1. Product Overview
 
This product is a standard M8 metric hex socket head cap screw, also known as a socket head cap screw or Allen bolt. Its head features a classic countersunk hex socket design, requiring a corresponding-sized hex key for tightening. The product is manufactured through precision cold forging and tempered heat treatment, offering high strength, compact structure, strong fastening force, and a clean appearance. It is an essential fastener widely used in machinery, electronics, furniture, home decoration, and many other fields.
 
2. Detailed Specifications
 
Parameter Item----------Specification Value (Metric)  
Standard Code --- DIN 912 / ISO 4762 / GB 70.1 (Other standards can be provided upon request)
Thread Size --- M8
Pitch --- Standard Pitch: 1.25mm
Fine Pitch Optional --- 1.0mm (must be specified)
Nominal Diameter --- 8 mm
Head Diameter --- Approx. 13 mm
Head Height --- Approx. 8 mm
Hex Socket Size --- 6 mm (Use a 6mm hex key)
Common Length (L) --- 16mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 60mm, 70mm, 80mm... (Other lengths can be customized)
Property Class --- Class 8.8 (Most common), Class 10.9, Class 12.9 (High-strength options available)
Surface Treatment --- Zinc-Plated Bright (Standard rust prevention), Zinc-Plated Blue-White, Black Oxide, Dacromet (High corrosion resistance), Stainless Steel Natural (304/316)
Material --- Low Carbon Steel (Class 8.8), Medium Carbon Steel (Class 10.9/12.9), Stainless Steel 304/316
Dimension Diagram:
(A diagram labeling head diameter, length, and thread length should be inserted here)
 
3. Key Features & Advantages
 
Powerful Clamping Force: The hex socket allows for higher torque application without slipping, ensuring a secure and reliable connection.
Space-Saving: The cylindrical head design requires no external wrench clearance, making it ideal for use in confined or limited spaces.
Neat and Aesthetic: The head can be countersunk into the workpiece, maintaining a flat and smooth surface with no protrusions for a clean appearance.
High Strength and Durability: Made from high-quality steel and heat-treated (Class 8.8 and above), it offers excellent tensile strength and toughness for high-load applications.
Multiple Options: Available in various strength classes, surface treatments, and lengths to meet different environmental and mechanical requirements.
 
4. Applications
 
This M8 hex socket head cap screw is extremely versatile and is a "universal key" in industrial manufacturing and maintenance.
Machinery Equipment: Assembly and fastening of machine tools, molds, transmission equipment, and production lines.
Automotive Industry: Fastening engine components, chassis, brake systems, and internal structures.
Electronics: Internal connections in server chassis, heat sinks, hard drive racks, and precision instruments.
Furniture & Home Decoration: Installation of high-end DIY furniture, kitchen and bathroom hardware, stairs, doors, and windows.
Rail Transportation & New Energy: Connections for equipment panels, brackets, and battery enclosures.
Outdoor Facilities: Installation of fitness equipment, outdoor railings, and lighting fixtures.
 
5. Installation Guide
 
Tool Selection: Always use a accurately sized, high-quality 6mm hex key or bit. Worn tools can easily damage the hex socket.
Align Vertically: Fully insert the key into the socket and apply force perpendicular to the bolt head to avoid stripping the socket.
Torque Recommendation: For critical connections, use a torque wrench and refer to the following recommended torque (Class 8.8 bolt):
M8x1.25 (Class 8.8) Recommended Torque: Approx. 25 - 30 N·m
(Note: Actual torque should be adjusted based on working conditions, lubrication, and nut material.)
 
6. Frequently Asked Questions (FAQ)
 
Q1: What does "M8" mean in the bolt specification?
A: "M" stands for metric thread, and "8" indicates the nominal thread diameter of 8 millimeters.
 
Q2: What does property class 8.8 mean?
A: Class 8.8 indicates a tensile strength of 800 MPa and a yield strength ratio of 0.8, meaning the yield strength is 640 MPa. This is the most commonly used medium-strength grade.
 
Q3: How do I choose the right bolt length?
A: The bolt length should ensure that 2-3 threads protrude beyond the nut after tightening. The general formula is: Bolt Length ≥ Total Thickness of Connected Parts + Washer Thickness + Nut Thickness + (2~3)P (where P is the pitch).
 
Q4: What is the difference between stainless steel and zinc-plated steel?
A: Stainless Steel (304/316) offers excellent corrosion and rust resistance, making it suitable for humid, outdoor, or chemically corrosive environments, though it is slightly more expensive and has lower strength than alloy steel of the same grade. Zinc-Plated Steel is cost-effective with general rust prevention, suitable for most indoor applications.
 
Q5: What should I do if the hex socket is stripped?
A: Try using a slightly larger star-shaped wrench (Torx key) tapped into the socket or use a stripped screw extractor. Prevention is better than cure—always use the correct tools and proper techniques.
 
7. Packaging & Delivery
 
Standard Packaging: 100 pieces/bag, 1000 pieces/box, or customized packaging upon request.
Stock Availability: Conventional specifications are readily available for quick shipping.
Customization Services: Non-standard lengths, special surface treatments, and special materials can be customized.