02. Tolerance - (1) What is tolerance? Necessity and standard of tolerance.

In the last post, we looked at GD&T - Flatness and Parallelism.

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01. Geometric Tolerance - (1) Flatness and Parallelism & Conceptual distinction.

 

In this post, we will learn about tolerance and its necessity.

Furthermore, we will find out what national standards are related to the dimensional tolerance notation.

 

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1. What is tolerance? Necessity of tolerance.

 

A. What is Tolerance?

 

- The designer's expression of the degree of deviation

from the standard dimension and shape of the workpiece.

 

- That is, tolerance is the value indicated by the designer in the drawing

and refers to the officially recognized error.

 

- The form of tolerance notation is as follows.

The form of tolerance notation

 

B. Why do we need tolerance?

 

- Tolerance is expressed as additional information on the number of stationary numbers written in the drawing,

and examples of notation are shown in the image below.

 

- The designer writes the static number 10 in the drawing,

but the producer cannot produce the same dimension as the static number.

This is because no matter how accurate the machine tool is, errors inevitably exist.

 

- Accordingly, the designer shall additionally fill in the officially recognized error, that is, tolerance,

so that the dimensions of the real (see the right side of Figure B) can be manufactured within a specific range.

Example of a tolerance notation. The real object is made based on the dimensions and tolerances written in the drawing.

 

 

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2. Standards and specifications for tolerance marking.

 

A. Criteria for indicating tolerances.

 

- Tolerance notation is based on the designer's intention.

That is, the designer writes in consideration of compatibility between the parts to be assembled.

 

- If the designer doesn't fill out the tolerance,

In principle, it is necessary to follow the normal dimensional tolerance specified in the ISO or KS standard.

 

 

B. Related specifications.

 

- Related ISO standard : ISO 2768-1

- Related KS standard : KS B ISO 2768-1

 

The above article is for reference to help the company's purchasing, sales, and design personnel.

Unauthorized distribution is prohibited.