Small-part finishing for factories in Rojana Industrial Park
Rojana carries automotive and electronics on the same estate — two industries whose fastener specifications barely overlap. Sending both to one finisher works only if the finisher keeps them apart.
We run one plant, and it is in Samut Sakhon. This page covers collection and delivery for customers in Phra Nakhon Si Ayutthaya — it is not a branch or a facility in Phra Nakhon Si Ayutthaya.
This estate at a glance
| Province | Phra Nakhon Si Ayutthaya |
|---|---|
| Road corridor | Highway 309 (Rojana Road) |
| Nearest sea port | Bangkok Port (Khlong Toei) |
| IEAT-designated | Yes |
| Eastern Economic Corridor | No |
| Industry mix | automotive & parts, electronics, general manufacturing & SMEs |
IEAT-designated covers both estates operated by the Industrial Estate Authority of Thailand and joint-operation estates run with a private developer. A dash means we could not confirm a single status for the whole area — some of these names describe a factory district rather than one designated estate.
A dash in the port row means the estate sits inland between two ports and we will not guess which is nearer. Nothing on this page is a distance, a drive time or a delivery-time promise.
Reviewed:
What this estate is
Rojana is an IEAT joint-operation estate on Highway 309 in Ayutthaya, north of Bangkok, with automotive, electronics and general manufacturing side by side. That combination is what makes it distinctive: an automotive fastener from this estate is a strength part with a property class and a mandatory bake, while an electronics screw from the same estate is a thin, cosmetic, appearance-critical part where the plating thickness is limited by the thread fit. Neither specification is a relaxed version of the other.
What this estate asks of a small part
The two spec worlds pull the same process in opposite directions. Automotive asks for hardness held in a band, hundreds of hours of salt-spray resistance and de-embrittlement baking once the ISO 4042 trigger is crossed. Electronics asks for a thin, even, cosmetically clean deposit that still lets the thread assemble, and often for restricted-substance compliance rather than raw strength. We keep them as separate specifications with separate records rather than averaging them into a house standard — and if a drawing tries to ask for both at once, we say so before processing.
Services for factories in this estate
Hardening, Cr3+ zinc plating, phosphate coating and in-house lab testing, all on small parts at bulk volume.
Steel grades behind those parts
End markets on this estate
Each end market has its own spec drivers — property classes, salt-spray hours, governing standards.
Rojana takes Highway 309, connecting to the Asian Highway for the run south, and the nearest sea port by geography is Bangkok Port at Khlong Toei. Parts reach our Samut Sakhon plant via the western ring and the Rama II corridor. Collection and delivery are arranged per lot with sales; nothing on this page is a transit-time or completion-date promise.
Questions we get from this estate
Can one plating line serve both our automotive and our electronics parts?+
The line can; one specification cannot. Automotive parts are usually thicker-plated, baked and tested for hardness and salt spray, while electronics screws are thinner, appearance-graded and limited by thread fit. Send them as separate part numbers with separate drawings and they come back with separate records — which is also what your auditor expects to see.
How thick can the zinc be before the thread stops fitting?+
That is set by the thread tolerance on your drawing, not by the plating shop. ISO 4042 covers how coating thickness is allowed for on threaded parts, and the practical limit falls as the thread gets finer. Give us the thread designation and the tolerance class and we will tell you what thickness the fit will accept.