Star Wheel Design Considerations

Boss Diameter

Typically, this is often a less critical measurement and is normally linked to the bore size. On a 40mm² bore, for example, the boss diameter will usually be around 70mm. It is important when considering the use of spacers and collars together with the star.

Bore Size

Screening stars are fitted to metal shafts. These are connected to a powered drive chain which rotates the shafts when in use . The bore size is usually square and dictated by the size of the shaft on which it is to be fitted (typically 32, 40 and 50mm)

Overall Diameter

This is normally taken as a nominal measurement from the tips of the fingers or the centre of the finger radii. Smaller stars could be around Ø160mm, with common aggregate screening stars usually in the range of Ø230-260mm.

Overall Thickness

This is the measurement from one face of the boss to the other, not the
thickness of the finger and is usually around 40mm. Some users may require a + or – tolerance to enable the stars to fit the parent machine.

Finger Radius

The curved tips of the fingers are the most exposed area of the star and the radius helps maximise durability. The size of the radius will vary from star to star and some designs even carry an elongated tip.

No. of Fingers

This is the actual number of fingers a star has. This can range from 4 or 6 through to 14 or 18. Some designs may also include a number of elongated fingers designed for cleaning.

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