This standard specifies the dimensional tolerance levels and tolerance values ​​for molded, extruded and calendered compact rubber products, and also specifies the corresponding test methods required to determine compliance with this standard. The tolerances specified in this standard apply to vulcanized rubber and may also apply to products made of thermoplastic rubber. This standard does not apply to calendered composite products such as precision annular seals or adhesive tapes, or products coated with rubber coatings by coating or sticking. GB/T 3672.1-2002 Tolerances for rubber products Part 1: Dimensional tolerances GB/T3672.1-2002 Standard download decompression password: www.bzxz.net

GB/3672.1-2002
This standard is equivalent to adopting 1S03302-1:1996 "Tolerances of rubber products - Part: Dimensional tolerances" to revise GB/T3672-1992.
This standard is the second revision of GB/T3672-~·1992 "Dimensional tolerances of molded, extruded and calendered solid rubber products". Compared with GB/T3672~-1992, the revised content has the following changes: - The name is changed from the original "Dimensional tolerances of molded, extruded and calendered solid rubber products" to the current name. ... The division of the nominal size ranges in Tables 1, 4 and 9 has changed. The tolerances of certain levels within certain nominal size ranges in Tables 1, 2, 3, 4, 7 and 8 have also been modified according to ISO3302 to the original national standard.
This standard and GB/T3672.2-2002 "Tolerances for Rubber Products Part 2: Geometric Tolerances" together constitute the tolerance standards for rubber products.
This standard replaces GB/T3672-1992 from the date of implementation. This standard was proposed by the National Petroleum and Chemical Industry. This standard is under the jurisdiction of the Sealing Products Sub-Technical Committee of the National Technical Committee for Rubber and Rubber Products Standardization. This standard was drafted by the Northwest Rubber and Plastic Research and Design Institute, and the participating units include Guizhou Dazhong Rubber Co., Ltd. and Shanghai Rubber Products. The main contributors to this standard are Gao Jingru, Yuan Li, Wang Guixian, and Cai Ming. 1
GB/T 3672. 1—2002
ISO Foreword
The International Organization for Standardization (ISO) is a worldwide organization of national standardization bodies (ISO members). The work of formulating international standards is usually carried out by ISO technical committees. Any member group interested in a project for which a technical committee has been established has the right to participate in the committee. Governmental and non-governmental organizations in liaison with ISO also have the right to take part in the work. ISO maintains close liaison with the International Electrotechnical Organization (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires participation by at least 75 % of the members.
International Standard ISO 3302-1 Prepared by Technical Committee ISO/TC 45 Rubber and rubber products, Subcommittee SC 4 Miscellaneous Products This edition 1 ISO 3302-1 cancels and replaces ISO 3302:1990 "Dimensional tolerances for rubber products", which contains technical revisions, in particular Table 1 (Tolerances for moulded products).
ISO 3302-1 consists of the following parts under the general title "Tolerances for rubber products": Part 1: Dimensional tolerances
Part 2: Geometrical tolerances
GB/T 3672.1.-2002
Rubber products are susceptible to dimensional changes after processing and vulcanization. This may be due to various factors such as shrinkage during moulding or relaxation during extrusion expansion.
These variations should be determined and considered when designing components such as moulds and dies to manufacture a particular product. The higher tolerance levels listed in this specification should only be used when required by the final application and should be limited to dimensions that are considered critical. The higher the precision of the group adopted, the stricter the control that must be exercised during the manufacturing process, and the higher the surface cost. The product requires some special properties, which may not always be provided by using a rubber compound that can be moulded with close tolerances. In this case, negotiation should be reached between the parties concerned. Generally speaking, low hardness vulcanizates (i.e. vulcanizates with a hardness of less than 50 IRHD, see ISO 48) require larger tolerances than high hardness vulcanizates. 13
1 Scope
National Standard of the People's Republic of China
Tolerances of rubber products
Part 1: Dimensional tolerances
Rubber---Tolerances of productsPart 1: Dimensional tolerancesGB/T 3672. 1-- 2002
idt ISO 3302-1: 1996
Replaces GB/T3672---1992
This standard specifies the dimensional tolerance classes and tolerance values ​​for compact rubber products that are molded, extruded and calendered, and also specifies the corresponding test methods required to determine compliance with this standard.
