Tolerancias Lineales GBT1804

 

 

National Standard of the People s Republic of China General tolerance GB/T 1804-92 Tolerance for linear dimensions without individual tolerance indications replaces GB 1804-79 

This standard adopts the part Tolerance for linear dimensions without individual tolerance indications!  of international standard ISO 2768-1: 1989 General tolerance    Part I: Tolerances for linear and angular dimensions without individual tolerance indications. 1. Theme content and scope This standard specifies the general tolerance grad and limit deviation for linear li near tolerance. This standard is applicable to metal cutting dimensions and general pressing dimensions. Dimensions of nonmetal material and other process manufacturing method can refer to this standard. The limit deviation specified in this standard is applied to non fit dimensions. 2. General tolerance concept General tolerance refers to the tolerance which can be guaranteed in the workshop under the normal manufacturing conditions. The dimensions with general tolerance need not mark limit deviation. 3. General ttolerance olerance for linear dimensions 3.1. Normally the general tolerance for linear dimensions specifies four tolerance grades. Limit deviation value of lilinear near dimension please see T Table able 1; limit deviation of fillet radius and chamfer height dimensions please see Table 2. 3.2. In order to specify the linear dimensions without individual tolerance indications, the workshop general manufacturing accuracy should be considered; take the tolerance grade specified in this standard, and the detail is specified in related technical document or standard. Table 1 Limit Deviati Deviation on Value of Linear Dimensi Dimension on Tolerance grade

mm

Dimension sections 0.5~3

>3~6

>6~30

>30~12

>120~4

>400~1

>1000~

>2000~

0

00

000

2000

4000

f(fine)

"0.05

"0.05

"0.1

"0.15

"0.2

"0.3

"0.5

-

mmedium!

"0.1

"0.1

"0.2

"0.3

"0.5

"0.8

"1.2

"2

ccoarse! 

"0.2

"0.3

"0.5

"0.8

"1.2

"2

"3

"4

v  most

-

"0.5

"1

"1.5

"2.5

"4

"6

"8

coarse! 

Approved by China State Bureau of Technical Supervision Feb. 09, 1992

Implemented on Oct. 01, 1992

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GB/T 1804-92

Table 2 Limit Deviation Value of Fillet Radius and Chamfer Height Tolerance

mm

Dimension sections

grade

0.5~3

>3~6

>6~30

>30

f (fine)

"0.2

"0.5

"1

"2

"0.4

"1

"2

"4

mmedium !  ccoarse!  most coarse! V

Note: Meaning of fillet radius r adius and chamfer height please see national standard GB 6403.4 (Part fillet and chamfer). 4. Express m method ethod of linear dim dimension ension gene general ral tolerance The standard code and tolerance grade code should be marked if the general tolerance specifies in this standard are used in drawing, technical docum document ent or standard. For example, to select medium grade, it can be expressed as: GB 1804-m

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GB/T 1804-92

Annex A Concept and function of linear dimension general tolerance (Informative)  A1. General review  A1.1 Dimension, shape of part feature or position requirement of all the features is decided by their function. There are no features without function requirements. So, all the features expressed on the drawing of one part should have tolerance requirement r equirements. s.  A1.2 Give general tolerance to the features which have no function special requirements.  A1.3 General tolerance can be applied on the geometric element linear dimension, angular dimension, shape and position etc..  A1.4 The general tolerance of feature need not mark on the drawing individually; there should be a general explanation on drawing, technical document or standard.  A2 Concept of linear dimension general to tolerance lerance  A2.1 Linear dimension general tolerance refers to the tolerance can be guaranteed under the normal process conditions with the machine normally manufacturing abilities. It represents the economic manufacturing accuracy under the normal maintain and operation.  A2.2 Linear dimension general tolerance mainly is applicable to the low accuracy fits dimension. When the tolerance allowed by the function is equal or bigger than general tolerance, take the general tolerance. Except for one feature is allowed to have one tolerance which is bigger than general tolerance, and this tolerance is more economic than the general tolerance ( for example, the depth of blind hole for assembly), mark the corresponding limit deviation behind of this dimension.  A2.3 The dimension adopts the general tolerance need not to be inspected normally if the normal workshop accuracy is guaranteed.  A2.4 If one surface will have two different manufacturing processes (for example cutting and casting), take the bigger one of the linear dimension general tolerance between them according to the stipulation.  A3 Function of general tolerance Using general tolerances leads to the following advantages: a) Drawings are easier to read and thus communication is made more effective to the user of the drawing; b) The design draughtsman saves time by avoiding de-tailed tolerance calculations as it is sufficient only to know that the function allows a tolerance greater than or equal to the general tolerance; c) The drawing readily indicates which feature can be produced by normal process capability, which also assists quality engineering by reducing inspection levels; d) those dimensions remaining, which have individually indicated tolerances,

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GB/T 1804-92

will, for the most part, be those control-ling features for which the function requires relatively small tolerances and which therefore may require special effort in the production - this will be helpful for production planning and will assist quality control services in their analysis of inspection requirements; e) To avoid the unnecessary dispute between supplying and requisitioning parties because the general tolerance requirement is confirmed on the drawing which can help both parties to reach a manufacturing and sales contract.  contract. 

 ___________________  _________________ __ Additional explanation: This standard was proposed by National Tolerance and Fits Standardization Standar dization Tech Technical nical Commission. This standard is under the jurisdiction of Ministry of Machinery Industry P.R China. This standard is drafted by Standardization Institute of Ministry of Machinery Industry P.R China. This standard is drafted by Li Xiaopei and Yu Hanqing. Standardization Standar dization Institute of Ministry of Machinery Industry was entrusted to have the right of interpretation of this standard .

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