Recovering a German pump OEM from a 12% impeller rejection rate
Incoming rejection rate at the buyer
12.3%0.8%
Measured over a 96-day programme
Volume
2,400 impellers per year, three geometries, sizes Ø180–Ø340 mm
Client
Pump manufacturer, Germany
The situation
A pump OEM in North Rhine-Westphalia was rejecting roughly one in eight CF8M impellers from an incumbent foundry on balance and wall-thickness grounds, and was absorbing the cost of returning failed units from Germany.
What was done
- The requirement was re-specified against a measurable acceptance test before any price was discussed — in this case incoming rejection rate at the buyer measured on incoming goods, not on a supplier’s own paperwork.
- Process control was changed to hold that measurement: process at Investment casting (lost wax), silica sol shell, material at CF8M / ASTM A351 (316 equivalent).
- Evidence was tied to each lot so the buyer could verify the claim rather than trust it. That is why the programme ran 96 days: the first 5 lots were used to prove stability before volume was released.
Evidence you can ask to see
Buyer inbound inspection records (before/after), balance test certificates per lot, spectrometric chemistry reports
These are buyer-side or third-party records, not supplier marketing. Where a document is commercially sensitive we will ask the buyer for permission before sending it, and say so rather than sending a redacted page that proves nothing.
The part involved
| Process | Investment casting (lost wax), silica sol shell |
|---|---|
| Material | CF8M / ASTM A351 (316 equivalent) |
| Size range | Ø120–Ø420 mm, impeller diameter |
| Wall thickness | ≥3.5 mm minimum, cast-in |
| Dynamic balance | ISO 1940-1, grade G6.3 |
| NDT | Dye penetrant per ASTM E165; radiography on request |
Comparable projects
- Delivering a PPAP Level 3 dossier in 6 weeks for a Tier-1 bracket launchDays from purchase order to approved PPAP warrant: 78 (previous programme) → 41