The tolerances specified in this standard apply to vulcanized rubber and may also apply to products made of thermoplastic rubber. This standard does not apply to calendered composite products such as precision annular seals or adhesive tapes, or products coated with rubber coatings by coating or sticking.
2 Reference Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T 321-1980 Priority numbers and priority number systems GB/T 2941-1991 Standard temperature, humidity and time for environmental conditioning and testing of rubber specimens (eqv ISO 471: 1995) GB/T 5723-1993 Determination of dimensions of test specimens and products for testing vulcanized rubber or thermoplastic rubber (eqv ISO 4648: 1991)
GB/T 6031--1998
Determination of hardness of vulcanized rubber or thermoplastic rubber (10~~100IRHD) (idt ISO 48: 1994) ISO 2230: 1973 Guide to storage of vulcanized rubber) 3 Measurement of dimensions
3.1 General
For solid products, the measurement of dimensions should be carried out 16 hours after vulcanization. In case of dispute, this minimum time may be extended to 72 hours. The measurement shall be completed within three months after the date of shipment to the buyer or before the product is put into use (whichever is shorter), and the measurement shall be carried out at standard temperature after environmental adjustment (see GB/T2941). Care shall be taken to ensure that the product is not subjected to harmful storage conditions (see ISO2230) and that the product does not deform during the measurement. 3.2 Test Instruments
3.2.1 Measurements shall be made using one or more of the following types of instruments, depending on the circumstances. 3.2.1.1 Solid products may be measured using a dial micrometer gauge. The micrometer gauge foot shall be applied to rubber with a hardness equal to or greater than 35IRHD. 1) The original text of this standard can be found at the Standards Library of the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, and is under the jurisdiction of the National Technical Committee for Standardization of Rubber and Rubber Products. Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on May 29, 2002 14
2002-12-01 implementation
GB/T 3672.1 ---2002
22kPa ± 5kPa pressure, while for rubber with a hardness less than 35IRHD, a pressure of 10kPa ± 2kPa should be applied (see GB/T5723 and GB/T 6031).
3.2.1.2 Suitable optical measuring instruments.
3.2.1.3 Fixed gauges with upper and lower limits corresponding to the dimensions to be measured. 3.2.1.4 Other measuring instruments, including tape measures (with or without vernier), vernier calipers and vernier scales. 3.2.2 The measuring errors of all instruments shall be within the specified tolerance range. 3.2.3 The same measuring instrument shall be used for all measurements intended for comparison. 4 Tolerances
For the purpose of this standard, nominal dimensions and tolerances are based on the R5 and R10 series priority numbers respectively (see GI3321). The dimensions of certain parameters of individual products may not all require the same level of tolerance. Different levels of tolerance may be used for different parameter dimensions of products on the same drawing. When the required level of tolerance is not indicated on the drawing, the maximum tolerance listed in the relevant table shall be used. 浅
1 Tolerances specified in this standard expressed as equal positive and negative values ​​(such as ±0.35) may also be expressed as unequal positive and negative values ​​as long as the difference between the two values ​​remains unchanged. For example, ±0.35 can also be expressed as ±8: or +87 or -8.7, etc. 2 For vulcanizates with low hardness and high tensile strength (such as vulcanizates of natural rubber), it is necessary to give special consideration to the tolerances. 5 Moulded products
5.1 General
The dimensional tolerances stated in this standard are wider than those used in some other engineering practices. This is to take into account the following: a) All rubbers shrink to some extent when cooled after moulding, so this should be taken into account in the mould design. The amount of shrinkage depends on the type of rubber and compound used, and the shrinkage of the same compound also varies from batch to batch. Products made from some silicone rubbers, fluororubbers and other special elastomers shrink so much that it is difficult to achieve M1 and M2 grades using these rubbers (see 5.2) Tolerance requirements.
