1.Raw Material Inspection & Blanking: Adopt high-quality carbon steel wire rods that meet international fastener manufacturing standards. Strictly inspect material tensile strength, hardness, surface smoothness and internal metallographic structure to exclude raw materials with cracks, impurities and oxide defects. Qualified steel wires are precisely cut into fixed-length blanks according to screw specifications, ensuring uniform material performance and dimensional consistency for subsequent cold forming.
2.Surface Pretreatment & Cold Heading Forming:
Complete standardized pretreatment including degreasing, cleaning and lubrication to remove surface oil and oxide layers, ensuring smooth cold forming and clean finished surface. Adopt multi-station cold heading technology to complete one-time integral forming of flat countersunk head, cross recess and screw rod. The cold forming process ensures dense metal structure, high head flatness and accurate recess size for stable tool fitting.
3.Trimming, Shaping & Tapping Thread Rolling:
Remove forming burrs, flashes and sharp edges on the screw head and rod surface. Conduct precision shaping and flatness calibration to guarantee neat countersunk head profile for flush installation. Adopt high-precision thread rolling process to form sharp, standard self-tapping threads with uniform pitch and complete tooth profile. The thread structure features strong cutting ability and stable locking performance for smooth self-tapping assembly.
4.Heat Treatment & Stress Stabilization:
Implement professional quenching and tempering heat treatment to improve surface hardness, toughness and overall structural strength. Effectively eliminate residual internal stress generated during cold heading and thread rolling, enhancing wear resistance and fatigue resistance. This treatment ensures the screws are not easy to slip, deform or break during high-speed self-tapping and long-term fastening use.
5.Zinc Plating & Full-Range Quality Inspection:
Conduct standardized electro-galvanizing and passivation treatment to form a uniform and compact zinc coating on the screw surface, greatly improving anti-rust, anti-oxidation and corrosion resistance. Carry out comprehensive quality inspection covering dimensional tolerance detection, cross recess precision test, thread tooth integrity check, hardness testing, coating thickness detection and assembly performance test to meet industrial fastening standards.
6.Sorting, Packaging & Warehousing:
Automatically sort and count qualified zinc plated cross flat head tapping screws by specification. Adopt dust-proof, moisture-proof and extrusion-proof professional packaging to protect threads and surface coating from damage. All finished products are marked with complete product information, classified and stored in standardized warehouses, and delivered after strict final inspection.