M8 M16 Carbon steel Flat head Philip sclotted tapping metal screws Class 4.8 Black finish

• Ordinary self-tapping screws: Feature 'wide thread' design, typically surface plated
• Self-cutting tapping screws: Include various head types (pan head, countersunk head, hexagonal head)
• Self-extruding tapping screws: Typically machine thread with triangular cross-section
• Self-drilling tapping screws: Designed for direct drilling into materials without pre-drilling
• Wallboard tapping screws: Special 60° thread angle with phosphate treatment
• Combination self-tapping screws: Integrated with washers for enhanced fastening

• Lightweight component assembly
• Furniture manufacturing
• Non-structural installations

• Enhanced rust prevention through stable iron tetraoxide film
• Improved surface durability with reduced flaking
• Better sliding properties when combined with rust preventive oils
• Aesthetic appeal with long-lasting surface treatment

Bolt performance level 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and other 10 grades;

4.8 means
Tensile strength Rm=4×100 N/mm2=400 N/mm2=400MPa
Yield strength Re=400×0.8=320MPa

8.8 means:
The first 8 on behalf of the tensile strength Rm
Rm = 8 × 100 N/mm2 = 800 N/mm2 = 800MPa
The second, .8 for the yield strength of the ratio of 0.8
Re800 * 0.8 = 640MPa
8.8 and 4.8 is the strength of the bolt is a different level of general 8.8 level of bolts with 45 steel, 4.8 level with Q235-A