Hex Head Phillips Bolts

1.What is a Hex Head Phillips Bolt？

Hex Head Phillips Bolts are a specialized type of fastener that combines two drive systems: a hexagonal external head and an internal Phillips recess (Type I or Type II, conforming to ASTM F116-13).

• Hex head: Allows high torque application with a wrench (ANSI B18.2.1 / DIN 933).

• Phillips recess: Enables Screwdriver operation, typically PH1, PH2, or PH3.

• Dual-drive design: Provides flexibility for both high-torque installation and fine adjustments.

2. Sizes & Standards

• Common Sizes

• Metric: M3 – M20

• Imperial: #4 – ¾"

• Phillips Torque Limits

• Example: PH2 drive handles up to ~25 N·m before cam-out.

• Hex Head Torque

• Example: M12 Bolts withstand up to ~200 N·m.

• Optional Features

• Serrated flange under head (DIN 6921), providing 0.5–2.5 N·m locking torque.

3. Materials & Strength

• Carbon Steel

• Grade 5: 120 ksi (827 MPa)

• Grade 8: 150 ksi (1034 MPa)

• Stainless Steel

• 304 / 316: 70–80 ksi (485–550 MPa)

• Aluminum Alloy

• 6061-T6: 45 ksi (310 MPa)

• Protective Coatings

• Zinc plating: 5–15 µm (ASTM B633)

• Hot-dip galvanizing: 45–80 µm (ASTM A153)

• Black oxide: 0.5–1.5 µm (MIL-DTL-13924D)

4. Applications

• Automotive

• Brake calipers, transmission housings, engine brackets

• Example: M10 Bolts in suspension, torque 40–60 N·m

• Aerospace

• Non-critical interior panels, avionics racks

• Stainless steel or titanium, torque 10–30 N·m

• Electronics

• Server and networking chassis assembly

• M4–M8 bolts, torque 5–15 N·m

• Industrial Machinery

• Mounting motors, pumps, guards

• Corrosion-resistant coatings for harsh environments

• Consumer Products

• Furniture, outdoor equipment

• Often with pre-applied thread-locking compounds (nylon patch, 0.5–1.5 N·m breakaway torque)

5. Installation & Maintenance

• Material Selection

• Stainless steel for corrosive environments

• Galvanized steel for outdoor exposure

• Lubrication

• Apply anti-seize (copper-based, up to 1100°C) to reduce galling

• Torque Control

• Follow ISO 16047

• Example: M10 Grade 8.8 → 50–60 N·m

• Use hex head for high torque to avoid Phillips cam-out

• Vibration Resistance

• Apply medium-strength threadlocker (e.g., Loctite 243, vibration resistance up to 500 Hz)

• Re-torque after 100–200 hours in vibrating conditions

• Inspection & Cleaning

• Replace if coating loss >10% or head/thread deformation is found

• Clean with non-abrasive methods (wire brush + isopropyl alcohol)

• Storage

• Dry, low-humidity conditions with desiccants

• Organize by size and material to avoid galvanic corrosion