Design of Jigs or fixtures

[sasi2707]

hi friends,

Should we consider the tolerance values of component during fixture design..? How extend the tolerances of fixture should stringent than component tolerance..? where I can get a example / tutorial for fixture design calculations??

sasi

 

[Belanger]

A common rule is to use 10% of the product tolerance in designing gages and fixtures. Then this tolerance is usually allocated on the side that adds material to the fixture, thus prevent a bad part from ever fitting (but perhaps occasionally rejected a borderline good part).

This idea is detailed in the ASME standard Y14.43, although there it is specific to gages. But it seems to be the same concept you are asking about.


John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[SeasonLee]

Attached example is from ASME Y14.43 Fig. B5 page 54 and 55, here is an example of 10% application and the calculation of all gage size, hope this will help you.
This gage design example utilizes the practical absolute gaging policy.

Season

 

[sasi2707]

Hi Belanger and seasonlee,

I am asking about the design of fixtures or jigs that is used to hold the component during manufacturing process..

 

[ctopher]

The fixture needs to be designed so that the part is within tolerance. If a hole in the part needs to be positioned within a certain tol, the fixture needs to be capable of holding it. Or, the fixture can be adjustable, depending on the part.

Chris
SolidWorks 11
ctopher's home
SolidWorks Legion

 

[IRstuff]

An important requirement for manufacturing fixtures is repeatability. Whatever constraints are required to ensure that the fixturing does not cause the part to be unrepeatable are what one should use.

TTFN
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[jbeckhou]

I would recommend designing the fixture or jig to hold the part rather than controlling tolerances. Talk to your tooling vendor, they should be able to help.

Petrotrim Services

http://www.petrotrim.com

 

[Belanger]

I now agree with the last few posts. The gage is one thing, but the fixture is what the OP is really interested in.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[KENAT]

Unless, as Ctopher mentions, the fixture is used to ensure a tolerance is met - as is the case with some of our fixtures. Gluing fixtures etc. often do this.

In this case you have to make sure the tolerances of your fixture will mean the resultant production parts meet tolerance.

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