Kaimera Industries
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KM-T-02 / Production · Yield

Yield & Scrap Estimator

Rolled throughput yield, staged cost per good part, and the number of blanks to actually start — with the exact binomial answer, not the expected-value guess.

Live

A free yield and scrap estimator for multi-operation routings. Enter first-pass yield and cost for each operation plus material cost, and it returns rolled throughput yield (RTY), the true staged cost per good part — including value lost in scrapped parts late in the process — and the exact number of blanks to start, using an exact binomial calculation rather than a naive divide.

Yield & Scrap Estimator

ROLLED YIELD · COST PER GOOD PART · STARTS TO CUT
EXACT MODEL · your yields, your costs

Operations, in order

Operation
FPY %
$ / unit
FPY is first-pass yield: a part that needed rework counts as a failure here even if you saved it, because rework has its own cost and lies about your process. Track a few runs per op and use your real numbers. Running parts from the plasma table? Its cost per part from the Plasma Cut Estimator drops straight into the first row. Note that engraving last means an engrave failure scraps a fully-finished part — the breakdown panel shows what that actually costs you. For a weldment, one “unit” is the whole set of components: material is the total for every piece in the bracket, and the cut op covers cutting them all. Weld yield is where FPY gets strict — grinding out a bad bead and rewelding is rework, so it counts as a miss even though the part ships.

Batch planning

Rolled throughput yield — chance a blank survives the whole chain
94.1%
97% × 99% × 98% across 3 ops
Cost per GOOD part
$7.36
staged: scrap only eats what it consumed
If yield were perfect
$7.00
scrap premium $0.36 per part
Naive cost ÷ RTY
$7.44
overstates when scrap happens early
Starts per good part
1.063
blanks entering op 1 per part shipped

How many blanks to start

Start for 90% confidence
23
to get at least 20 good
Expected-value answer
21.3
but ~14% chance of falling short
The expected-value answer (need ÷ RTY) is what most people compute, and it is not a plan — it falls short of the target in roughly the odds shown. The confidence answer is the exact binomial: the smallest batch where the chance of getting at least your quantity clears the bar you picked. The gap between the two is the price of certainty, and it shrinks per-part as batches grow.

Where the scrap money burns

Op
Scrapped
$ / good
Share
Plasma cut
0.032
$0.16
44%
Deburr / clean
0.010
$0.06
16%
Laser engrave
0.020
$0.14
40%
Total scrap premium
$0.36
A unit that dies at an op has already absorbed material plus every op before it — so late failures cost the most even when their yield looks fine. Average waste per scrapped blank here is $5.73, well above the $3.00 material cost, which is why the per-part premium looks small while scrap still hurts. Fix the op with the biggest share, not the one with the worst yield.
Why chains hurt: no single op looks bad, but the product multiplies. Five ops at 95% each is 77% through the chain — one part in four scrapped with nobody's op "at fault." The biggest lever is always the worst op, and the worst op is usually the one nobody measures.
The model, exactly: RTY is the product of per-op first-pass yields. Cost per good part is staged — to ship one good part, 1/(yk·…·yn) units must enter op k, each carrying material plus the cost of ops actually performed on it; a unit scrapped at op 2 never consumed op 3. This assumes scrap is caught at the op that made it — if bad parts sail through to final inspection, the naive number is closer to the truth, which is itself an argument for catching scrap early. Starts-for-confidence is the exact binomial, not a normal approximation.

Where the numbers come from: you. Yields are shop-tracked facts, not published constants — count first-pass survivors for a few runs per op before trusting the outputs for anything expensive. This tool's arithmetic is test-verified; its conclusions are only as honest as the yields you feed it.

§ Common Questions

Frequently asked

What is rolled throughput yield?
Rolled throughput yield is the product of the first-pass yields of every operation in a routing. It is the probability a part gets through the whole process with no scrap or rework.
How many extra parts should I start to cover scrap?
Dividing the target quantity by yield gets you to roughly 50% confidence. To reliably hit a quantity you need to start more, which is why this tool solves the exact binomial for the confidence level you pick.
Why is scrap late in a routing more expensive?
A part scrapped at the last operation has absorbed the cost of every operation before it. Staged costing accounts for that, so late-stage yield problems show up as much larger cost per good part.

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