Engineering:Limits and fits: Difference between revisions

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In [[Engineering:Mechanical engineering|mechanical engineering]], '''limits and fits''' are a set of rules regarding the dimensions and tolerances of mating machined parts if they are to achieve the desired ease of assembly, and security after assembly - [[Physics:Fit (manufacturing)|sliding fit]], interference fit, rotating fit, non-sliding fit, loose fit, etc.
In [[Engineering:Mechanical engineering|mechanical engineering]], '''limits and fits''' are a set of rules regarding the dimensions and tolerances of mating machined parts. '''Limits and Fits''' are given to a part's dimensions to gain the desired type of fit'''.''' This is seen most commonly in regulating shaft sizes with hole sizes.<ref name=":4">{{Cite web |date=2020-08-14 |title=Limits & Fits {{!}} Types of Fits Explained & Tolerance Charts |url=https://fractory.com/limits-and-fits/#:~:text=While%20limits%20and%20fits%20apply,%E2%80%93%20clearance,%20transition%20and%20interference. |access-date=2025-02-21 |website=Fractory |language=en-GB}}</ref>
Tolerances are typically specified in thousandths of an inch or hundredths of a millimetre.<ref>{{Cite web|url=http://www.pfeffer.ch/isotolerances.htm|title=ISO System of Limits and Fits (Tolerances)}}</ref>
 
'''Limits and Fits''' are standardized by the [[Organization:International Organization for Standardization|International Organization for Standardization]] (ISO)<ref name=":2">{{Cite web |date=2025-01-31 |title=ISO - International Organization for Standardization |url=https://www.iso.org/home.html |access-date=2025-02-21 |website=ISO |language=en}}</ref> and the American National Standards Institute (ANSI).<ref name=":3">{{Cite web |title=American National Standards Institute - ANSI Home |url=https://www.ansi.org/ |access-date=2025-02-21 |website=American National Standards Institute - ANSI |language=en}}</ref> Tables are used to quickly calculate required tolerances for bolt holes, shafts, mating parts, and many similar scenarios.
 
Units for '''limits and fits''' are typically specified in thousandths of an inch or hundredths of a millimeter.<ref name=":0">{{Cite web |title=ISO System of Limits and Fits (Tolerances) |url=https://www.pfeffer.ch/isotolerances.htm |access-date=2025-02-21 |website=www.pfeffer.ch}}</ref>
 
== Types of fit ==
There are three main types of fit:
 
* Clearance Fit: a fit between mating parts with positive space in-between. Parts will freely move between each other.
* Transition Fit: a fit between mating parts between the clearance and interference fit. Parts fit together easily enough so that force is not required, but will still hold together on its own.
* Interference/Press Fit: a fit between mating parts with negative space in-between. The parts will need applied force to fit together and hold firmly together once assembled.
 
These main three types of fit are umbrella categories for different sub-categories of fits. Sub-categories include sliding fit, running fit, push fit, wringing fit, force fit, tight fit, and shrink fit. Every different type of fit is used for a different type of interaction between mating parts.<ref name=":1">{{Cite web |last=Krista |date=2024-05-24 |title=The Ultimate Guide to Perfecting Limits and Fits in Metal Work - Eziil - Best Metal Fabrication Software |url=https://eziil.com/limits-and-fits/ |access-date=2025-02-21 |language=en-US}}</ref>


==See also==
==See also==
*[[Engineering:Engineering tolerance|Engineering tolerance]]
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*[[Engineering:Engineering fit|Engineering fit]]
 
* [[Engineering:Engineering fit|Engineering fit]]
* [[Engineering:Engineering tolerance|Engineering tolerance]]
* [[Geometric dimensioning and tolerancing]]
* [[Engineering:Precision engineering|Precision engineering]]
* [[Specification (technical standard)]]
* [[Tolerance analysis]]
* [[Engineering:Tolerance coning|Tolerance coning]]
* [[Tolerance interval]]
* [[Engineering:Verification and validation|Verification and validation]]


==References==
==References==
{{Reflist}}
{{Reflist}}
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==External links==
==External links==
*http://mechanical-design-handbook.blogspot.co.uk/2009/10/standards-of-limits-and-fits-for-mating.html
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* http://mechanical-design-handbook.blogspot.com/2009/10/standards-of-limits-and-fits-for-mating.html


[[Category:Mechanical engineering]]
[[Category:Mechanical engineering]]




{{Sourceattribution|Limits and fits}}
{{Sourceattribution|Limits and fits}}

Latest revision as of 17:30, 30 April 2025

In mechanical engineering, limits and fits are a set of rules regarding the dimensions and tolerances of mating machined parts. Limits and Fits are given to a part's dimensions to gain the desired type of fit. This is seen most commonly in regulating shaft sizes with hole sizes.[1]

Limits and Fits are standardized by the International Organization for Standardization (ISO)[2] and the American National Standards Institute (ANSI).[3] Tables are used to quickly calculate required tolerances for bolt holes, shafts, mating parts, and many similar scenarios.

Units for limits and fits are typically specified in thousandths of an inch or hundredths of a millimeter.[4]

Types of fit

There are three main types of fit:

  • Clearance Fit: a fit between mating parts with positive space in-between. Parts will freely move between each other.
  • Transition Fit: a fit between mating parts between the clearance and interference fit. Parts fit together easily enough so that force is not required, but will still hold together on its own.
  • Interference/Press Fit: a fit between mating parts with negative space in-between. The parts will need applied force to fit together and hold firmly together once assembled.

These main three types of fit are umbrella categories for different sub-categories of fits. Sub-categories include sliding fit, running fit, push fit, wringing fit, force fit, tight fit, and shrink fit. Every different type of fit is used for a different type of interaction between mating parts.[5]

See also

[edit]

References

  1. ↑ "Limits & Fits | Types of Fits Explained & Tolerance Charts" (in en-GB). 2020-08-14. https://fractory.com/limits-and-fits/#:~:text=While%20limits%20and%20fits%20apply,%E2%80%93%20clearance,%20transition%20and%20interference.. 
  2. ↑ "ISO - International Organization for Standardization" (in en). 2025-01-31. https://www.iso.org/home.html. 
  3. ↑ "American National Standards Institute - ANSI Home" (in en). https://www.ansi.org/. 
  4. ↑ "ISO System of Limits and Fits (Tolerances)". https://www.pfeffer.ch/isotolerances.htm. 
  5. ↑ Krista (2024-05-24). "The Ultimate Guide to Perfecting Limits and Fits in Metal Work - Eziil - Best Metal Fabrication Software" (in en-US). https://eziil.com/limits-and-fits/. 

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External links

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  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named :4
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named :2
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named :3
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named :0
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named :1
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