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  • Please advise - 1. Shaft, Housing chamfer angles ? 2 - fit tolerance ?

    Discussion in 'The main mechanical design forum' started by Yuri, Nov 23, 2013.

    1. Yuri

      Yuri Member

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      [h=3]Hi all,[/h]
      I am new and need an advice about shaft and housing chamfer angles ? Medias.ina says 10-15 degrees angle for ease of bearing instalation (it seems small to me). Also find a lot of recomendations for 15 to 30 degrees if sealings are to be instaled.

      However I see a lot of 1mm x 45 degrees chamfers over the internet. What angles are used in practice ?

      My second questions is what will be the appropriate fit for Drive Shaft and Hub ?
      Shaft d- 35mm j5 not shure about the Hub bore ??? Both are SS, I have a key 10x8x50 mm (DIN 6885A) and moment - 200 Nm looking for ease of installation without sacrificing function.

      Should I look for Locational clearance fit or Locational transition fit ?
       
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    3. eckcop

      eckcop Member

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      When first putting the bearing on the shaft, small chamfers align the bearing to the shaft better, with less chance of marking the shaft.

      45 degree chamfers remove a sharp edge, for handling.

      I'd go for a Locational transition fit, something like a H6/j5, probably overkill for 200Nm with a key.
       
    4. kevin136

      kevin136 Well-Known Member

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      Hi man,
      I have exprience for O-ring sealing,using 20 degree. 45 degree usually,for deburring.
       
    5. Yuri

      Yuri Member

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      Thanks for the replies. Will do H6 or H7 hub bore and 30 degree chamfers.
       
    6. Paul.R

      Paul.R Member

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      Hi Yuri,

      A shallow angle like 10-15 degrees is good for a bearing lead in. A 45 degree chamfer is often used to simplify machining because most edges are broken with a 45 degree chamfer: it saves the machinist having to change his tooling.

      If you have a press fit or close transition fit, I would recommend a lead in no larger than 30 degrees - preferably 15 degrees. At the close tolerances used for bearing fits, it can be difficult to assemble if the angle of the chamfer is too large: the shaft will tend to cock to one side and bind against the bore.

      Regarding the appropriate for a driveshaft and hub, that would depend on your assembly configuration. Have a look at the following link: http://medias.ina.com/medias/en!hp.tg.cat/tg_hr*ST4_1652155275 , specifically at the 'Conditions of Rotation' and 'Shaft Tolerances for radial bearings'.

      That being said, H7 is pretty common in my experience.
       
    7. Yuri

      Yuri Member

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      Medias.ina have a lot of good information. Sorted out the bearing fits. My bearing housings are H7 and M7 (for the stationary outer ring side)

      My question was for Sheave hub that slides over the shaft. I think I sorted this also with help from this forum and linkedin group
      Will make the fit j5 - H6 or H7

      Will upload a 3d model of the unit for you to criticize the desig. I have some doubts.
       
    8. Yuri

      Yuri Member

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      Also can somebody let me know how to read this column of the tolerance table ? I see it's about first, second and third choices. not shure about the numbers ?

      For example if you have non standart shaft j5 and you want sliding fit. Do you check the difference of the listed prefered fits and then try to find a hole fit that will provide the same difference ?

      [​IMG]
       
    9. Alfred Putter

      Alfred Putter Member

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      Seal supplier catalogues will give you the recommended angle
       
    10. eckcop

      eckcop Member

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      The numbers beside the letters are for the "BASIC SIZE" or approximate diameter in mm. These diameters are F(irst), S(econd),and T(hird) choices. So if for example you want a hole 'about 13mm', 12mm would be the First choice (F12), 14mm the Second (S14) and 13mm the Third (T13).

      Very crudely; odd sizes can cost more for machining and are harder to gets parts/tools/stock for.

      From an old Machinery's Handbook; an RC2 sliding fit for a basic size of 1.19 – 1.97", would have a clearnace of 0.4 to 1.4 thou. Given the tolerance of your shaft, you could pick the hole tolerance to suit the clearance.
       
    11. Yuri

      Yuri Member

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      Thanks, seem my table is not full I have only sizes to 22 that's why I was not shure if this are dimensions.

      Will start a new thread about loads on shafts and when to consider fatigue
       

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