Guide
How should you use PPAP for non-automotive parts, and when is Level 3 worth asking for?
PPAP is the Production Part Approval Process: a documented package in which a supplier shows that its production process, run at production rates with production tooling, makes parts that meet every requirement on the drawing and purchase order. It was written for the automotive supply chain, but the logic works for any OEM that wants evidence of a stable process before it releases volume orders.
By Saola Manufacturing engineering team · Published · Updated
This guide is for mechanical engineers and sourcing managers at industrial, medical-equipment, fluid-control and machinery OEMs who have been handed a supplier-quality requirement that says “PPAP” and need to decide what that should mean for a die-cast, machined or stamped part. It explains what a Level 3 submission contains, which of the elements carry real information for a cast and machined component, how to write a smaller package that a supplier can price, and what changes when the supplier is overseas. Level definitions and element names follow the AIAG manual; the scoping advice is engineering guidance, not part of any standard.
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What is a PPAP Level 3 submission?
Level 3 is the default submission level in the AIAG PPAP manual: the supplier sends the Part Submission Warrant, sample parts and the complete set of supporting records to the customer. Unless a purchase order names another level, a request for “PPAP” is usually read as Level 3.
The manual defines five levels. They differ in how much of the evidence is sent to the customer and how much is kept at the supplier and shown on request. The records themselves are meant to exist at every level; what changes is where they are reviewed.
| Level | What goes to the customer | Where it fits outside automotive |
|---|---|---|
| Level 1 | Part Submission Warrant only (plus an appearance approval report for appearance items) | Simple, low-risk parts from a supplier you already trust |
| Level 2 | Warrant with sample parts and limited supporting data | Revisions of an approved part, or commodity features |
| Level 3 | Warrant with sample parts and complete supporting data | New parts, new suppliers, new tooling, safety or sealing functions |
| Level 4 | Warrant and other requirements as defined by the customer | The usual home of a scoped “PPAP-lite” list |
| Level 5 | Warrant, samples and complete data, reviewed at the supplier’s plant | When you plan an on-site process audit anyway |
Two practical points follow from the table. First, Level 3 is a lot of paper for a bracket, and asking for it on every part number tells the supplier you have not decided what matters. Second, Level 4 is the level most non-automotive buyers actually want: it lets you name exactly which records you need, and the warrant still commits the supplier to the rest being on file.
The warrant is the heart of every level. It is a signed declaration, tied to a part number and drawing revision, that the parts were made with production tooling and processes and meet all requirements. If you take nothing else from PPAP, take the warrant: it turns a verbal “we can make it” into a dated, signed statement about a specific revision.
Why are non-automotive OEMs asking suppliers for PPAP?
Because it is the best-known ready-made format for proving a process before volume, and because aerospace and other sectors have written their own versions of it. Many industrial quality engineers also came from automotive and carry the vocabulary with them.
Aerospace formalized the idea in SAE AS9145, issued in 2016, which sets requirements for advanced product quality planning and describes production part approval as the output of that planning: evidence that the process can consistently meet requirements at the customer’s demand rate. Automotive suppliers work under IATF 16949, whose 2016 edition folds many customer-specific requirements into one standard. Outside those two sectors there is no mandatory PPAP; the requirement comes from your own supplier-quality manual or purchase order.
That freedom is the opportunity. A heavy-equipment, pump or medical-device OEM can borrow the parts of PPAP that reduce its own risk and leave out the parts that only make sense inside an automotive program, such as customer-specific automotive portals or formats tied to a particular vehicle maker. The mistake is to copy the automotive requirement wholesale, pay for it in the piece price, and then never read most of what arrives.
Which PPAP elements matter for a cast and machined industrial part?
For a die-cast housing or a machined fitting, the elements that carry real information are the design record, the dimensional results, material and performance test records, the process flow, the process FMEA, the control plan and the measurement system studies. Design FMEA, appearance approval and master samples often do not apply to a build-to-print supplier.
| No. | Element | Suggested scope |
|---|---|---|
| 1 | Design records | Core: the released drawing and model, with the revision you are approving |
| 2 | Authorized engineering change documents | Core if any change is not yet on the drawing |
| 3 | Customer engineering approval | Only if your engineering team runs a separate sign-off |
| 4 | Design FMEA | Usually skip: the design FMEA belongs to whoever owns the design |
| 5 | Process flow diagram | Core: every operation from casting to packing, including outside finishing |
| 6 | Process FMEA | Core for parts with sealing, pressure or safety functions |
| 7 | Control plan | Core: what is checked, how, how often and what happens on a reject |
| 8 | Measurement system analysis | Core for gauges on critical characteristics only |
| 9 | Dimensional results | Core: full layout against a ballooned drawing |
| 10 | Material and performance test records | Core: alloy chemistry, coating results, leak or pressure tests if specified |
| 11 | Initial process studies | Only for characteristics you mark as critical |
| 12 | Qualified laboratory documentation | Ask for the scope and calibration evidence of the lab that ran the tests |
| 13 | Appearance approval report | Only for visible cosmetic surfaces |
| 14 | Sample production parts | Core: parts from the production run, identified by cavity or fixture |
| 15 | Master sample | Optional: useful when appearance or feel is hard to specify |
| 16 | Checking aids | List only, unless a custom fixture defines acceptance |
| 17 | Customer-specific requirements | Your own supplier-quality manual, if you have one |
| 18 | Part Submission Warrant | Core at every level |
Castings add two things a machined-from-bar part does not have. The first is cavity identity: a multi-cavity die is several processes sharing one press, so the dimensional results and samples should come from every cavity, marked as such. The second is internal soundness. If porosity matters on a sealing face, say how it is judged, by leak test, sectioning or radiography, and put that test in element 10; otherwise the dimensional layout will pass a part that leaks.
