Thailand has a deep automotive supply base, and finding a factory that can make a stamped bracket, a machined housing or a moulded clip is rarely the hard part. Projects stall at a different point: the quotation comes back with assumptions you never made, the first samples are dimensionally fine but fail a requirement that was never on the drawing, or the approval documents arrive in a form your customer will not accept. All three trace back to what was sent with the request for quotation.
💬 Moving a part to a Thai manufacturer, or adding Thailand as a second source? For each project we find, vet and manage the factory that fits the part, and run the drawing and document questions with it. See sourcing from across Asia, or send us the drawing and annual volume. How we work there: our sourcing agent service for Thailand.
How to find Thai suppliers, check them in the business registry and obtain a certificate of origin is covered in our buyer’s guide to sourcing from Thailand and finding factories across ASEAN. This article is about the engineering and quality paperwork between you and the factory.
What a Thai factory needs before it can quote properly
A factory can only quote what is defined, so send a drawing package that answers material, tolerance, surface treatment, special characteristics, revision and packaging before you ask for a price.
A quotation is the factory’s reading of your drawing. Where the drawing is silent, the factory fills the gap with its own assumption, usually the one that is cheapest to make. When you later correct the assumption, the price changes and the comparison you made between suppliers is no longer valid.
| Drawing gap | What the factory has to guess | What to send instead |
|---|---|---|
| No general tolerance note, or a note that cites no standard | How tight the untoleranced dimensions must be | A general tolerance note that cites the standard and class you use (for example ISO 2768 or JIS B 0405) |
| Material named only by one country’s grade | Which local equivalent is acceptable, and whether a mill certificate is needed | The grade, the acceptable equivalents you have approved, and the certificate you expect |
| ”Zinc plated” or “painted” with no specification | Coating type, thickness, corrosion test and appearance standard | The coating specification, the test method and the acceptance criterion your customer uses |
| 2D drawing and 3D model that disagree | Which one governs | A statement of which document governs, and the revision of each |
| Critical or safety features not marked | Which characteristics need tighter process control | Special characteristics marked on the drawing with your customer’s symbols |
| No revision control | Whether the drawing in hand is current | A revision level on every sheet and a rule for notifying changes |
| No packaging or rust-prevention requirement | How the part survives sea freight and storage | Packing method, rust prevention and labelling per carton |
None of these needs a number invented by the buyer. They need the numbers your own customer already holds, passed on in full. If you do not have them, that is the first thing to resolve, before any factory is asked to quote.
Annual volume, the expected life of the programme and the number of variants also change the quotation, because they decide whether the factory proposes dedicated tooling. If dedicated tooling is proposed, agree in writing who pays for it, who owns it, where it is kept, and on what terms it can be moved.
IATF 16949: what the certificate tells you, and what it does not
IATF 16949 is the automotive quality management standard, and a certificate is worth checking for the exact site and scope, but it does not replace your own approval of the part.
IATF 16949:2016 replaced ISO/TS 16949:2009 and is maintained by the International Automotive Task Force, which keeps it aligned with ISO 9001. The IATF provides a certificate validity check through its customer portal. Use it, rather than relying on a scanned certificate.
When you read a certificate, check three things:
- The site. A certificate covers named sites. A group with several plants may hold it for one and propose to make your part at another.
- The scope. The certificate describes the products or processes covered. A plant certified for machining is not thereby certified for the plating it subcontracts.
- Whether your customer requires it. Some automotive customers require certification of their direct suppliers; parts going into the aftermarket or into non-automotive uses may not. Ask your customer, and put the answer in the specification.
A factory without the certificate can still be the right choice for some parts. The question is whether it can produce the documents your customer will ask for, which is the subject of the next section.
Checked against the International Automotive Task Force’s published page on IATF 16949:2016 on 17 October 2026.
💬 Not sure whether your customer needs an IATF-certified source, or which approval documents they will expect? We clarify this with you before the request for quotation goes out. Tell us who the part is for.
PPAP: decide the submission level and the format before the first sample
The production part approval process (PPAP) is the automotive industry’s standard way of approving a part made on production tooling and processes, and the customer, not the supplier, decides which submission level and format applies.
PPAP is defined in a manual published by the Automotive Industry Action Group (AIAG). It lists the documents and samples a supplier may have to submit, with a Part Submission Warrant as the cover document, and sets out submission levels that range from a warrant alone to a full package reviewed at the supplier’s site. Several vehicle makers use their own formats or phased versions of the process.
The practical point for a buyer placing work in Thailand is to fix three things before the first production-intent sample:
- The level. Ask your customer which level applies to this part. If you are the customer, decide it and say so in the purchase order.
- The format. Your customer’s own forms, or the standard forms. A full set prepared in the wrong format is redone.
- The language and units. Agree that documents are in English and in the units used on the drawing.
