PPAP Level 3 for Aluminum Castings: What Automotive Buyers Actually Check

# PPAP Level 3 for Aluminum Castings: What Automotive Buyers Actually Check

If you are a casting supplier preparing your first PPAP Level 3 submission for an automotive customer, the AIAG PPAP manual describes what is required. What it does not tell you is which elements receive the most SQE scrutiny and where casting suppliers specifically fail on first submission. This post walks through the full 18-element package from a casting supplier's perspective — what each element requires, how casting-specific manufacturing creates unique documentation challenges, and where to invest preparation time to avoid a conditional approval or rejection.

PPAP Levels 1-5 Refresher: What "Level 3" Actually Means for a Casting Supplier

PPAP has five submission levels, differentiated by how much documentation is submitted to the customer vs. retained at the supplier:

• •Level 1: Part Submission Warrant only (PSW). No supporting documentation submitted.
• •Level 2: PSW with product samples and limited supporting documentation.
• •Level 3: PSW with full supporting documentation submitted to the customer. Default level for new parts.
• •Level 4: PSW and other requirements as defined by the customer.
• •Level 5: PSW with full supporting documentation reviewed at the supplier's manufacturing location.

Level 3 means you submit the complete package and the customer's SQE reviews it before approving the PSW. For Level 5, the SQE comes on-site. For new aluminum casting programs, Level 3 is standard on new part launches and significant design or process changes. The AIAG PPAP reference manual (4th edition) governs; your customer's supplier quality manual may add requirements.

The 18 PPAP Elements: Which Ones Are Non-Negotiable for Aluminum Structural Castings

All 18 elements must be addressed in a Level 3 submission — "not applicable" must be justified, not simply omitted.

• •Design Records
• •Engineering Change Documents
• •Customer Engineering Approval
• •Design FMEA (DFMEA)
• •Process Flow Diagram
• •Process FMEA (PFMEA)
• •Control Plan
• •Measurement System Analysis (MSA) Studies
• •Dimensional Results
• •Records of Material/Performance Test Results
• •Initial Process Studies (Cpk/Ppk)
• •Qualified Laboratory Documentation
• •Appearance Approval Report (AAR)
• •Sample Production Parts
• •Master Sample
• •Checking Aids
• •Customer-Specific Requirements
• •Part Submission Warrant (PSW)

For aluminum castings, the elements receiving the closest SQE attention are PFMEA (6), Control Plan (7), MSA/Gage R&R (8), Initial Process Studies/Cpk (11), IMDS/Material Records (10), and PSW (18). Elements 1-3 are typically OEM-owned for outsourced designs; elements 5-18 are supplier-owned.

Design Records and Engineering Change Documents: What the Casting Supplier Owns vs. the OEM

For cast-to-print programs, the design record is the engineering drawing owned by the customer. The supplier's obligation is to have the current released drawing on file and confirm production parts were made to that revision. Engineering change documents (element 2) apply when a design change has been approved but not yet reflected in the released drawing; the supplier confirms production parts incorporate the approved changes.

DFMEA (element 4): Typically OEM-owned for cast-to-print designs. If your customer shares a DFMEA for review, contribute casting-specific failure modes — porosity, as-cast geometry variation, heat treatment deviation. Do not sign off without confirming casting process risks are adequately captured. If the customer does not share the DFMEA, note that design responsibility and DFMEA retention rest with the customer. The common gap: casting suppliers who assume no DFMEA responsibility and disengage from the design review entirely.

PFMEA for Casting: Common Gaps — What SQEs Look for That Suppliers Miss

The Process FMEA (element 6) is where casting suppliers most commonly receive SQE pushback. Generic manufacturing templates are not acceptable for structural castings. A casting PFMEA must include:

• •Failure modes linked to specific process steps. Die heating, metal preparation, filling, holding, ejection, heat treatment, and machining each need individual failure mode analysis — not a single "casting" row.
• •Defect-specific failure modes with calibrated ratings. Cold shut, misrun, gas porosity, shrinkage porosity, hot cracking, and dimensional out-of-spec must appear with effects, severity ratings reflecting actual downstream risk, and detection controls matching the control plan.
• •Detection controls must match reality. Visual inspection that misses subsurface defects is a low-effectiveness control — the detection number must reflect this, driving RPN high enough to warrant additional controls such as dye penetrant or X-ray.
• •Heat treatment failure modes must be included. Under-aging, over-aging, and solution treatment excursions are real failure modes for A356-T6 castings with defined effects on yield strength and elongation.

SQEs expect to see RPNs above threshold (typically RPN greater than or equal to 100 or severity greater than or equal to 9/10) with documented corrective actions on safety-related structural castings. A PFMEA with every RPN below 50 and no actions is not reflecting real risk.

