Inside Our Factory
Fastener quality is decided before the first thread is rolled. This page shows what actually happens to your order between the steel coil and the container.
Production flow — what happens to your order
Raw material
Steel coil arrives with mill certificates. We verify chemistry and diameter on arrival, and keep heat numbers on file so a finished bolt can be traced back to the coil it was made from.
Cold heading
Multi-station cold headers form the head and shank in a single pass at room temperature. Cold forming refines the grain flow around the head fillet, which is where bolts usually fail — a cut head simply cannot match it.
Thread rolling
Threads are rolled between flat or cylindrical dies rather than cut. Rolling displaces metal instead of removing it, so the thread is stronger and the roots are work-hardened. Threads are gauged with GO/NO-GO plugs and rings.
Heat treatment
For grade 8.8, 10.9 and 12.9, parts run through a continuous mesh-belt furnace with controlled quench and temper, then hardness tested. Temperature curves are recorded per batch.
Surface finish
Zinc plating, hot dip galvanizing, black oxide, phosphating and Dacromet coating. Coating thickness is measured and salt spray tested according to the hours your market requires.
Inspection & packing
Final dimensional, hardness, thread and visual inspection. Then bulk cartons, colour boxes or OEM printed packaging, with pallet marking to your instruction.
Equipment and capacity
| Equipment | Quantity | Capability |
|---|---|---|
| Cold heading machines | 32 sets | Two-, three- and four-station headers, M3 to M24, up to 180 pieces per minute on small sizes |
| Thread rolling machines | 20 sets | Flat die and cylindrical die, metric / UNC / UNF / BSW, with automatic thread gauging |
| Heat treatment lines | 2 lines | Continuous mesh-belt furnace with controlled atmosphere, quench and temper, for grade 8.8 to 12.9 |
| Surface treatment | Plating + HDG | Barrel and rack zinc plating, hot dip galvanizing, black oxide and phosphating |
| Inspection equipment | Full set | Tensile tester, hardness tester (HRC / HV), salt spray chamber, optical projector, thread gauges, torque tester |
| Packing capacity | In-house | Automatic weighing and counting, colour box forming, barcode labelling and OEM carton printing |
Capacity at a glance
Yongnian runs one of the densest logistics networks in northern China, with more than 50 freight stations and over 5,000 large trucks. Goods move from our workshop to Tianjin, Qingdao or Shanghai port within a day, which is why we can hold a 15-day lead time on standard items. Air freight, express and rail (China–Europe) are also available for urgent or sample shipments.
Packing options
- Bulk: 25 kg carton, 36 cartons per pallet, shrink wrapped and strapped
- Small box: 100 / 200 / 500 pcs per box, then into export carton
- OEM: colour box, printed carton, barcode and pallet label to your artwork
- Container loading: palletised or floor loaded, mixed items consolidated on request
Want to see the workshop on video?
Message us on WhatsApp and we will send a live walk-through of the line that will run your order.
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