b) Non-rubber parts bonded to the rubber affect shrinkage and thus also affect the practical tolerances. c) The molds should be made in different ways depending on the type of product and the required accuracy. Usually the accuracy of the product will not be higher than the mold, and the higher the accuracy required, the more expensive the mold and other maintenance costs will be. d) For products with large cross-sectional variations, caution should be exercised when using standard tolerances. 5.2 Classification
This section specifies four tolerance classes for fixed dimensions and molded dimensions of solid molded products (see 5.3), namely: a) Class M1, suitable for precision molded products. This type of molded product requires precision molds, fewer cavities per mold, close control of the rubber, etc., and is therefore expensive. In order to avoid deformation of the rubber by the measuring instrument, an optical comparator or other similar measuring instrument is required. This type of part requires expensive control and inspection procedures. b) Class M2. Suitable for high-quality molded products, including many of the close controls required for M1. c) Class M3. Suitable for good quality molded products. d) M4 grade, suitable for molded products with loose dimensional control. 5.3 Fixed dimensions and molded dimensions
When molding a rubber product, more rubber is used than is needed to fill the mold cavity, and this excess rubber overflows. This overflow often prevents the mold parts from closing completely, thus affecting the dimensions of the finished product. Note: For products molded by transfer or injection methods, all dimensions can be considered fixed dimensions. Two sets of tolerances F and ( are given, and their definitions are as follows: 15
GB/T3672.1—2002
5.3.1 Fixed dimension (F): Dimension that is not affected by deformation such as flash thickness or lateral displacement of different parts of the mold (upper, lower parts or mold core). See dimensions 11, 12, 13 in Figure 1. 5.3.2 Closed mold dimension (C): Dimension that is affected by flash thickness or lateral displacement of different parts of the mold. See dimensions dl, d2, d3 and h in Figure 1.
Note: The tolerances of dimensions F and C can only be determined when they are not related to each other. Upper mold
Pressure direction| |tt||Molded parts
Figure 1 Compression mold and molded parts (schematic diagram) 5.4 Tolerances
The tolerances adopted should be selected from the tolerance grades described in 5.2 through consultation between the relevant parties. The standard tolerances are listed in Table 1. The fixed size tolerance (F) is related to the size of each dimension, while all mold size tolerances (C) are determined according to the largest mold size h (see Figure 1). Table 1 Tolerances of molded products
Nominal dimensions
Up to and including
mm (unless otherwise specified)
6 Extruded products
6.1 General
GB/T 3672. 1-- 2002
Extruded rubber products require greater manufacturing tolerances than molded products because the rubber undergoes expansion during extrusion and, in turn, generally shrinks and deforms during subsequent vulcanization.
Deformation can be reduced by the use of supports during vulcanization. The type of support will depend on the cross-section of the product and the degree of control required. These conditions determine the tolerance class that is appropriate for a given dimension. For some extruded products of synthetic rubber, it is not possible to achieve Class E1 tolerances directly. 6.2 Classification
This section specifies 11 tolerance classes for compacted rubber extruded products over specific ranges of dimensions, namely: a) Three tolerance classes for nominal cross-sectional dimensions of unsupported extruded products: E1 high quality class;
E2 good quality class;
F3 lax dimensional control class.
b) Three tolerance levels for nominal cross-sectional dimensions of core-supported extrusions: EN1 precision;
EN2 high quality;
FN3 good quality.
() Two tolerance levels (EG) for the outer dimensions (nominal outer diameter) of polished extrusions (pure rubber hoses) and two tolerance levels for the wall thickness of such extrusions (EW):
EG1 and EW1 precision;
EG2 and EW2
good quality:
d) Three tolerance levels for the cut length of extrusions and three tolerance levels for the thickness of cut parts of extrusions: L1 and EC1 precision;
1.2 and EC2
good quality;
non-strict dimensional control.
L3 and EC3
6.3 Tolerances
6.3.1 General
The tolerances to be used shall be selected from the tolerance classes given in 6.2 by agreement between the parties concerned. Standard tolerances are given in Tables 2 to 7.
On any extruded cross-section, the dimensions of the cross-section can be controlled by determining the dimensional tolerances of only two of the three variables (i.e., inside dimension, outside dimension and wall thickness).
