Premium M4 Hex Bolt – High-Strength Metric Fasteners for Industrial Applications

1. Product Overview

Our M4 hex bolt is a precision-engineered metric fastener designed for demanding industrial environments. Manufactured from high-grade carbon steel, stainless steel, or alloy steel, this bolt features a standard 4mm thread diameter and a hexagonal head for secure torque application. Ideal for machinery assembly, automotive components, and structural fastening, the M4 hex bolt delivers reliable clamping force and corrosion resistance. Each bolt undergoes rigorous quality control to ensure dimensional accuracy and tensile strength compliance with ISO 898-1 and DIN 933 standards.

2. Key Features

• Precision Threading: Fully machined M4x0.7 coarse threads ensure smooth engagement and consistent torque values.
• Hexagonal Head Design: Standard 7mm across-flats (AF) hex head allows for easy tightening with wrenches or sockets.
• Material Options: Available in 304/316 stainless steel, grade 8.8/10.9 carbon steel, and A2-70/A4-80 stainless alloys.
• Surface Finishes: Plain, zinc-plated, hot-dip galvanized, or black oxide for enhanced corrosion protection.
• Dimensional Accuracy: Thread pitch tolerance 6g, head height 2.8mm ±0.2mm, shank length tolerance ±0.5mm.
• Strength Grades: Tensile strength up to 1,200 MPa (grade 12.9) for high-stress applications.

3. Technical Specifications

4. Application Scenarios

The M4 hex bolt is a versatile fastener used across multiple industries:

• Electronics Assembly: Securing PCB mounts, heat sinks, and enclosure brackets in consumer and industrial electronics.
• Automotive: Fastening interior trim panels, sensor brackets, and engine components where compact fasteners are required.
• Machinery: Light to medium-duty machine guard attachment, conveyor system components, and jig/fixture assembly.
• Furniture Manufacturing: Connecting metal frames, drawer slides, and adjustable legs in office and industrial furniture.
• Robotics: Precision fastening for servo mounts, actuator linkages, and chassis assembly in collaborative robots.
• HVAC Systems: Securing ductwork brackets, fan housings, and control panel enclosures.

5. Advantages

• Cost-Effective: Competitive pricing without compromising material quality or thread integrity.
• Corrosion Resistance: Stainless steel options withstand harsh environments, including marine and chemical exposure.
• Easy Installation: Standard hex head fits widely available tools; self-locking variants (nylon patch) reduce loosening.
• Consistent Quality: 100% dimensional inspection and batch tensile testing ensure reliable performance.
• Customization: Non-standard lengths, drive types (e.g., hex socket), and coatings available for OEM requirements.
• Global Compliance: Meets CE, RoHS, and REACH standards for export to EU and North American markets.

6. Why Choose Us

As a specialized manufacturer with over 15 years of experience in metric fasteners, we deliver M4 hex bolts that exceed industry expectations:

• In-House Production: Cold forging and CNC threading ensure tight tolerances and consistent quality.
• ISO 9001:2015 Certified: Our quality management system guarantees traceability from raw material to final packaging.
• Fast Lead Times: Standard sizes ship within 3-5 business days; custom orders in 10-14 days.
• Technical Support: Our engineering team assists with material selection, torque specifications, and joint design.
• Volume Discounts: Tiered pricing for bulk orders (5,000+ pcs) with free sample kits for qualification.
• Global Logistics: Reliable shipping via DHL, FedEx, or sea freight with full documentation for customs clearance.

7. FAQ

Q1: What is the difference between DIN 933 and DIN 931 M4 hex bolts?

A: DIN 933 specifies fully threaded bolts (thread extends to the head), while DIN 931 has a partially threaded shank (typically 2-3 times the thread diameter under the head). For most applications, DIN 933 is used when full thread engagement is required.

Q2: Can I use an M4 hex bolt in a corrosive environment?

A: Yes, we recommend A4-80 (316 stainless steel) or hot-dip galvanized carbon steel for marine or chemical environments. For moderate corrosion, zinc-plated or A2-70 (304 stainless) options are suitable.

Q3: What torque should I apply to an M4 hex bolt?

A: Recommended tightening torque varies by grade: 2.5-3.5 Nm for grade 8.8, 4.0-5.5 Nm for grade 10.9, and 5.0-7.0 Nm for grade 12.9. Always consult your joint design and use a calibrated torque wrench.

Q4: Do you offer M4 hex bolts with a nylon patch locking feature?

A: Yes, we provide pre-applied nylon patch (patch lock) on M4 bolts to prevent loosening from vibration. These meet IFI-124 and DIN 267-28 standards.

Q5: What is the minimum order quantity (MOQ) for custom lengths?

A: For custom lengths (e.g., 8mm, 25mm), the MOQ is 1,000 pieces per size. Stock lengths (6, 8, 10, 12, 16, 20, 25, 30, 40, 50, 60mm) have no MOQ.

Q6: How are the bolts packaged for export?

A: Standard packaging is in sealed polyethylene bags (1,000 pcs/bag) with cardboard boxes. For larger orders, we use palletized cartons with stretch wrap. Custom labeling and barcoding are available.

Q7: Can I request a material test certificate?

A: Yes, we provide EN 10204 3.1 material certificates for stainless steel and carbon steel batches at no extra cost. Dimensional inspection reports are available upon request.

Note: All M4 hex bolts are manufactured in compliance with ISO 9001:2015. For technical drawings or custom specifications, contact our sales team with your application details.