2026-01-06

National Standard for Fasteners

The national standard for fasteners is a technical specification system formulated by China for mechanical fasteners such as bolts, screws, and nuts. This standard system covers multiple aspects including dimensional specifications, mechanical properties, tolerance requirements, surface treatments, and testing methods. It is mainly divided into two categories: national standards and industry standards. The national standards are centered around GB/T; for example, GB/T 1237-2000 specifies the marking methods for fasteners, the GB/T 3098 series covers the mechanical performance indicators for bolts and nuts, and the GB/T 5267 series clearly defines the technical requirements for surface treatments such as electroplating and hot-dip galvanizing. Industry standards include specialized regulations in areas such as QC/T 597-1999 pre-coated microcapsule anaerobic dry film adhesive, Q Automotive Standards (for the automotive industry), PEM Standards (for precision electronic components), JB Standards (standards issued by the Ministry of Machinery), HG Chemical Standards, and others. Relevant international standards cover DIN standards from Germany, ASME/IFI/ANSI standards from the United States, JIS standards from Japan, NFE standards from France, BS standards from the United Kingdom, UNI standards from Italy, and ISO international standards. National Standards GB/T 1237-2000 Marking Methods for Fasteners GB/T 152.1-1988 Fasteners—Through-Holes for Rivets GB/T 152.2-1988 Fasteners—Countersunk Holes for Flat Head Screws GB/T 152.3-1988 Fasteners—Countersunk Holes for Round Head Screws GB/T 152.4-1988 Fasteners—Countersunk Holes for Hex Head Bolts and Hex Nuts GB/T 16823.1-1997 Stress Cross-Sectional Area and Bearing Area of Threaded Fasteners GB/T 16823.2-1997 General Rules for Tightening Threaded Fasteners GB/T 16823.3-1997 Testing Methods for Tightening Threaded Fasteners GB/T 16938-2008 Fasteners—Bolts, Screws, Studs and Nuts—General Technical Conditions GB 17464-1998 Connecting Devices—Safety Requirements for Threaded and Non-Threaded Clamping Elements for Connecting Copper Conductors GB/T 17645.511-2010 Industrial Automation Systems and Integration—Part Library—Part 511: Mechanical Systems and General Components—Reference Dictionary of Fasteners GB/T 2670.1-2004 Internal Hexagonal Flower Head Self-Tapping Screw GB/T 3098.1-2000 Mechanical Properties of Fasteners—Bolts, Screws and Studs GB/T 3098.10-1993 Mechanical Properties of Fasteners—Bolts, Screws, Studs and Nuts Made of Non-Ferrous Metals GB/T 3098.11-2002 Mechanical Properties of Fasteners—Self-Drilling Self-Tapping Screws GB/T 3098.12-1996 Mechanical Properties of Fasteners—Conical Nut Proof Load Test GB/T 3098.13-1996 Mechanical Properties of Fasteners—Torque Test and Breaking Torque for Bolts and Screws with Nominal Diameter 1~10mm GB/T 3098.14-2000 Mechanical Properties of Fasteners—Nut Flaring Test GB/T 3098.15-2000 Mechanical Properties of Fasteners—Stainless Steel Nuts GB/T 3098.16-2000 Mechanical Properties of Fasteners—Stainless Steel Set Screws GB/T 3098.17-2000 Mechanical Properties of Fasteners—Preload Test for Hydrogen Embrittlement Inspection—Parallel Support Surface Method GB/T 3098.18-2004 Mechanical Properties of Fasteners—Blind Rivet Testing Methods GB/T 3098.19-2004 Mechanical Properties of Fasteners—Pull-Out Rivets GB/T 3098.2-2000 Mechanical Properties of Fasteners—Nuts—Coarse Thread GB/T 3098.20-2004 Mechanical Properties of Fasteners—Butterfly Nuts—Torque Assurance GB/T 3098.21-2008 Mechanical Properties of Fasteners—Stainless Steel Self-Tapping Screws GB/T 3098.22-2009 Mechanical Properties of Fasteners—Fine-Grain Non-Quenched and Tempered Steel Bolts, Screws and Studs GB/T 3098.3-2000 Mechanical Properties of Fasteners—Set Screws GB/T 3098.4-2000 Mechanical Properties of Fasteners—Nuts—Fine Thread GB/T 3098.5-2000 Mechanical Properties of