The Zinc Plated Double End Stud Bolt (also known as an electro-galvanized double-end threaded stud, tap-end stud, or DIN 938/939 zinc-plated stud) is a high-precision, corrosion-resistant connection fastener featuring threaded profiles at both ends separated by an unthreaded center shank. Commonly threaded into cast iron or steel equipment housings at one end (tap end) and tightened with a hex nut at the other (nut end), this fastener is engineered for heavy machinery, valve flanges, engine blocks, and pressure vessels in compliance with global ISO standards.
Technical Specifications of Zinc Plated Double End Stud Bolt
We manufacture electro-zinc plated double end stud bolts in Class 4.8 low-carbon steel for standard structural connections and Grade 8.8 medium-carbon alloy steel for high-stress dynamic loads. Plated with an advanced trivalent chromium (Cr3+) zinc coating, the studs provide bright silver aesthetics and smooth thread engagement. Engagement lengths follow international standards: DIN 938 (~1d for steel housing), DIN 939 (~1.25d for cast iron housing), and DIN 835 (~2d for aluminum alloy housing).
| Parameter | Class 4.8 Zinc Plated Double End Stud | Grade 8.8 High Tensile Zinc Plated Stud |
|---|---|---|
| Core Material Grade | Low Carbon Steel (Q195 / Q235B) | Medium Carbon Steel (45#) / 40Cr Steel |
| Tensile Strength (Min) | 400 N/mm² (400 MPa) | 800 N/mm² (800 MPa) |
| Zinc Plating Layer | 5 µm – 12 µm Electro-Galvanized (Blue-White) | 5 µm – 15 µm (With Hydrogen Relief Baking) |
| Salt Spray Endurance | 48 Hours Neutral Salt Spray (NSS) | 72 – 96 Hours Neutral Salt Spray (NSS) |
| Tap End Length Options | DIN 938 (1d), DIN 939 (1.25d), DIN 835 (2d) | DIN 938 (1d), DIN 939 (1.25d), DIN 835 (2d) |
Forging and Electroplating Process for Double End Stud Bolt
At our manufacturing facility in Handan, China, electro-zinc plated double end stud bolts undergo high-precision cold forging, dual-end thread rolling, heat treatment, and automated barrel electroplating:
- Precision Shank Cutting & Forming: Carbon steel wire rods are cut to exact lengths with smooth center shank transitions to ensure balanced axial load distribution.
- Dual-End Precision Thread Rolling: Rolled metric 6g threads on both ends establish accurate pitch concentricity and fatigue resistance under cyclic vibration.
- Quenching & Tempering (For Grade 8.8): Controlled mesh-belt furnace heat treatment delivers a homogeneous martensitic structure with 800 MPa tensile strength.
- Electro-Zinc Plating & De-Embrittlement: Acid pickling removes surface mill scale, followed by galvanic zinc deposition, Cr3+ blue-white passivation, and thermal baking to eliminate hydrogen embrittlement risks.
Industrial Applications of Zinc Plated Double End Stud Bolt
Zinc-plated double-end stud bolts are specified in engineering assemblies requiring clean appearance and frequent disassembly without damaging female threads in expensive equipment:
- Pumps, Valves & Pipe Flanges: Fastening water supply pipeline flanges, pump casings, and industrial valve covers where one end remains permanently anchored into the valve body.
- Automotive Engine Blocks & Transmission Housings: Securing cylinder heads, exhaust manifolds, and gearbox assemblies.
- Heavy Industrial Machinery & Gearboxes: Fastening reducer gearboxes, hydraulic equipment bases, and industrial press frames.
Quality Control and Export Packaging for Zinc Plated Double End Stud Bolt
Handan YiHao Fastener enforces comprehensive Quality Assurance (QA) protocols for all overseas export orders. Inspection procedures include dual-end thread ring gauge pass/fail tests, zinc coating thickness gauge verification, neutral salt spray validation, and tensile strength testing.
All export items are packed in heavy-duty 25kg inner cartons, neatly stacked on ISPM 15 compliant fumigated wooden pallets, and wrapped in protective stretch film to ensure safe maritime freight.
Request Factory Direct Pricing for Zinc Plated Double End Stud Bolts
Looking for a trusted manufacturer in Handan, China for Class 4.8 or Grade 8.8 electro-zinc plated double end stud bolts (DIN 938 / DIN 939 / GB 898)? Contact Handan YiHao Fastener today for technical datasheets, custom tap-end lengths, matching zinc-plated hex nuts, and direct bulk export quotes.
