China Hexagon Socket Bolt Manufacturers Suppliers Factory - Hexagon Socket Bolt in Stock

Product Overview

Kappa Fasteners produces industrial-grade Hexagon Socket Bolts (commonly referred to as socket head cap screws) engineered for high-preload and space-restricted fastening applications. Utilizing cold-heading and precision hot-forging followed by controlled atmosphere heat treatment, our bolts ensure high tensile strength, precise socket depth, and consistent torque-tension relationships.

Black Hexagon Socket Head Cap Bolt Fine Thread Grade 10.9
The difference comes down to pitch: for the same diameter, fine threads have a smaller pitch, so more turns fit in a given length. That makes them the better choice when the joint needs precise adjustment or a shorter thread engagement.
view more
Allen Bolt DIN912 Stainless Steel 304 A2-70
304 handles moisture, humid air and ordinary indoor/outdoor exposure well — which is why it's the default choice for fasteners in everyday environments.
view more
Carbon Steel Hexagon Socket Countersunk Head Cap Bolt Gra...
Tightened with a hex key or bit; no wrench clearance needed around the head, so it fits tight assemblies.
view more
Stainless Steel DIN7991 CSK Head Hex Socket Bolt
DIN 7991 countersunk screws are used where the head must sit flush: machine guards and covers, sheet-metal and panel assemblies, jig and fixture plates, and furniture fittings. Because the 90° head sinks into a countersink, it won't...
view more

Technical Specifications

Parameter	Metric Specification	Imperial Specification
Standard Equivalents	ISO 4762, DIN 912, GB 70.1	ASME B18.3, ASTM A574
Diameter Range (Thread Size)	M3 to M30	#4 to 1-1/2 inch
Length Range	6 mm to 300 mm	1/4 inch to 12 inch
Property Classes / Grades	Class 10.9, Class 12.9	ASTM A574, Alloy Steel Grade 8 / 9
Raw Material Base	SCM435 (AISI 4135), 40Cr, 35CrMo	Alloy Steel (AISI 4140 / 8740)
Tensile Strength	Min. 1040 MPa (Class 10.9) / Min. 1220 MPa (Class 12.9)	Min. 140,000 psi (ASTM A574)
Thread Type	Metric Coarse / Fine (ISO 68-1)	UNC / UNF (ANSI B1.1)
Drive Type	Internal Hexagon (Hex Socket)	Internal Hexagon (Allen Drive)

Key Features

Controlled Socket Depth & Tolerance:

Internal hex broaching adheres strictly to GO/NOGO gauge checks, preventing driver cam-out and wrench slippage during high-torque pneumatic or electric tool installation.

Cold-Formed & Rolled Threads:

Thread rolling is performed after heat treatment on Class 10.9 and 12.9 fasteners, resulting in superior fatigue resistance and continuous grain flow along the thread root.

Hydrogen Embrittlement Relief:

Electroplated high-tensile bolts (Class 12.9) undergo immediate baking within 4 hours post-plating at 190°C–220°C to eliminate absorbed atomic hydrogen.

Underhead Fillet Radius:

Optimized fillet radius design distributes stress concentration evenly beneath the head-shank junction, increasing cyclic fatigue life in dynamic machinery.

Surface Finishes & Corrosion Resistance

Selecting the correct coating is critical to prevent galvanic corrosion and premature failure. Kappa Fasteners offers certified industrial surface treatments:

Finish Type	Salt Spray Test (SST) Resistance	Typical Application Environment
Zinc Flake Coating (Geomet / Dacromet)	720 to 1000+ Hours (Red Rust)	Outdoor wind energy, agricultural machinery, marine environments
Zinc Plating (Clear / Yellow / Black Passivated)	72 to 240 Hours	Indoor industrial automation, general machinery, electronics
Black Oxide (Thermal Blackening)	48 to 72 Hours (Light oil film required)	Precision internal machine tools, injection molds (low corrosion risk)
Cadmium Plating	500+ Hours	Aerospace ground support equipment, defense applications
Hot-Dip Galvanizing (HDG)	500+ Hours	Heavy structural steel, outdoor utility poles

Socket Head Flange Screws 8.8 Grade Blue‑White Zinc Plated Manufacturer

Applications

CNC Machine Tools & Spindles: Securing linear guide rails, ball screw supports, and heavy clamping modules where positional accuracy and high preload are mandatory.

Injection Molding & Die Casting Dies: Operating under high temperatures and cyclic clamping forces; uses Class 12.9 alloy steel bolts to resist thermal fatigue.

Industrial Robotics & Automation Jigs: Fastening high-acceleration robotic arms and multi-axis gantry frames requiring high shear strength and compact head clearances.

Wind Turbine Gearboxes & Nacelles: Withstanding heavy vibrational resonance and wind load stresses in remote, corrosive outdoor environments.

