M3 RENISHAW, Styli stepped, silicon nitride sphere, tungsten carbide shaft
Spherical styli have the largest field of application because they have the same probing behavior in every direction. They are therefore suitable for all common measuring tasks such as measuring bores and surfaces. The larger the stylus sphere size, the larger the mechanical filter. This means that the profile of your workpiece is smoothened, which is often required in form measurement. The deviation from the ideal sphere shape is usually shown in Grade. ZEISS styli spheres have Grade 5 as standard, but can also be offered in a higher quality for special requirements.
Tungsten carbide is the most common shaft material, it combines a very good stiffness with an acceptable thermal expansion. Only the weight can have a negative effect when using large styli. The design of the stepped shaft has the advantage of a greater shaft thickness, which is reduced towards the probe element. This graduation increases the stability of the stylus while maintaining the same length. However, the usable measuring length is reduced as a result. Tungsten carbide shafts represent a good combination in terms of weight, rigidity and thermal expansion.
Silicon nitride styli are just as universally applicable as ruby styli. However, they show less material deposits when scanning aluminum or other soft materials. This does not mean that there iare no deposits here. SiN spheres also shows this problem, the effect only occurs at a later point in time in the process. Due to the almost identical hardness compared to ruby, SiN spheres are equally susceptible to material removal when measuring hard, abrasive materials.