Silicon Nitride Styli
On August 23, 2003, United States Patent 6,609,308 was awarded to Q-Mark Manufacturing Inc. for drilled silicon nitride balls.
What is silicon nitride?
It is an extremely hard hybrid ceramic (Si3N4) with a very low coefficient of friction. It takes a polished finish better than many other materials. Silicon nitride balls are commonly used in machine tool spindle bearings and aircraft flap actuators to provide longer service life.
Why are silicon nitride ball styli better than ruby ball styli?
When ruby balls contact soft metals - aluminum, for example - they tend to accumulate tiny bits of the material on the ball. Over time, this build-up of metal on the ruby ball can result in measurement errors. When this occurs, the stylus must be discarded.
When ruby balls are used on hard or abrasive materials, they can develop flat spots due to wear. When the ball develops a flat spot, the stylus should be discarded.
Silicon nitride has a significantly lower coefficient of friction than ruby. It's extremely hard, too - about 78 Rc. Therefore, silicon nitride balls exhibit less wear and don't tend to accumulate material on their surface like ruby balls. Our clients report up to 5 times longer tool life in certain applications using silicon nitride balls instead of ruby.
Q-Mark offers hundreds of CMM styli with drilled silicon nitride balls. We can put a drilled silicon nitride ball on any Q-Mark stylus with 1 mm ball or larger. Just add "-SN" to the end of any of our part numbers. We'll do the rest!