Pulled last quarter’s log: 28% of remake tags tied to a 0.2% sintering shrinkage factor drift on multilayer zirconia; one process tweak dropped that to 13% in four weeks. Any guesses which control did it — daily furnace verification puck, CAM toolpath update, or a hard stop on accepting scans without complete buccal bite?
Daily verification puck fixed it for us: we run a 20 mm puck first thing, log nominal vs actual, and auto-lock the furnace if drift exceeds 0.05 mm — caught a ‘slow bake’ from a fouled thermocouple and remakes fell about 40%; small caveat, we still validate the CAM shrinkage table per zirconia lot. @OP did you tie the control to lot-specific shrinkage or keep it global?
Leaning CAM toolpath update: once we turned on “layer‑aware shrink comp,” tied shrink to the blank barcode, and bumped margin offset +10 µm, our multilayer remakes fell about 40% in 3 weeks — death by a thousand microns… @s_wilkinson88’s puck check is gold, but the big lever was CAM; did you also lock cervical‑down orientation in nesting?
And my bet’s the hard stop on incomplete buccal bite — once we went ‘no bite, no mill’, the ‘shrink drift’ tags mostly vanished because they were occlusion, not material. Tiny caveat: we also standardized a 20‑min pre-dry before sinter to keep multilayer behavior predictable. Did your spike skew posterior units?
Do you ever switch between a single crown and a full‑arch load in the same firing? We killed a similar “0.2% shrinkage factor drift” by adding a cheap alumina dummy ring to normalize load mass and always keeping the sagger in the same center slot; within three weeks our multilayer runs stopped wandering. It won’t fix occlusion issues, but it tamps down the slow‑bake drift without leaning on a daily puck.