance range related to dimensional and geometrical characteristics (product grade F for fine tolerances, product grade A for precise tolerances, product grade C for large tolerances).
Annex A presents the standard tolerances and the limit deviations for shafts and holes taken from GB/T 1800.1 and GB/T 1800.2.
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 1182 Geometrical product specifications (GPS)—Geometrical tolerancing—Tolerances of form, orientation, location and run-out (GB/T 1182-2018, ISO 1101:2017, IDT)
GB/T 16671 Geometrical product specifications (GPS)—Geometrical tolerancing—Maximum material requirement (MMR), least material requirement (LMR) and reciprocity requirement (RPR) (GB/T 16671-2018, ISO2692:2014, MOD)
3 Symbols
For the purposes of this document, the following symbols apply.
c1 height of the inner chamfer, mm
c2 height of the outer chamfer, mm
d1 hole diameter, mm
d2 shaft diameter, mm
e1 radial difference between the hole diameter (area subject to shearing) and the end of the brittle fracture on the bearing side of the washer
e2 radial difference between the outside diameter (area subject to shearing) and the end of the brittle fracture on the bearing side of the washer
heff effective height of the washer, mm
t nominal thickness of the washer, mm
teff effective thickness of the washer, mm
t1 part of the hole diameter within the tolerance specified for d1
t2 part of the outside diameter within the tolerance specified for d2
y coaxiality, mm
z flatness (deflection), mm
4 Tolerances
The tolerances for washers of product grades A, C and F are specified in Table 1.
Unless otherwise specified, the tolerances specified in this part apply to washers prior to surface treatment.
Deviations from the tolerances specified in this part are permitted in product standards only for valid technical reasons. In cases where there is a difference between the tolerance requirements in this part and the product standard, the latter takes precedence.
The tolerances of form and position are specified and indicated according to GB/T 1182 and GB/T 16671.
Foreword i
1 Scope
2 Normative references
3 Symbols
4 Tolerances
Annex A (Informative) Tolerances
Bibliography