The documents most often requested, and what they tell you:
| Document | What it shows | What to check |
|---|---|---|
| Design records and engineering change documents | The drawing revision the samples were made to | The revision matches your current drawing |
| Process flow diagram | Every step from raw material to packing, including subcontracted steps | Outside processes such as plating or heat treatment are shown, with the subcontractor named |
| Process FMEA | How the factory has assessed what could go wrong at each step | The special characteristics on your drawing appear and are addressed |
| Control plan | How each characteristic is controlled and checked in production | Frequency and method are stated for each special characteristic |
| Dimensional results | Measurements of samples against every drawing dimension | Every dimension is reported, not a selection |
| Material and performance test results | Certificates and test reports | Tests are by the method your specification names |
| Measurement system analysis | Whether the gauges can measure what the drawing requires | The gauges used match those named in the control plan |
| Part Submission Warrant | The supplier’s declaration that the submission conforms | Signed, and referencing the correct revision |
How to approve samples in stages, and what to freeze at each stage, is covered in sample approval stages. The same staging works for a Thai automotive part, with the PPAP package as the final stage.
TISI: when a Thai standard applies to the part
Some vehicle parts fall under Thailand’s compulsory industrial standards, which govern manufacture for sale in Thailand, and the Industrial Product Standards Act has a separate route for making such products to a foreign standard for export.
The Thai Industrial Standards Institute (TISI) runs both voluntary and compulsory standards; the general picture is in our Thailand buyer’s guide. For contract manufacturing, the points that matter are these:
- Under the Industrial Product Standards Act B.E. 2511 (1968), Section 20, a person who manufactures a product that must conform to a compulsory standard needs a licence after inspection.
- Section 20 bis allows the Minister, for the benefit of export, to permit a licensee to make such products to a foreign or international standard approved by the standards council, which may be higher or lower than the Thai standard.
So if your part is on TISI’s compulsory list and is made to your customer’s foreign standard for export, ask the factory two questions: does it hold the TISI licence for that standard, and does this order need permission under the export provision? If the part is not on the compulsory list, neither question arises.
Checked against the text of the Industrial Product Standards Act published on WIPO Lex on 17 October 2026. The Act has been amended several times, so confirm the current text and TISI’s current compulsory list for your part before you rely on this.
Inspection, shipment and the first year
Agree how lots are inspected, packed and labelled before the first shipment, and treat the first months of supply as a period of closer control, not as approval complete.
The PPAP package approves a process at one moment. After that, three habits keep a Thai source stable:
- A change notification rule. The factory tells you before it changes material, subcontractor, site, tooling or process, not after. Put this in the quality agreement.
- Lot inspection with clear criteria. Decide whether you inspect before shipment, and on what sampling basis; our note on pre-shipment inspection and AQL sets out the method.
- Traceable labelling. Each carton carries part number, revision, lot and quantity, so a problem found at your customer can be traced to a production date.
Origin paperwork for a preferential duty rate goes through Thailand’s Department of Foreign Trade; which agreement to use for Japan is covered in EPA or RCEP for imports from Thailand. For comparing a Thai quotation with others in the region on the same basis, see comparing Asian quotations on landed cost. Car accessories such as visors, mats and seat covers, which follow a different, fit-led route, are covered in car accessory OEM in Taiwan, Thailand and Malaysia.
💬 Want the drawing package, approval documents and inspection plan agreed before you commit to a Thai factory? We run this for parts projects in Thailand and across Asia. Send us the drawing.
Frequently asked questions
1. Does a Thai supplier need IATF 16949 to make automotive parts for me?
Not always. It depends on what your customer requires. Where certification is required, check the certificate for the exact site and scope through the IATF’s certificate validity check.
2. Who decides the PPAP submission level?
The customer. The AIAG manual sets out the levels, and the customer chooses the level and format for each part. If you are the customer, state it in the purchase order.
3. What should I send with a request for quotation?
A drawing package with a general tolerance note, material grade and acceptable equivalents, coating specification, marked special characteristics, a revision level and packaging requirements, plus annual volume and programme life.
4. Does a part made in Thailand for export need a TISI licence?
Only if the part falls under a compulsory standard. The Industrial Product Standards Act also allows a licensee to make such products to a foreign standard for export with permission. Confirm the current list and text with TISI for your part.
5. Who owns the tooling for my part?
Whoever the agreement says. Agree in writing who pays for dedicated tooling, who owns it, where it is kept and how it can be moved, before tooling is ordered.
Sources: International Automotive Task Force, IATF 16949:2016 overview and certificate validity check (iatfglobaloversight.org); Automotive Industry Action Group, Production Part Approval Process manual (as referenced in supplier quality manuals); Industrial Product Standards Act B.E. 2511 (1968), Sections 20 and 20 bis, as published on WIPO Lex; Thai Industrial Standards Institute (tisi.go.th). Checked on 17 October 2026.