Styli Ball Materials – Ruby

The choice of materials for the stylus tip and stem is critical.  A range of stylus materials are available each optimised to suit different measurement tasks.

Ruby 

The industry standard and the optimum stylus ball material for a vast majority of measurement applications, ruby is one of the hardest known materials. Synthetic ruby is 99% pure aluminum oxide which is grown into crystals (or “boules”) at 2000 °C using the Verneuil process.

The boules are each cut and progressively machined into a highly spherical form. Ruby balls are exceptionally smooth on the surface, have great compressive strength and a high resistance to mechanical corrosion.

Very few applications exists where ruby is not the preferred ball material, however there are two applications where balls manufactured from other materials are recommended.

A small ruby boule, still attached to the rod, produced by the Verneuil process.

 

 

 

 

 

 

Heavy duty scanning applications on aluminum.

Because the materials attract, a phenomenon known as ‘adhesive wear’ can occur, which involves build up of aluminum from the surface onto the ball. A better ball material for such applications is silicon nitride.

Heavy duty scanning applications on cast iron.

Interaction between the two materials can result in ‘abrasive wear’ of the ruby ball surface. For such applications, Zirconia balls are recommended.

Ruby Stylus