DIN 5480 transition fit?

[james176]

Hi,can anyone explain the difference between interference, transition and clearance fits in DIN 5480? it seems to me that if a pair of transitional fit splines are made to maximum material condition then there could be problems with the splines fitting together because of the possibility of negative clearances.

Thanks for your help.

Louise

 

[Occupant]

If you pair "H" with "j" - "H" for the bore, "j" for the shaft, you'll have a transition fit that could result in some, but minimal, interference. If you use "H" with "h" you could have a zero to zero condition, but no interference. Every thing else is either a clearance or interference fit.

 

[james176]

Occupant,

thank you for your response. Your example of using say 9H and 8j allows for at the most -.014 (.00055) That seems like a reasonable amount
for a transition fit connection. What confuses me is the examples given in the DIN 5480-1 2006 where the transition fit examples shown in table 9
show potential interferances of -.070 (-.0028")

for a rough transition fit and -.056 (-.0022) for fine transition fit. It is clear that they could
end up being press (interferance)fit splines if they are cut anywhere near their maximum material sizes. I guess what I'm looking for are actual
rules or distictions between a transitional and interferance fits. Please see the attached picture.

Thank You.

 

[Occupant]

I don't have a complete table, what I have only shows commonly used pairings e.g. for a hub 3H7 you get as the low limit 0.0 (of course), high limit 0.0012. With the shaft 3P6 low limit 0.0014, high limit 0.0021. Meaning: min. interference of 0.0002, max. interference of 0.0021 - everything in inches and changes with the diameter. Values shown in the table are only examples - make your own selection.

 

[Tmoose]

What does your application require?

You seem to have ruled out any interference. If that is so, then a transition fit is not for you, because as you have determined, there is that possibility.

 

[james176]

Hello,

I am working on a spread sheet which will name the type of fit once the user selects the deviations and tolerances. For example if the user selects 8H 8n for the spline
connection then the fit type column would be named "fine transitional fit" or if the user selects 8H, 8s the fit type column would be named rough transitional fit. The problem is
that there are so many different combinations of letters I'm not sure where "rough transitional" fit type would end and fine ibterferance fit would beging. to me the standard
does not make this clear. would a fine transitional fit be -.050mm / +.100mm and a rough transition be -.100 / +.050. how much potential interferance would be required to specify
the fit as a fine interferance fit and so on. I cant seem to find any rules for this.


Thanks for your help,

Louise

 

[mfgenggear]

James

do you have to use the DIN, can you not use the ANSI spec B92.1

Mfgenggear

 

[james176]

Yes,
For this project I am calculating dimensions for DIN splines. I have a program that I wrote for ASA and ANSI splines. This would be specifically for DIN 5480 splines

Thanks