A blow bar that “looks right” on the receiving bench can still fail on locking notch position, hardness traverse, or an unmarked heat. Pocket fit is not flight-ready. First-article inspection (FAI) on impact castings costs less than a shattered rotor incident and less than arguing about a campaign that never should have started.
This page is a receiving / FAI playbook for QA inspectors at mines, quarries, and dealer warehouses — and for buyers writing supplier quality clauses. Alloy choice stays on the HSI blow bar material selection matrix. How to read HRC/HB and toughness stays on hardness testing. Pass/fail gates and the document pack live here. Identity for reorder and reject-replace stays part number / model match. Hardness and tolerance numbers below are example gates / buyer-agreed ranges, not universal guarantees.
Answer first: what should FAI include?
Q: What should a blow bar first-article inspection include?
A: Agree gates for critical dimensions (especially locking notch and pocket fit), a multi-point hardness map on the working face and near retainers, visual/NDT for cracks and inclusions, and a document pack (dims, hardness, heat/material, markings). Reject unmarked or out-of-gate bars before they reach the rotor. Reorder by part number / model match.
When FAI applies
Run full FAI when any of these is true:
- New pattern or new revision
- New alloy family on an existing PN family
- New supplier or new melt source
- First lot after a process or tooling change
- Prior fit, breakage, or hardness complaint on that identity
After a stable FAI pass, later lots can follow an agreed sample plan — but unmarked bars and notch-critical dims should never become “visual only.”
Related impact-family change-out discipline (VSI tips / anvils / plates) is on the VSI replacement checklist. Fitment proof language for model-match castings in general is on the fitment proof / RE checkpoints page.
Table A — Feature priority (what deserves a gate)
| Feature | Why it matters | Typical control |
|---|---|---|
| Overall length / width / thickness | Clears rotor pocket | Linear dims + stock allowance note |
| Locking notch / retainer geometry | Holds bar at speed | Position, form, template |
| Mounting faces / radii | Contact & stress | Flatness / profile |
| Ends & corners | Crack starters | Visual + radius check |
| Marking (heat / alloy / PN) | Traceability | Permanent mark present & legible |
Notch and retainer geometry sit at the top of the risk list for in-rotor breakage. A bar that is only “within length” but off on notch position is not a pass.
Table B — Dimensional incoming sheet (example columns)
Use placeholder nominals tied to the approved drawing — do not invent a fake machine drawing. Copy this blank sheet into your receiving form.
| Dim ID | Nom (example) | Tol (example) | Method | Measured | Pass? |
|---|---|---|---|---|---|
| L1 length | per approved drawing Rev X | ± agreed | Tape / CMM | ||
| T1 thickness @ zone A | per approved drawing Rev X | ± agreed | Mic / ultrasonic | ||
| N1 notch position | per approved drawing Rev X | positional | Template / CMM | ||
| F1 face flatness | per approved drawing Rev X | mm (agreed) | Straight edge |
General casting CT / datum practice is covered in casting dimensional tolerances. Apply those ideas to the blow-bar features above; keep the gate list short enough that receiving actually runs it.
Table C — Hardness traverse gates (indicative)
| Zone | What to ask | Risk if skipped |
|---|---|---|
| Working face mid | HB or HRC per alloy family | Soft face → short life |
| Near notch / retainer | Local hardness + visual | Brittle notch → breakage |
| Core / opposite face (as agreed) | Confirm through-harden or intended gradient | Misleading single spot |
| Map density | ≥3–5 points agreed on FAI | Cherry-picked certificate |
Important: manganese and high-chrome expected patterns differ. Mn often looks “soft” as-supplied and work-hardens in service; high-chrome reports much higher HRC with lower toughness. Do not rank families on one HRC number — see hardness testing for method and HSI matrix for alloy choice. Agree scale (HB vs HRC), locations, and minimum map density in the purchase order before the lot ships.
Table D — Visual / NDT cues
| Cue | Action |
|---|---|
| Shrink / hot tear on working face | Quarantine; photo; supplier disposition |
| Sand inclusions at notch | Reject or grind-only if procedure allows |
| Unmarked heat / missing PN stamp | Hold — no traceability |
| Grind burns / blueing | Check hardness locally |
| Crack indications (MT/PT if in PO) | Follow PO NDT clause |
Surface finish expectations (grind, shot, as-cast notes) are summarized in casting surface finishing. Spec language for grades can reference cast steel grade equivalents without dumping full chemistry tables into the receiving form.
Table E — Document pack to request
| Document | Purpose |
|---|---|
| Dimensional FAI report | Measured vs drawing |
| Hardness map | Points + method + scale |
| Material cert / heat | Traceability (desensitized examples only in shared packs) |
| Heat-treat record | Process confirmation |
| Visual / NDT record | As purchased |
| Photos of markings | Match PN / model match |
A real pack contains measured values, method notes, and legible marking photos. A single-spot hardness line with no map is not an FAI pack.
Table F — Disposition & RFQ follow-up
| Result | Next step |
|---|---|
| Pass FAI | Release; keep pack with lot |
| Conditional | Written deviation + use-as-is / rework |
| Fail | Quarantine; photo set; reorder by PN / model match |
| Recurring fail | Escalate alloy / pattern / foundry process — see fitment proof |
For reject-replace orders, use the PN / model-match RFQ fields and attach the failed FAI photos and dim sheet. Fictional placeholder only: PN-BLOW-EX-001 / model match — never present catalog competitor numbers as foundry SKUs.
Tie to alloy choice (one paragraph)
FAI does not pick the alloy. If breakage clusters near the notch on a high-chrome bar in high-impact duty, or if face wash is extreme on manganese in fine abrasion, revisit the HSI material matrix after you confirm the bar met dimensional and hardness gates. Do not use FAI failure as a silent alloy change without a written revision.
FAQ
HB vs HRC on high-chrome — which should receiving use?
Use the scale agreed on the drawing or PO. High-chrome is commonly reported in HRC; manganese more often in HB. Conversions are approximate — if the PO says HB, ask for HB. Method detail: hardness testing.
Is a single-spot hardness cert enough for FAI?
No. Agree a multi-point map (typically three to five or more points) covering working face and near-retainer zones. Single-spot certs are easy to cherry-pick and miss notch-adjacent soft or brittle regions.
Can receiving skip CMM if a template exists?
For notch and pocket-critical features, a calibrated template or CMM (as agreed) is the control. Tape-only checks on length are not a substitute for notch position. Match method to the feature risk in Table A.
What if the drawing is missing — can we use a worn sample?
A worn sample can support reverse-engineering and a new agreed dim list, but it is not a silent substitute for Rev X. Escalate to a fitment proof / RE flow with photos and marking evidence before releasing a first lot.
What sample size after FAI pass?
Agree it in the PO. Typical practice: full FAI on first article, then a defined sample per lot. Critical notches and markings remain mandatory checks even on reduced sampling.
How fast can a replacement lot ship after a fail?
It depends on stock, pattern status, and whether the failure was dimensional, hardness, or marking. Ask for a written week range on the reorder quote. This page does not invent day counts.
Should unmarked bars ever be installed “to keep the plant up”?
No. No heat / PN stamp means no traceability for claims, no link to hardness/material certs, and no safe disposition trail. Hold unmarked bars.
Close
Run Tables B–E on the receiving bench before bars reach the rotor. Notch geometry, multi-point hardness, visual/NDT, and a real document pack beat “looks identical.” Reorder and claims stay on part number / model match.
GUBT is a source foundry for model-match impact wear castings. To request a foundry FAI pack with your next order, send drawing Rev + PN / model match + duty notes to info@gubtcasting.com or Contact Us.
