RAYCHIN LIMITED, we are materials experts who focus only on fasteners made from the highest performance specialty metals for the most challenging and extreme applications.

• Stainless Steel Series: Martensitic Stainless Steel, Ferritic Stainless Steel, Austenitic Stainless Steel, Austenitic-Ferritic (Duplex) Stainless Steel and Precipitation Hardening Stainless Steel.

• Super Alloys Series: Nickel-based Alloy, Cobalt-based Alloy, Iron-based Alloy, Molybdenum-based Alloy, ‌Titanium-based Alloy, Copper based Alloy, ‌Zirconium Alloy.

• Alloy Steel Series: Low Alloy Steel, Medium Alloy Steel, High Alloy Steel, Special Alloy Steel.

Countersunk Bolts | Flat Head & Socket Countersunk Screws in Special Alloys | RAYCHIN Manufacturer

RAYCHIN manufactures countersunk bolts in 25+ alloys including A286, MP35N, Titanium & Hastelloy. Flat head screws, countersunk socket screws & custom flush fasteners compliant with ASME, DIN, ISO, NASM standards. Global supplier for aerospace, marine & precision engineering.

Countersunk Bolts for Flush-Mount & Aerodynamic Applications

RAYCHIN is a precision manufacturer of high-performance countersunk bolts (also called flat head bolts, countersunk screws, or flush head bolts)—specialized fasteners designed with a conical head that sits perfectly flush with or below the mounting surface when installed in a countersunk hole. These fasteners are essential for applications requiring aerodynamic surfaces, smooth finishes, safety in moving parts, and clean aesthetic lines. We engineer these critical components from over 25 advanced alloys to meet stringent requirements in aerospace, marine, precision machinery, medical devices, and transportation industries worldwide.

Countersunk Bolt Types & Classifications

We manufacture comprehensive countersunk bolt configurations to address diverse technical requirements:

1. Standard Countersunk Bolts:

• Flat Head Countersunk Bolts: Traditional 82° or 90° included angle head with slotted drive, manufactured to ASME B18.6.2, DIN 963, ISO 2009, and JIS B1109 standards.

• Countersunk Socket Head Cap Screws: Feature internal hex drive (Allen) for streamlined appearance, compliant with ASME B18.3, DIN 7991, ISO 10642, and NASM 21250 specifications.

• Oval Head Countersunk Bolts: Rounded top surface with countersunk underside for decorative applications per DIN 964 and ISO 2010.

2. Special Application Countersunk Bolts:

• 100° Countersunk Head Bolts: Specialized head angle for aerospace and racing applications, meeting NASM 21250 and MS 24693 standards.

• Countersunk Shoulder Bolts: Combine flush head with precision shoulder for alignment in confined spaces.

• Countersunk Structural Bolts: High-strength bolts for airframe assembly and structural connections.

• Custom Countersunk Designs: Manufactured to exact OEM specifications with unique head angles, drive types, and special features.

Material Grades & International Standard Specifications

Our countersunk bolts are precision-machined from the following advanced material systems with full international standard compliance:

1. Precipitation-Hardening Stainless Steels:

• 17-4 PH (UNS S17400): Supplied to ASTM A564 Type 630, AMS 5643, DIN 1.4542 in H900, H1025, H1150 tempers for high-strength aerospace countersunk bolts.

• PH 13-8 Mo (UNS S13800): Manufactured per ASTM A564 Type 625, AMS 5629 for superior strength-toughness combination.

2. Nickel-Based Superalloys:

• Inconel® Alloys: Inconel 718 (UNS N07718/AMS 5663), Inconel 625 (UNS N06625/ASTM B446), Inconel 600 (UNS N06600) for high-temperature turbine casing bolts.

• Monel® Alloys: Monel K500 (UNS N05500/AMS 4676), Monel 400 (UNS N04400) for marine decking and offshore flush fasteners.

• Hastelloy® Alloys: Hastelloy C276 (UNS N10276/ASTM B574), C22 (UNS N06022), B2 (UNS N10665) for severe chemical processing environments.

• Waspaloy (UNS N07001): Per AMS 5708, AMS 5824 for high-temperature aerospace applications.

• Nimonic® Series: Nimonic 80A (UNS N07080), Nimonic 90 (UNS N07090) compliant with BS HR 501/502 standards.