Control Plan Requirements: Frequency, Reaction Plans, and Who Signs

The Control Plan (element 7) documents what is controlled, at what frequency, by what method, and what the reaction plan is when something is out of control.

Process parameters: Filling pressure, holding pressure, holding time, metal temperature, die temperature by zone, and cycle time — each with a control range, measurement method, frequency, and specific reaction plan. "Call supervisor" is not a reaction plan; the control plan must specify the decision (hold the lot, 100% inspect, segregate affected parts).

In-process and finished part inspection: Which features are measured at which frequency, with exact gauge or CMM program identified; dimensional sample plan; mechanical test frequency (lot-based tensile, hardness); NDT requirements (dye penetrant, X-ray sampling plan); and IMDS compliance.

Who signs: Quality engineer, process engineer, and customer representative (or documented customer approval). Unsigned control plans are incomplete.

Measurement System Analysis (Gage R&R): Typical Failures in Casting PPAP Submissions

MSA (element 8) requires gage R&R studies for the measurement systems used in production inspection. AIAG MSA acceptance criteria: %GR&R below 10% is acceptable; 10-30% may be acceptable depending on application (customer approval required); above 30% is not acceptable.

Four common failures for casting suppliers:

Casting-specific challenges ignored. Surface texture, draft, and parting line irregularities add variation at as-cast datums. The study must use the same method and datum structure as production inspection — a study on machined samples does not represent the actual measurement system for as-cast inspection.

Insufficient parts or appraisers. The standard study uses 10 parts measured by 3 appraisers, each part twice. Parts must span the tolerance range — clustering near nominal underestimates performance at tolerance limits.

Attribute studies missing. If visual inspection is in the control plan for surface defects, an attribute MSA (Kappa or signal detection study) is required.

Low discrimination ratio. A discrimination ratio below 4 means the measurement system cannot distinguish enough variation levels for process control, even when %GR&R appears acceptable.

Initial Process Studies (Cpk): What 1.67 Means and Why Your First Run Rarely Gets There

Initial process studies (element 11) require statistical evidence of process capability. The standard minimum Cpk target is 1.67, corresponding to approximately 0.57 defective parts per million at a centered process.

Cpk between 1.33 and 1.67: Provisional or conditional approval is common, with a corrective action plan and timeline required.

Cpk below 1.33: Rejection or conditional approval with mandatory 100% inspection containment until Cpk improves.

Casting-specific challenges: As-cast dimensions carry inherent variability from die wear, thermal expansion, and die closing variation. Cpk 1.67 on tight-tolerance as-cast features on a new tool is difficult on first article — document the process physics in your submission and propose an improvement plan.

What the SQE checks: Whether the study was run on a statistically valid production sample (minimum 25-30 consecutive parts from a single run — not cherry-picked), whether the distribution is approximately normal, and whether out-of-spec parts were removed. A clean histogram that omits three outlier parts is immediately suspect.

IMDS Submission: The Most Commonly Rejected Element in Casting PPAP Packages

The International Material Data System (element 10) tracks material content for ELV directive and REACH substance compliance. IMDS is consistently the most commonly rejected element in casting PPAP submissions.

Five most common rejection reasons:

• •Alloy composition declared incorrectly. The IMDS entry must declare alloy composition to element level, not just "A356 aluminum alloy." Trace elements exceeding IMDS threshold values must be declared.
• •Coatings and additions omitted. LPDC die release coatings, grain refiners (TiB2 or TiC), Sr modifier, and degassing flux additions must all be declared.
• •Incorrect node structure. IMDS requires a product to component to material to substance hierarchy. A flat single-level node receives structural rejections.
• •SVHCs not flagged. Substances on the REACH SVHC candidate list require specific flagging regardless of concentration.
• •Incorrect CAS numbers for alloy constituents or coating chemistry.

Start IMDS early — not a day-of-submission task. Most chemical suppliers publish IMDS data sheets for their products; use them rather than building substance entries from scratch.

Run at Rate: How to Plan and Document It So the Customer Accepts It First Time

Run at Rate documents that the process is stable and capable at production speed with production tooling, equipment, and personnel — not just that parts can be made.

Minimum part count: Typically 300 consecutive parts or one full production shift. Confirm the specific requirement with your customer before planning.

What must be documented: Cycle time target vs. actual (time-series log per cycle, not an average), die and metal temperature logs, fill pressure data, downtime events with reason codes, and first-pass yield with defect categorization.

Tooling and equipment: Final production tooling, production LPDC equipment, and trained production operators — not engineering staff. Deviations require a repeat run. A run interrupted by tooling or equipment faults and then resumed is not a valid continuous run.

If first-pass yield falls below target, submit with a documented action plan. Hiding a poor result is the most reliable way to receive a conditional approval with mandatory corrective action.