6.3.2 Unsupported Extrusions
The dimensional tolerances of unsupported extrusions are given in Table 2. Hollow extrusions or extrusions of complex cross-section may collapse to some extent during vulcanization. Such collapse may be limited or prevented by enclosing such extrusions in a core or mold. The permissible deformation of the cross-section shall be specified by the purchaser. 6.3.3 Core-supported extrusions
Vulcanization of hollow extrusions can be carried out on a mandrel to obtain a closer inside dimension tolerance than unsupported. This method is suitable for pure rubber tubes that are subsequently used to cut seals or gaskets. Such products usually shrink when they are removed from the core mold, so the final specifications of the core-supported product size are smaller than the core mold specifications. However, if the positive tolerance of the core mold exceeds the amount of shrinkage of the extruded product, the product size may be larger. In this case, both positive and negative tolerances should be used. The inside dimension tolerances of heart-supported extrusions are listed in Table 3. Positive tolerances can be used for any tolerance of the core mold, but it is not allowed to change the inside dimension tolerance. The negative tolerance specified in Table 3 should not be increased. 17
GB/T3672.1—2002
All other dimensional tolerances shall comply with those specified in Table 2. 6.3.4 Extrusions with polished surfaces
6.3.4.1 The tolerances for the outside dimensions (usually the outside diameter) of extrusions with polished surfaces (usually pure hoses) are given in Table 4. NOTE: These tolerances also apply to seals cut from hoses. 6.3.4.2 The tolerances for the wall thickness of extrusions with polished surfaces (usually pure hoses) are given in Table 5. 6.3.5 Cut long sections
The length tolerances of cut sections of extrusions are given in Table 6. 6.3.6 Cut parts
The thickness tolerances of cut parts (e.g. rings, washers, discs) of extrusions are given in Table 7. NOTE: Only parts cut on a lathe can achieve tolerance levels EC1 and EC2. 2 Tolerances on cross-sectional dimensions of unsupported extruded products Table 2
Nominal dimensions
Up to and including
Table 4 Tolerances on dimensions of extruded products with polished surfaces mm (unless otherwise specified)
Nominal dimensions
Up to and including
EG1 grade
EG2 grade
Table 3 Tolerances on internal dimensions of extruded products with core support mm (unless otherwise specified)
Nominal dimensionswwW.bzxz.Net
Up to and including
ENI grade
EN2 grade
EN3 grade
5 Tolerances on wall thickness of extruded products with polished surfaces
Nominal thickness
Up to and including
EW1 grade
EW2 grade
GB/T 3672.1—2002
Table 6 Tolerances on length of cut sections of extruded products
mm (unless otherwise specified)
Nominal length
Up to and including
7 Calendered rubber sheets
Table 7 Tolerances on thickness of cut parts of extruded products
Nominal thickness
Up to and including
EC1 grade
EC2 grade
EC3 grade
7.1 General
The nominal size range and tolerance limits for calendered rubber sheets are similar to those for extruded products, taking into account the expansion of the rubber when it passes through the calender rollers and the deformation before and during vulcanization. The tolerances selected are also related to the surface finish of the rubber sheet. The thickness tolerance required for rubber sheets with cloth-grained surfaces is larger than that for smooth or calendered rubber sheets.
7.2 Classification
This section specifies six tolerance levels for compact calendered rubber sheets according to specific ranges of dimensions, namely: a) six tolerance levels for nominal thickness:
ST1 precision grade,
ST2 high quality grade;
ST3 good quality grade.
b) three tolerance levels for nominal width:
SW1 high quality grade;
SW2 good quality grade;
SW3 non-strict dimensional requirements grade.
7.3 Tolerances
The tolerances to be adopted shall be selected from the tolerance levels described in 7.2 by consultation between the parties concerned. The standard tolerances are listed in Tables 8 and 9.
Table 8 Calendered rubber sheet thickness tolerances
GB/T 3672.1--2002
mm (unless otherwise specified)
Nominal friction
Up to and including
ST1 grade
ST2 grade
ST3 grade
Tolerance of calendered film width
mm (unless otherwise specified)
Nominal width
Up to and including
SW1 grade
SW2 grade
SW3 grade
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