OEM Solutions & Custom Manufacturing

Standard off-the-shelf fasteners do not fit every engineering challenge. Kappa Fasteners provides full-cycle OEM/ODM manufacturing based on customer technical drawings and specifications:

01/

Non-Standard Dimensions: Customized shank lengths, partial/full thread configurations, and oversized or reduced head diameters.

02/

Special Materials: Manufacturing using stainless steel grades (A2-70, A4-80, 316L, 17-4PH) or high-temperature superalloys (Inconel 718, Monel, Titanium Gr.5) for extreme chemical or thermal conditions.

03/

Custom Head Markings: Embossing company logos, traceability heat codes, or property class stamps directly onto the fastener head.

04/

Specialized Packaging: Kitting, barcoded polybagging, and custom labeling tailored for automated assembly lines or retail distribution.

Quality Control & Testing Protocols

We maintain strict control over metallurgy, mechanical properties, and dimensional conformity across all production lines:

Raw Material Verification: Spectrometer chemical composition analysis performed on every incoming coil of steel wire to verify alloy percentages (Carbon, Chromium, Molybdenum).

In-Process Dimensional Inspection: Optical sorting machines and multi-axis projectors check thread pitch diameter, head height, concentricity, and socket width on 100% of critical batches.

Mechanical Laboratory Testing:
Universal Tensile Testing Machine (measuring tensile strength, yield strength, and elongation).
Vickers / Rockwell Hardness Testing (HRC 39–44 for Class 12.9).
Wedge Load Testing to verify head-to-shank integrity.
Magnetic Particle Inspection (MPI) for surface and sub-surface defect detection.

Traceability: Every shipment includes an EN 10204 3.1 Material Test Report (MTR) mapping heat numbers directly to final packaging labels.

316 Stainless Steel Socket Head Cap Screws DIN 912 A4-70 Hex Allen Bolts manufacturers

Packaging & Shipping

Export-Standard Packaging: Fasteners are packed in heavy-duty corrugated cartons lined with moisture-resistant VCI (Volatile Corrosion Inhibitor) plastic bags. Pallets are heat-treated and ISPM 15 compliant.
Bulk & Retail Options:
• Bulk industrial cartons (20kg – 25kg per box) for automated feeding systems.
• Small-box packaging and blister packs for MRO distributors.
• Global Logistics: Flexible FOB, CIF, or DDP shipping terms via sea freight (Ningbo/Shanghai port) or air express for urgent prototype requirements.

Frequently Asked Questions

Q: What is the difference between Class 10.9 and Class 12.9 hexagon socket bolts?

A: Class 10.9 has a nominal tensile strength of 1000 MPa and a minimum yield strength of 900 MPa. Class 12.9 offers higher mechanical capacity with a nominal tensile strength of 1200 MPa and minimum yield of 1080 MPa. Class 12.9 is typically specified for high-preload joints subject to severe dynamic stress, but requires careful torque control and hydrogen embrittlement avoidance.

Q: Can you provide EN 10204 3.1 Test Reports with our shipment?

A: Yes. Every batch produced by Kappa Fasteners is fully traceable from raw material wire rod to finished goods. We issue 3.1 MTR documents covering chemical analysis, mechanical property test results, and surface coating thickness reports upon request.

Q: Do high-tensile socket bolts require hydrogen embrittlement relief?

A: Yes. All electroplated fasteners with hardness above 320 HV (such as Class 10.9 and 12.9) undergo a mandatory baking process within 4 hours of electroplating. This process operates at 190°C–220°C for a minimum of 4–8 hours to dispel atomic hydrogen and prevent delayed catastrophic brittle fracture.

Q: What is the minimum order quantity (MOQ) for non-standard or custom-coated fasteners?

A: For non-standard dimensions or specific coatings (such as Geomet or specialized PTFE), the MOQ typically depends on wire diameter and batch setup requirements, generally starting around 5,000 to 10,000 pieces per size. Contact our engineering sales team for exact project evaluations.

Request a Quote

Need reliable, high-tensile Hexagon Socket Bolts for your manufacturing line or distribution network? Submit your specifications below to receive a formal quotation with pricing, lead times, and technical datasheets within 24 hours.
Required Information to Include: Standard (ISO/DIN/ANSI), Thread Size & Length, Quantity, Material/Grade, Surface Finish, and Target Delivery Port.

Hebei Kappa Metal Products Co., Ltd. is one of the most experienced hexagon socket bolt manufacturers and suppliers in China. With a professional production team, we are able to meet the needs of the majority of our customers. Please rest assured to buy bulk high quality hexagon socket bolt in stock here from our factory.

Allen Bolt DIN912 Stainless Steel 304 A2 70, allen key screw cap screw hex socket head, countersunk hex head bolt