M5, Styli stepped, ruby 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.
Ruby styli are the standard for almost all applications and are available in a variety of different diameters. Another advantage is that ruby spheres can be produced in very small diameters (from 0.12 mm). On the other hand, ruby has weaknesses at the continuous scanning of certain materials and surfaces. With extremely soft materials, e.g. aluminum, material from the workpiece can be deposited on the ruby surface (material deposit). Very hard and rough surfaces, e.g. castings, on the other hand, cause abrasion of the sphere (material removal). The shape of the sphere changes as a result and loses accuracy.