Slotted Countersunk Head Bolt & 8 Galvanized Carriage Bolts | Maker
Slotted Countersunk Head Bolt & 8 Galvanized Carriage Bolts | Maker
Slotted Countersunk Head Bolt & 8 Galvanized Carriage Bolts with Nuts and Washers — Factory-Direct Maker
⚙️ Engineered for flush-mount precision and corrosion-resistant structural joining — ISO 9001 quality, 30+ country exports, and 30% lower TCO vs. Western distributors.
Trusted by procurement teams in automotive, construction, and agricultural machinery across Europe & North America.
⚠️ The Hidden Cost of Sourcing slotted countersunk head bolt & carriage bolts from the wrong supplier
Price volatility & hidden fees
Spot-market pricing for 8 galvanized carriage bolts with nuts and washers can swing 15-25% quarterly. Add freight surcharges, and your landed cost becomes unpredictable.
Inconsistent quality & reject rates
A major agricultural OEM reported 12% rejection on imported carriage bolts due to off-spec square neck dimensions. Downtime cost: €4,200 per hour.
Ocean freight & lead time risk
Container shipping from Asia to Rotterdam or Los Angeles still averages 35-45 days. One delay can stall your entire production line.
Compliance & documentation gaps
Missing CE marking or incorrect material certs can block customs. 37% of importers faced delayed clearance in 2025 due to non-compliant fasteners (source: EC import audit).
Limited customization & technical support
Most traders can't modify head height, thread length, or plating thickness. You need a maker who understands your engineering drawings.
Total cost of ownership (TCO) blind spot
Low unit price + high reject rate + expedited freight + admin overhead = up to 40% higher TCO than a stable, certified factory partner.
🔍 You're not alone. 73% of procurement managers say fastener quality and supply stability are their top two concerns for 2026. See how Boen solves this →
✅ Boen Precision Fastener Solution — slotted countersunk head bolt & carriage bolts engineered for industrial performance
Factory-Direct slotted countersunk head bolt
Produced on CNC cold-forging lines with in-house heat treatment. DIN 963 / ISO 2009 compliant. Flush-fit countersink angle: 90° ±1° for clean, snag-free assemblies.
- M3 – M20 diameter range
- Grades 4.8, 8.8, 10.9, A2-70, A4-80
- Zinc plated, HDG, or black oxide
- 0.8 μm Ra surface finish option
8 Galvanized Carriage Bolts with Nuts and Washers
Complete ready-to-install kit. Hot-dip galvanized (HDG) per ASTM A153. Square neck fully formed to prevent spin-out during tightening. Salt spray resistance: 500+ hours.
- 1/4″ – 3/4″ diameter (or metric M6–M16)
- Lengths: 1″ – 8″ (custom up to 12″)
- Includes class 8.8 hex nut & flat washer
- Tested to ASTM F568M standard
High-Speed Delivery & Supply Stability
Our 3-week lead time for standard sizes beats the industry average by 40%. Dedicated buffer stock for high-volume SKUs ensures 98% on-time dispatch.
- 20-ft container: 15–18 working days
- Express LCL: 10–12 working days
- ERP integration: EDI, CSV, or API
- Free sample for pre-production approval
📊 Technical Specifications — slotted countersunk head bolt & 8 galvanized carriage bolts
| Parameter | Slotted Countersunk Head Bolt | 8 Galvanized Carriage Bolts (Kit) |
|---|---|---|
| Standard | DIN 963 / ISO 2009 | DIN 603 / ASTM A307 Grade A |
| Material | Carbon steel, stainless steel 304/316, brass | Carbon steel, hot-dip galvanized (HDG) |
| Grade | 4.8 / 8.8 / 10.9 / A2-70 / A4-80 | 4.6 / 8.8 (nut: class 8) |
| Diameter range | M3 – M20 (inch: #6 – 3/4″) | M6 – M16 (1/4″ – 5/8″) |
| Length range | 8 mm – 200 mm (custom up to 300 mm) | 25 mm – 200 mm (1″ – 8″) |
| Head angle | 90° ±1° (countersink) | Domed head, square neck (10 mm × 10 mm) |
| Plating / coating | Zinc, HDG, black oxide, Dacromet, passivated | Hot-dip galvanized (≥ 50 μm) |
| Corrosion resistance | Salt spray 72–500 h (depending on coating) | Salt spray ≥ 500 h |
| Tensile strength | 400 – 1200 MPa (grade dependent) | 400 – 800 MPa |
| Packaging | Bulk 25 kg cartons, small boxes, or poly bags | Kit: 8 bolts + 8 nuts + 8 washers per poly bag |
*Custom sizes, materials, and packaging available upon request. Contact our engineering team for OEM/ODM projects.
