Formulas

Dental and Prosthetics Manufacturing Formulas: Blank Yield, Print Time, and Remake Rate

The five recurring calculations that run a digital dental lab, worked with real units and typical shop numbers so you can reproduce every result.

A digital dental and prosthetics operation runs on five recurring calculations: how many units come off a milling blank, how tightly you nest a build plate, how long a model print takes, what share of cases return as remakes, and how much lead-time buffer protects a promised ship date. Each pulls inputs from your CAM software, printer slicer, and job tracker. This guide runs the arithmetic with real units and typical shop numbers so you can reproduce every result. Pricing and target ranges live in the sibling cost and benchmark guides, so here the focus stays on the math.

Start milling blank yield with a 98.5 mm zirconia disc, 20 mm thick. Reserve a 2 mm structural rim, leaving a 94 mm usable diameter, so usable area is pi times 47 squared, about 6,940 mm squared. A single-crown nest footprint runs 18 mm by 18 mm, or 324 mm squared, once you add a 3 mm connector and spacing. Theoretical count is 6,940 divided by 324, about 21 crowns. Real packing efficiency for irregular shapes sits near 65 percent, so expected yield is 21 times 0.65, roughly 14 crowns per disc. The Milling Blank Yield calculator automates this from your part envelope and disc geometry.

Batch nesting utilization equals summed part area divided by blank area, times 100. Take those 14 crowns at 200 mm squared of true projected area each, so 2,800 mm squared sit inside the 6,940 mm squared usable disc, a utilization of 40 percent. Area utilization always reads lower than unit packing because crowns are round and leave interstitial waste. For thermoform and print plates, run the same ratio against sheet or platform area: 6 aligner arches at 55 mm by 40 mm on a 200 mm by 125 mm sheet gives 13,200 over 25,000, about 53 percent. The Batch Nesting Utilization calculator tracks this per job.

MSLA and LCD model print time depends on height, not part count, because every part on the plate cures in the same flash. Time equals model height divided by layer thickness, times seconds per layer. A 32 mm arch model at 50 micron layers is 32 divided by 0.05, or 640 layers. Per-layer time is exposure plus lift and retract: 2.5 s plus 4.0 s, or 6.5 s. Total is 640 times 6.5, about 4,160 s, roughly 69 minutes, whether you print one model or nine. The Dental Model Print Time calculator computes this and divides by plate count for per-unit minutes.

Remake rate equals remakes divided by units shipped, times 100, over a fixed window. If you shipped 620 crowns last month and 34 came back for remake, that is 34 over 620, about 5.5 percent. Track it by cause code such as margin fit, contact, shade, or fracture so the percentage points somewhere actionable. Watch the denominator: count units shipped, not cases, because a 3-unit bridge is three units of exposure. The Remake Rate calculator separates internal rejects caught before shipping from field returns, which matters because the two carry very different recovery paths.

Scan-to-production lead-time buffer sizes the safety time between accepting a scan and the committed ship. Model total cycle as the sum of stage means, then add a buffer scaled to variability: buffer equals z times the combined standard deviation. If design, mill, sinter, and QC average 26 hours combined with a 6-hour standard deviation, a 95 percent service level uses a z of 1.65, so buffer is 1.65 times 6, about 10 hours. Commit to 36 hours, not 26. The Scan-to-Production Lead-Time Buffer calculator runs this from your stage timestamps and target service level.

Every input traces to a system you already run. Disc geometry and part envelopes come from the CAM nest report, layer count and exposure come from the slicer profile, remake counts come from the job tracker or QC log, and stage means and standard deviations come from timestamped routing data. Recompute blank yield whenever you change connector size or disc thickness, and recheck print time after any resin or layer-height change, since moving from 50 micron to 100 micron layers halves layer count and cuts print time by nearly half. Rerun the numbers on every process change, not once a year.

Published 2026-07-02.