Small-part finishing for factories in Rojana Chonburi (Bowin)
This estate’s two leading trades pull a fastener in different directions. One sends parts into a vehicle, where they live warm, dry and hidden. The other sends parts into a frame that stands outside in coastal air for the design life of the array. The second is the harder corrosion problem, and it is the one most drawings under-specify.
We run one plant, and it is in Samut Sakhon. This page covers collection and delivery for customers in Chon Buri — it is not a branch or a facility in Chon Buri.
This estate at a glance
| Province | Chon Buri |
|---|---|
| Road corridor | Highway 331 — Eastern Seaboard |
| Nearest sea port | Laem Chabang Port |
| IEAT-designated | Yes |
| Eastern Economic Corridor | Yes |
| Industry mix | automotive & parts, electronics |
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
First, which Rojana this is. The group runs several estates, and more than one of them is in Chonburi — a buyer who types the name alone could mean any of them, or the Ayutthaya park up north. This page is the Bo Win one, the park the operator itself calls Chonburi 1: an estate designated under the Industrial Estate Authority of Thailand and run jointly with a private developer, in Bo Win subdistrict, Si Racha district, adjoining Highway 331. Chonburi is one of the three provinces inside the Eastern Special Development Zone, so this estate sits in the EEC as a matter of law rather than of marketing — the Ayutthaya park does not. The operator’s own record for this park puts two trades in front: automotive-related manufacture, and solar-panel manufacture. That second one is why this page reads nothing like the Ayutthaya one.
What this estate asks of a small part
Solar hardware is the part of this estate’s mix that changes how we quote. A plated steel bolt clamped into an aluminium extrusion is a dissimilar-metal joint that will sit outdoors, in coastal air, for decades — and what decides whether it survives is the coating system, not the tensile class. Two numbers on the drawing do most of the work and are constantly confused: hours of neutral salt spray to white corrosion of the coating, and hours to red rust of the base steel. They are different requirements, they are met by different means, and a drawing that gives one number and no label cannot be quoted honestly. Send both, plus the passivate class you need, and we will tell you what an electroplated zinc coating with Cr3+ passivation can and cannot reach — including the case where the answer is that it cannot. A structural mounting rail specified for a multi-decade outdoor life usually belongs in hot-dip galvanizing or a duplex system, and hot dip is not a process we run: we electroplate small parts in bulk, and we would rather say that at quotation than take the lot. The automotive side of the estate is the more familiar work — a property class held to ISO 898-1, hardness inside a band, and a hydrogen de-embrittlement bake once the strength and coating combination crosses the ISO 4042 trigger — but the two specifications stay separate on paper and separate in the records.
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.
The corridor row on this page names Highway 331, the inland Eastern Seaboard route, because the operator’s own record for this park puts the estate on it — not because 331 is the highway that happens to run through the province. The port row names Laem Chabang, and here nearest and actual are the same answer for once: the estate and the container port are in the same district, so parts finished for this estate are more often headed for a container than for a domestic assembly line. That is worth planning for. A lot leaves a plating line clean and then waits — in your warehouse, in a box, in a stuffed container — and bright zinc with a thin passivate and no sealer will bloom while it waits, which the receiving inspection at the far end will read as a plating fault. Tell us the part is going to sea and we will confirm the passivate and note it on the lot record. Collection and delivery are arranged per lot with sales; nothing on this page is a transit time or a completion-date promise.
Questions we get from this estate
Our solar mounting hardware is a plated steel bolt into an aluminium frame. Will zinc plating survive outdoors?+
It depends entirely on what the drawing asks for, which is why we need the numbers rather than the intent. Zinc is sacrificial to steel, so the coating corrodes first and the bolt keeps its strength while the coating lasts — the question is only how long that is. Give us hours of neutral salt spray to white corrosion and hours to red rust as two separate figures, plus the passivate class, and we will tell you whether an electroplated zinc coating with Cr3+ passivation reaches them. If the requirement is a structural part with a multi-decade outdoor life, the honest answer is often hot-dip galvanizing or a duplex system instead — that is a different trade, we do not run it, and we will say so at quotation rather than plate the part and hope.
There are several Rojana estates. Is this page about ours?+
This page is about the Bo Win park in Si Racha district, Chonburi — the one the operator calls Chonburi 1, on Highway 331. Rojana runs other estates in this province and others outside it, including the Ayutthaya park many people mean when they type the name alone. Practically, the estate you sit in does not change how a part is processed: your drawing does. It changes which page describes your neighbours, and which port your finished lot is likely to leave through.
Our zinc-plated parts go into a container at Laem Chabang and arrive with white bloom. What can we change?+
Usually the passivate and the packing, not the zinc thickness — adding microns to a coating that is blooming in a humid box does not fix the mechanism. Tell us the lot is going to sea and whether a sealer is permitted by your customer’s specification, and we will confirm the passivate type against that document and record what was applied on the lot. What we cannot control is how long the container sits and what it is packed with, so it is worth agreeing the packing at the same time as the finish.