Agricultural machinery
Carriage bolts for harvester tines, slotted countersunk bolts for panel mounting. Used by 3 major European OEMs.
Construction & structural steel
Flush-fit bolts for handrails, scaffolding, and steel frame connections. CE marked for construction.
Automotive & trailer manufacturing
Countersunk bolts for floor panels, carriage bolts for chassis assemblies. IATF 16949 aligned process.
Renewable energy (solar/wind)
Corrosion-resistant fasteners for solar tracker structures and wind turbine towers. 25-year durability target.
❓ Frequently Asked Questions — slotted countersunk head bolt & carriage bolts
A: Standard sizes (M6–M16, 1″–6″) ship in 15–18 working days for a full 20-ft container. Express LCL orders available in 10–12 days. We also keep buffer stock for repeat orders.
A: Yes. Our toolroom can modify head angle (60°–120°), slot width/depth, and underhead radius. Send your drawing or sample for a free engineering review.
A: All fasteners are manufactured under ISO 9001:2015. We provide CE, RoHS, FCC, and UL certifications where applicable. Material test reports (MTR) and batch traceability included.
A: Absolutely. We provide free samples (you pay shipping). Sample lead time: 3–5 working days. Pre-production samples (PPAP) available for approval before mass production.
A: MOQ for standard sizes: 5,000 pcs per size. For custom dimensions or special materials, MOQ starts at 2,000 pcs. We can also accommodate trial orders of 1,000 pcs for new customers.
A: We follow ASTM A153 / ISO 1461 for hot-dip galvanizing. In-house testing includes coating thickness gauge, salt spray chamber, and adhesion bend test. Certificates issued batch-wise.
A: We accept T/T (30% deposit, 70% before shipment), L/C at sight, and for established customers — net 30 days (subject to credit approval). We also support Alibaba Trade Assurance.
A: Yes. Our engineering team offers free technical consultation on fastener selection, torque values, and installation. We also provide installation guides and video support for large projects.
⭐ Real Reviews from Buyers Across the Globe
“We use Boen's slotted countersunk head bolts for our bridge railing systems. The consistency of the 90° countersink is remarkable — no more sanding down proud heads. Installation time reduced by 18%.”
★★★★★
“Ordered 8 galvanized carriage bolts with nuts and washers for our turbine tower assembly. The HDG coating passed our 600-hour salt spray test. Delivery was 3 days ahead of schedule.”
★★★★★
“Boen helped us consolidate 4 fastener suppliers into 1. Their OEM design support for a custom carriage bolt saved us €0.12 per unit — €18,000 annual savings. Excellent communication throughout.”
★★★★★
Ready to Secure Factory-Direct Pricing on Your Next Fastener Order?
✅ Free samples for pre-production approval
✅ 15–18 day lead time for standard slotted countersunk head bolt & 8 galvanized carriage bolts with nuts and washers
✅ ISO 9001 · CE · RoHS — full documentation included
✅ 30-day money-back guarantee on first order if not satisfied
Or email us directly: shuan@fastenboen.com · mary@fastenboen.com · grace@fastenboen.com · stella@fastenboen.com
📍 Hanguang Industrial Park, Yongnian District, Handan City, Hebei Province, China · Mon–Fri 09:00–17:00
🏭 Factory Strength & Global Trust — Boen Fasteners
Trusted by procurement teams at:
We switched to Boen for our 8 galvanized carriage bolts with nuts and washers. Reject rate dropped from 9% to 0.3%. Saved us €28,000 in the first year.
The slotted countersunk head bolt quality from Boen is outstanding. Consistent 90° head angle, clean slots, and the zinc plating is flawless. We now use them for all our control panels.
Boen's factory-direct pricing and fast delivery transformed our supply chain. We reduced inventory by 30% while improving line fill rate to 99%.