Apr 20th, 1:00 PM - 4:00 PM


Design of Experiments to Maximize Production Throughput of ZnO Varistors

Faculty Sponsor

Chad Watson


Varistors are critical components of many electrical circuits due to their electrical current shunting capabilities. Sandia National Laboratories’ (SNL) Ceramics and Glass Processing Department fabricates ZnO varistors for high voltage applications. These varistors are core drilled from a uni-axially pressed ceramic billet. Because ceramics can be easily damaged, the drilling process is timeintensive. Damage to the core while drilling can cause the completed varistor to fail catastrophically. The goal for this project is to maximize the drilling rate while minimizing defects introduced from drilling. The SNL drilling setup was replicated using the PCNC 1100 milling machine located at Boise State University’s (BSU) New Product Development Laboratory. Design of Experiments (DOE) was used to evaluate and characterize factors affecting the core drilling process. The characterization techniques utilized included optical and electron microscopy along with optical profilometry. Initial screening determined the factors statistically significant to the experiment and a full factorial was conducted. From the DOE model, the optimal factors were chosen to produce acceptable varistor cores at the fastest possible rate.