The addition of a calender machine to a pyrolytic graphite sheet production plant

Abstract

This thesis documents the process and challenges of adding a new calender machine to AvCarb Material Solutions' pyrolytic graphite production plant. Before the machine could be used for mass production, several experiments needed to be conducted to better understand the capabilities of the machine. A process control procedure was designed to set up the machine to produce parts within specification. By using a one-factor-at-a-time approach, the process capability (Cpk) ofthe calender machine can be significantly improved. Additionally, the calender machine was used to investigate the significance of common defects on the uncalendered material. Experiments show that spots that are 3 millimeters or less, scratches, and certain ripples do not cause a destructive effect on the calendered sheet; therefore, sheets with these defects can be safely passed through the quality inspection stage. Foreign object debris causes bubbles, which are destructive effects, to appear on the calendered sheet; therefore, sheets with foreign object debris should not pass inspection. However, if the foreign object debris is physically removed from the sheet before calendering, the resulting sheet will not have any destructive defects. Thus, by not rejecting uncalendered sheets with certain defects, AvCarb can improve its process yield. Additionally, a thermal conductivity test apparatus was designed and used to determine that the calendered heat spreader is 70% more thermally conductive than its uncalendered counterpart.