Fastener and material processing and treatment process flow

Fasteners are two or two or more parts (or components) fastening connection to become a see the whole of a class of mechanical parts used in the general term. Fasteners are characterized by a wide variety of specifications, performance and use of different, and standardization, serialization, generalization degree is very high, so some people have national standards of a class of fasteners known as standard fasteners, or referred to as standard parts. And some others are called non-standard parts. But their important role is the same. Today we will introduce the fasteners and materials processing and handling process.

  1.High-strength threaded fastener product flow

  High-strength threaded fasteners production process for the modification of raw materials → cold heading forming → thread processing (rolling or thread rolling) → heat treatment → surface treatment → sorting and packaging, 10.9 level above the general use of heat treatment after rolling process.

  2.Automobile fastener materials

  High-strength bolts commonly used steel grade 8.8 bolts with 35 steel, 45 steel, ML35 steel; 10.9 bolts with 35CrMo; 40Cr; 12.9 bolts with 35CrMo, 42CrMo, SCM435.

  Domestic fasteners with raw materials is basically hot-rolled state, and like Japan and other countries produce fasteners with steel is basically direct cold heading state, the user does not need to pre-treatment, can reduce costs from the link.

  The common failure form of fastener failure is assembly elongation, fatigue fracture and delayed fracture.

  3. Cold heading forming and thread processing (rolling or thread rolling, tapping)

  Threaded fastener quality in addition to material, forming equipment and thread processing equipment and molds (production process and its equipment) is to ensure the quality of the key factors. Especially in the state of large quantities of multiple varieties of supply, the high processing accuracy requirements of automotive fasteners, how to ensure product consistency and defect prevention is one of the problems facing the production of fasteners.

  4.Heat treatment

  Heat treatment and tempering is to improve the overall mechanical properties of fasteners to meet the product requirements of the tensile strength value and flexural strength ratio. Tempering heat treatment process of raw materials, furnace temperature control, furnace atmosphere control, quenching medium have strict requirements. The main control defects are carbon segregation in the heart of the material, material and surface decarburization in the annealing process, cold heading cracks, quenching cracks and deformation in the tempering.

  Heat treatment process: loading → cleaning → heating → quenching → cleaning → tempering → coloring → offline.

 5.Surface treatment

  The surface treatment of automobile fasteners mainly has the following ways. a. Non-electrolytic plating for hot dip plating, penetration plating, mechanical plating, Dacromet sintered film, etc. b. Electrolytic plating for zinc plating, zinc-nickel alloy, zinc-iron alloy, etc. c. Phosphatization treatment. d. Blackening treatment, etc.