Rare Earth Magnet & Motor Materials worked example

Sintering Shrinkage at 5.76% shrinkage-related scrap rate: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop shrinkage-related scrap rate to 5.76%, then walk the calculation through step by step. Estimates the cost of sintering shrinkage on rare earth magnet parts from compact count, per-part material loss, and out-of-spec scrap rate.

The inputs for this scenario

  • Green compacts sintered: 8,000 parts (held at the documented default)
  • Rare earth material value lost per scrapped compact: 6.5 $/part (held at the documented default)
  • Shrinkage-related scrap rate: 5.76 % (the input this scenario stresses; the baseline uses 8)
  • Furnace run and atmosphere overhead: 5,000 $ (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Total shrinkage loss = compacts sintered x material value lost per part x shrinkage scrap rate% + furnace overhead.
  • Total sintering shrinkage cost works out to 7,995 $ at these inputs, and this is the headline figure for the scenario.
  • Sintering shrinkage cost per unit works out to 1 $ / piece at these inputs.
  • Variable sintering shrinkage cost works out to 2,995 $ at these inputs.
  • Fixed sintering shrinkage adder works out to 5,000 $ at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where shrinkage-related scrap rate sits at 8% and the headline result is 9,160 $, this scenario comes in 12.72% below the baseline at 7,995 $.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to shrinkage-related scrap rate, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It treats scrap rate as a single average and does not distinguish shrinkage from cracks versus density gradients, which have different fixes.

Results at a glance

  • Total sintering shrinkage cost: 7,995 $ (headline result)
  • Sintering shrinkage cost per unit: 1 $ / piece
  • Variable sintering shrinkage cost: 2,995 $
  • Fixed sintering shrinkage adder: 5,000 $

Run it with your numbers

  • To rerun this with your own numbers, open the live Sintering Shrinkage calculator, set shrinkage-related scrap rate to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.