Some concepts about DIN 5480 spline dimension Part 1

For some questions that I received. I will upload some tutorials about DIN 5480 dimensions. This is a tutorial explaining some concepts on dimensions of the splines ruled by DIN 5480

  1. Step 1: Reference diameter

    The tooth interlock of a shaft and hub splined connection is determined by the basic rack profile, the reference diameter, the module and the number of teeth. For example :

    DIN 5480 W 50 x 2 x 24 x 8h 

    DIN 5480 N 50 x 2 x 24 x 9H 

    W – stands for “Welle” and denotes a Shaft/External spline N – stands for “Nabe” and denotes a Hub/Internal spline

    50 is the reference diameter

    2 is the Module of the spline (size of the tooth)

    24 is the Number of Teeth in the spline

    8h is the Class of Fit. The number (8) represents the “Tolerance Class” of the spline (Not tip and root diameters). "h" The letter (h) represents the “Deviation Series” of the spline. External spline have lower case letters and internal splines have upper case letters

    DIN 5480 was structured to permit easy slip-fitting of components such as, for instance, ball or roller bearings. This condition is met by making the reference diameter equal to the bore of the bearing and then modifying the profiles of the teeth of the hub and the shaft accordingly.

    Reference diameter is not the Major or Minor diameter of the spline. (See figure below)

  2. Step 2: Shaft dimensions.

     The fit and the centering accuracy are determined by the deviations of the space widths and thicknesses as well as by the tolerances achieved or specified.

    In the case of the shaft. Recommended tolerance is h6

    Mean value of tip diameter. 49.52 mm

    Maximum 49.6 mm ( in this case is equal to the nominal value)

    Minimum 49.44 mm

    Mean value of root diameter. 45.54 mm

    Maximum 49.6 mm

    Minimum 49.44 mm 

    See figure below.

  3. Step 3: Hub Dimensions

    In the case of the Hub. 

    Mean value of tip diameter. 46.08 mm

    Maximum 46.160 mm 

    Minimum 46 mm (in this case is equal to the nominal value)

    Mean value of root diameter. 50.084 mm

    Maximum 50.123 mm

    Minimum 50.045 mm

    See figure below.

  4. Step 4: Clearance.(Shaft and hub)

     The flanks of the teeth are used both for transmitting the torque and for centering the hub and shaft relative to one another. The diameters of the tip and root circles of the shaft differ from the respective diameters of the hub by at least the bottom clearance c (see figure below).

  5. Step 5: Basic Dimensions

    Basic dimensions in the figure below.