3. Duplex & Super Duplex Stainless Steels:

• Duplex Steel: Duplex 2205 (UNS S32205) to ASTM A193 B8S, EN 1.4462 specifications for marine hardware countersunk bolts.

• Super Duplex Alloys: Alloy 926 (UNS N08926), AL-6XN® (UNS N08367) meeting ASTM A193 B8S, NACE MR0175.

4. Titanium Alloys:

• Grade 5 Titanium (Ti-6Al-4V): UNS R56400 per AMS 4928, ASTM F467 for lightweight aircraft skin fasteners.

• Grade 2 Titanium: UNS R50400 to ASTM B348, AMS 4921 for marine grade countersunk bolts.

5. Refractory & Exotic Metals:

• Tantalum (UNS R05200): ASTM B365, AMS 7845 for chemical equipment flush fasteners.

• Zirconium 702 (UNS R60702): ASTM B550, ASME SB550 for acid applications.

• Molybdenum (UNS R03600) & Tungsten: For extreme temperature applications.

6. Specialty Alloys:

• Nitronic® Alloys: Nitronic 60 (UNS S21800), Nitronic 50 (UNS S20910) to ASTM A193 B8N for high-strength applications.

• High-Performance Stainless: 254 SMO (UNS S31254/EN 1.4547), 310SS (UNS S31000), Alloy 20 (UNS N08020), Alloy 330 (UNS N08330).

• Cobalt Alloys: MP35N (UNS R30035/AMS 5844), MP159 (AMS 5846) for ultra-high strength countersunk fasteners.

• Iron-Based Superalloy: A286 (UNS S66286) to AMS 5731, ASTM A453 Grade 660.

7. Aluminum Alloy:

• Aluminum 7075 (UNS A97075): AMS QQ-A-225/9, ASTM F467 in T6, T73 tempers for lightweight aerospace flush fasteners.

8. Pure Nickel & Incoloy:

• Nickel 200 (UNS N02200): ASTM B160, ASME SB160.

• Incoloy® Alloys: Incoloy 825 (UNS N08825), Incoloy 925 (UNS N09925).

Custom Countersunk Bolt Manufacturing Services

RAYCHIN provides complete custom countersunk bolt manufacturing from your technical specifications:

• Standards Compliance: ASME B18.6.2, DIN 963, ISO 10642, NASM 21250, MS 24693, and customer drawings.

• Precision Tolerances: Head angles held to ±0.5°, flushness tolerance ±0.05mm, concentricity within 0.025mm.

• Special Features: Reduced head height, special drive systems, thread-locking features, sealing elements, heat-treated sections.

• Surface Finishes: Mechanical polishing, electropolishing, passivation, special coatings.

• Full Processing: CNC machining, cold heading, thread grinding, heat treatment, surface finishing.

• Quality Assurance: Complete MTRs (EN 10204 3.1), dimensional verification, flushness testing, compliance with AS9100, ISO 9001, NADCAP.

Industry Applications

• Aerospace & Defense: Aircraft skins, control surfaces, interior panels, radar domes (NASM, MS, AS standards)

• Marine & Shipbuilding: Deck plates, hull panels, superstructure assembly

• Medical Equipment: Surgical instruments, imaging devices, diagnostic equipment

• Precision Machinery: Optical equipment, measuring instruments, semiconductor tools

• Transportation: High-speed train bodies, automotive body panels, racing components

• Architectural & Design: Luxury interiors, display systems, furniture manufacturing

Why Choose RAYCHIN?

• Precision Manufacturing: CNC grinding capabilities for exact head angles and flushness

• Aerospace Expertise: Extensive experience with NASM and MS standard countersunk bolts

• Material Specialization: 25+ years working with exotic alloy flush fasteners

• Quality Systems: AS9100 and NADCAP compliant manufacturing processes

• Engineering Support: Flushness optimization and design-for-manufacturability analysis

• Global Supply: Reliable supplier to North America, Europe, Asia-Pacific, Middle East markets

Request Countersunk Bolt Quotation
Contact RAYCHIN for engineering consultation and competitive pricing. Submit your drawings for flat head bolts, countersunk socket screws, or custom flush fasteners.

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