Machined features on a casting also need their datum scheme settled before the layout is run. When the drawing mixes as-cast and machined faces, mark which is which, so the results sheet compares each feature with the right tolerance class. Finishes belong in the same record: a coating thickness reading on the actual sample tells you more than a finish name on a certificate.
How do you scale PPAP down to a “PPAP-lite” pack?
Specify Level 4 on the purchase order and attach a one-page list of the records you want submitted, with the rest retained at the supplier. The list should follow the risk of the part, not the length of the manual.
A workable pack for a cast and machined industrial part usually contains the warrant, the ballooned drawing with full dimensional results, material and coating records, the process flow and a control plan. Add a process FMEA and capability studies only for the characteristics you flag as critical, and a gauge study only for the gauges that judge those characteristics.
When you do ask for capability, write the acceptance rule into the requirement rather than leaving it to habit. The AIAG manual treats a Ppk above 1.67 as meeting acceptance, 1.33 to 1.67 as possibly acceptable after discussion, and below 1.33 as not meeting it, and it describes the significant production run as 1 to 8 hours of production, at least 300 consecutive parts, unless the customer states otherwise. Those figures were set for automotive volumes. For a part ordered a few hundred at a time, state a smaller run and a sample size you can live with, or accept a full layout of several parts in place of a capability index.
For gauge studies, the AIAG MSA manual gives the familiar rule of thumb: a gauge R&R under 10% of tolerance is generally acceptable, 10% to 30% may be acceptable depending on the application, and over 30% is not. Ask for studies only where the tolerance is tight enough for the gauge to matter. A caliper check on a general-tolerance flange does not need one; an air gauge on a bearing bore does.
Finally, say what triggers a new submission. The AIAG manual requires a new PPAP for changes such as new tooling, a new material source or a move to a new plant location, and a short clause in your own requirements should list the same triggers, including a change of finishing subcontractor.
How is PPAP different from a first article inspection?
A first article inspection proves that one part from the production process meets the drawing; PPAP adds evidence that the process will keep meeting it. The first article is roughly one element of a PPAP, the dimensional results.
In aerospace the first article has its own standard, SAE AS9102C, revised in 2023, and AS9145 treats it as part of the wider approval. For many industrial buyers a good first article with material records is enough for low-risk parts, and the full approval package is worth its cost only on the parts that seal, carry load or define a fit in the assembly.
The difference shows up after the samples ship. A first article can be passed by one careful setup that production never repeats. A control plan, capability data on the critical features and a signed warrant give you something to hold the supplier to on the hundredth lot, which is why the extra records are worth paying for on the parts where a drift would be expensive.
What should you settle with an overseas supplier before asking for PPAP?
Agree the element list, the document language and format, and who approves the submission before tooling is released. A PPAP requested after the samples ship usually has to be rebuilt from records nobody kept.
When a part moves from China to Vietnam, or to any new source, the drawing stays the same but the plant, tooling, material mills and finishing lines all change. Each of those is a trigger for a new approval in its own right, so an old supplier’s PPAP proves nothing about the new one. Ask the new supplier to name every site that touches the part, including outside plating or anodizing, so the process flow you approve is the one you receive.
- Language and templates. Ask for English records, and supply your own warrant and control plan templates if you want a consistent format across suppliers.
- Material evidence. Name the certificate type you expect, such as an EN 10204 type 3.1 inspection certificate, and ask for alloy chemistry tied to the lot actually used.
- Laboratory evidence. For outside tests, ask for the lab’s accreditation scope, such as ISO/IEC 17025, and for calibration records. NIST’s policy is a useful reminder that each lab must support its own traceability claim; NIST does not certify it on the lab’s behalf.
- Remote review. If nobody can travel, agree a live video session during the layout of the critical features, then have the measured samples shipped with the package.
Be equally direct about the supplier’s quality system. Saola’s ISO 9001 certification is in progress and not yet held, and the quality page describes the first-article and inspection flow we run today; ask any new supplier for the same plain statement. For turned features, see CNC turning for what our lead CNC plant runs. If you have a part and an element list ready, send them with the RFQ so the approval package is scoped with the price instead of after it.
Frequently asked
Is PPAP mandatory for non-automotive parts?
No. Outside automotive it applies only when your purchase order or supplier-quality manual requires it, or when an aerospace customer flows down AS9145. You decide the level and the element list.
Can I ask for Level 3 but drop some elements?
You can, but it is cleaner to call it Level 4 and list what you want. That way the supplier and your own receiving inspection read the requirement the same way, and nobody argues later about which Level 3 records were waived.
Does a supplier need IATF 16949 to submit a PPAP?
No. The PPAP manual is a published procedure that any supplier can follow. IATF 16949 is a quality management system standard for automotive production; a non-automotive buyer can ask for a PPAP from a supplier that does not hold it.
Who owns the process FMEA and control plan?
The supplier writes and maintains them, because they describe the supplier’s process. You review and approve them as part of the submission, and you can require notice before they change.
Does PPAP cover every lot after approval?
No. PPAP approves the process once. Ongoing lots are governed by the control plan and your incoming inspection, and a new submission is due when a listed trigger, such as new tooling or a new site, occurs.
Sources
- Production Part Approval Process (PPAP), 4th edition, AIAG, 2006
- Measurement Systems Analysis (MSA), 4th edition, AIAG, 2010
- AS9145, Requirements for Advanced Product Quality Planning and Production Part Approval Process, SAE International, 2016
- AS9102C, First Article Inspection Requirements, SAE International, 2023
- IATF 16949:2016, about the standard, IATF, 2016
- ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories, ISO, 2017
- Metrological traceability policy, NIST, accessed September 2026
- EN 10204:2004, Metallic products — Types of inspection documents, CEN, 2004