Part Submission Warrant (PSW): Sign-off Conditions and What "Interim Approval" Really Means

The PSW (element 18) certifies that the supplier produced parts to the engineering drawing using the documented process, with supporting documentation demonstrating a capable, controlled process.

Full PSW sign-off: All 18 elements complete and acceptable. Part approved for production shipment.

Interim approval: Granted when elements are incomplete but parts are needed for launch. Requires a defined expiration date per the AIAG manual, 100% inspection on open characteristics, and a milestone plan with named owners. An expired interim approval is a supplier quality nonconformance.

Who signs: Quality manager or engineering manager — not a coordinator without signing authority. The customer SQE countersigns. Confirm submission format before preparing the package.

Frequently Asked Questions

What exactly does "Level 3 PPAP" require that Level 2 does not?

Level 3 requires all 18 elements submitted to the customer for SQE review before PSW approval. Level 2 requires the PSW, product samples, and a limited subset — typically dimensional results and material test records, but not necessarily PFMEA, control plan, MSA, or process capability studies. The documents are not different in content; the difference is what is submitted vs. retained.

Which of the 18 PPAP elements does an aluminum casting supplier typically own vs. the Tier-1 customer?

For cast-to-print programs: elements 1-4 (design records, engineering changes, customer approval, DFMEA) are typically customer-owned. The casting supplier owns elements 5-18 — process flow, PFMEA, control plan, MSA, dimensional results, material test records, process capability studies, laboratory qualification, appearance approval, sample parts, master sample, checking aids, and the PSW. The casting PFMEA must still cover casting process failure modes regardless of who owns the DFMEA.

Our IMDS submission was rejected three times — what are the most common mistakes?

(1) Declaring only alloy composition without trace elements above reporting thresholds; (2) omitting furnace additions — grain refiners, Sr modifier, degassing flux, and die release coating residues; (3) incorrect node structure — missing the component/material/substance hierarchy; (4) incorrect CAS numbers; (5) not flagging SVHCs above 0.1% concentration. After a third rejection, request a technical call with the customer's IMDS administrator — they can identify the specific rejection reason, which is often more informative than the automated rejection message.

What Cpk targets should I realistically expect on a first PPAP submission, and what happens if we miss 1.67?

For as-cast features on a new die, Cpk 1.33 is achievable with good die design and process control; Cpk 1.67 is achievable on features with generous tolerances but difficult on tight-tolerance as-cast features. For machined features, Cpk 1.67 is typically achievable after process optimization. If you miss 1.67, document the actual Cpk, provide distribution data, propose a corrective action plan with timeline, and offer 100% inspection containment. Most customers grant interim approval for non-safety-critical characteristics; safety-critical characteristics with Cpk below 1.33 require immediate containment and customer engineering concurrence.

What level of PFMEA detail is expected for an aluminum LPDC structural casting?

Casting-specific failure modes are required — generic templates do not meet the standard for OEM SQEs. The PFMEA must trace to each process step: metal preparation, die condition, filling, solidification, heat treatment, and inspection. Each failure mode must have a defined customer effect, a calibrated severity rating, and detection controls matching the control plan. For safety-rated structural castings, severity 9 or 10 failure modes with no special controls will not pass SQE review.

What constitutes a valid run at rate — minimum part count, duration, and what data must be collected?

A valid run at rate uses production tooling, production equipment, and production operators; runs for the duration or part count in your customer's PPAP requirements (commonly 300 consecutive parts or one full production shift); and collects a cycle time log per cycle, critical process parameter data, downtime events with reason codes, and first-pass yield with defect categorization. A run interrupted by tooling or equipment faults and then resumed is not a valid continuous run — document the interruption and discuss with the customer whether a repeat is required.

If our PPAP is approved with interim approval, what are the standard conditions and timeline?

Interim approval requires a defined expiration date per the AIAG PPAP manual. Typical conditions: 100% inspection on characteristics with open Cpk or MSA issues, a milestone plan with specific dates for each open element, and a named owner for each item. Typical timelines: 90 days for process capability improvements; 30 days for IMDS items. If you cannot close open items by the expiration date, request an extension in writing. An expired interim approval without documented extension is a supplier quality nonconformance.

Why Engineers Work With Bohua Cast

Bohua Cast is an ISO 9001 certified manufacturer running LPDC and gravity die casting with a quality system designed for automotive supply chain requirements. The engineering team engages early in program development — DFM review, PFMEA development, and control plan drafting begin before tooling is committed, not after first article. Sample programs deliver dimensional reports, material certifications, and NDT data structured for PPAP submission. If your program requires Level 3 PPAP, including MSA studies, initial process capability documentation, IMDS submission, and run at rate planning for aluminum structural castings, contact the Bohua Cast engineering team to discuss program requirements and timeline.