1.Raw Material Inspection & Blanking: Adopt high-quality carbon steel wire rods that comply with international fastener manufacturing standards. Strictly inspect the chemical composition, tensile strength, surface smoothness and internal metallographic structure of raw materials to exclude blanks with cracks, oxide spots and impurity defects. Qualified steel wires are precisely cut into fixed-length blanks according to screw specifications, ensuring consistent material performance and dimensional foundation for subsequent cold forming processing.
2.Surface Pretreatment & Cold Heading
Forming: Complete standardized degreasing, decontamination and lubrication pretreatment to remove surface oil stains and oxide layers, ensuring smooth forming and clean surface texture. Adopt multi-station precision cold heading technology to complete one-piece integral forming of countersunk head, cross recess and screw rod. The integral molding ensures compact metal structure, accurate head taper and standard recess size for stable tool fitting and assembly positioning.
3.Trimming, Shaping & Thread Rolling:
Thoroughly remove residual burrs, flashes and sharp edges generated during cold heading. Conduct precise shaping and flatness calibration to standardize countersunk head radian and flatness, realizing flush mounting effect after installation. Adopt high-precision thread rolling process to form sharp and standard self-tapping threads with uniform pitch and complete tooth profile, ensuring excellent cutting performance, smooth screwing and reliable locking effect.
4.Heat Treatment & Stress Relief:
Implement professional quenching and tempering heat treatment to optimize surface hardness, overall toughness and structural strength. Effectively eliminate residual internal stress produced in cold forming and thread rolling processes. This process significantly improves wear resistance, deformation resistance and fatigue resistance, preventing thread slipping, tooth breaking and screw fracture during long-term repeated tapping and fastening work.
5.Zinc Plating & Full-Range Quality Inspection:
Conduct standardized electro-galvanizing and passivation treatment to form a uniform and compact zinc protective layer on the screw surface, effectively improving anti-rust, anti-oxidation and corrosion resistance. Carry out comprehensive quality inspection covering dimensional tolerance detection, cross recess precision test, thread integrity check, hardness testing, coating thickness detection and assembly performance verification to meet industrial fastening standards.
6.Sorting, Packaging & Warehousing:
Automatically sort and count qualified zinc plated cross recessed countersunk head tapping screws by complete specifications. Adopt dust-proof, moisture-proof and anti-extrusion standardized packaging to protect thread teeth and surface coating from damage and scratches. All finished products are labeled with specification, batch and production information, classified and stored in standardized warehouses, and delivered after strict final inspection.