Styli Grades

CMMs styli are supplied in different Grades.  With the increased use of very high accuracy CMMs, the specification of the stylus ball is a significant factor when calculating error budgets. Typically styli is supplied to Grade 5 standard.

When precision counts.

The sphericity of your stylus ball can affect your CMM measurements. To ensure the accuracy of your measurements, use a minimum of AFBMA 3290 / DIN 5401-11.1993 Grade 5 stylus balls with a sphericity of 0.13 μm; not the lesser Grade 10 balls that some suppliers provide. The optional Grade 3 balls, have a sphericity of 0.08 μm. The table below shows the tolerances to which various ball grades must conform:

Styli Grades

 

Styli Specifications Definitions

 

Nominal ball diameter DW: The diameter value used to identify the ball size.

Ø Deviation: The difference between the largest and smallest diameters of one ball.

Deviation Roundness: The greatest radial distance in any radial plane between a sphere circumscribed around the ball surface and any point on the ball surface.