Fasteners—Self-Tapping Screws GB/T 3098.6-2000 Mechanical Properties of Fasteners—Stainless Steel Bolts, Screws and Studs GB/T 3098.7-2000 Mechanical Properties of Fasteners—Self-Expanding Screws GB/T 3098.8-1992 Mechanical Properties of Fasteners—Threaded Fastener Assemblies for High Temperature Service GB/T 3098.9-2002 Mechanical Properties of Fasteners—Effective Moment Type Steel Hex Lock Nuts GB/T 3103.1-2002 Tolerances for Fasteners—Bolts, Screws, Studs and Nuts GB/T 3103.2-1982 Tolerances for Fasteners—Bolts, Screws and Nuts for Precision Machinery GB/T 3103.3-2000 Tolerances for Fasteners—Flat Washers GB/T 3103.4-1992 Tolerances for Fasteners—Threaded Fastener Assemblies for High Temperature Service GB/T 3104-1982 Fasteners—Hexagon Product Side Width GB/T 5267.1-2002 Fasteners—Electroplated Coatings GB/T 5267.2-2002 Fasteners—Non-Electrolytic Zinc Flake Coatings GB/T 5267.3-2008 Fasteners—Hot-Dip Galvanized Coatings GB/T 5267.4-2009 Fasteners—Surface Treatment—Corrosion-Resistant Stainless Steel Passivation Treatment GB/T 5276-1985 Fasteners—Bolts, Screws, Studs and Nuts—Dimension Codes and Markings GB/T 5277-1985 Fasteners—Through-Holes for Bolts and Screws GB/T 5278-1985 Fasteners—Slotted Pin Holes and Wire Hole GB/T 5779.1-2000 Surface Defects of Fasteners—Bolts, Screws and Studs—General Requirements GB/T 5779.2-2000 Surface Defects of Fasteners—Nuts GB/T 5779.3-2000 Surface Defects of Fasteners—Bolts, Screws and Studs—Special Requirements Industry Standards JB/T 4213-1996 Cold Forging Die for Fasteners—Technical Conditions, Beijing Institute of Mechanical and Electrical Engineering JB/T 7384.13-1994 Fasteners—External Circle Diameter Gauge for Self-Tapping Locking Screws JB/T 7384.14-1994 Fasteners—Small Diameter Caliper for Wood Screw Threads JB/T 7384.2-1994 Fasteners—Height Inspection Molds for Flat Head and Half-Flat Head JB/T 7384.3-1994 Fasteners—Height and Thickness Inspection Molds Between Slot and Supporting Surface JB/T 7384.4-1994 Fasteners—Tightening Height Inspection Molds JB/T 7384.7-1994 Fasteners—Slot Width Plug Gauge JB/T 7384.8-1994 Fasteners—Slot Depth Plug Gauge JB/T 4213-1996 Cold Forging Die for Fasteners—Technical Conditions, Beijing Institute of Mechanical and Electrical Engineering JB/T 7384.13-1994 Fasteners—External Circle Diameter Gauge for Self-Tapping Locking Screws JB/T 7384.14-1994 Fasteners—Small Diameter Caliper for Wood Screw Threads JB/T 7384.2-1994 Fasteners—Height Inspection Molds for Flat Head and Half-Flat Head JB/T 7384.3-1994 Fasteners—Height and Thickness Inspection Molds Between Slot and Supporting Surface JB/T 7384.4-1994 Fasteners—Tightening Height Inspection Molds JB/T 7384.7-1994 Fasteners—Slot Width Plug Gauge JB/T 7384.8-1994 Fasteners—Slot Depth Plug Gauge JB/T 9151.1-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Bolts, Screws, Studs and Nuts JB/T 9151.2-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Wood Screws JB/T 9151.3-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Self-Tapping Screws JB/T 9151.4-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Washers JB/T 9151.5-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Pins JB/T 9151.6-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Rivets JB/T 9151.7-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Retaining Rings JB/T 9151.1-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Bolts, Screws, Studs and Nuts JB/T 9151.2-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Wood Screws JB/T 9151.3-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Self-Tapping Screws JB/T 9151.4-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Washers JB/T 9151.5-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Pins JB/T 9151.6-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Rivets JB/T 9151.7-1999 Testing Methods for Fasteners—Dimensions and Geometric Accuracy—Retaining Rings QC/T 597-1999 Pre-Coated Microcapsule Anaerobic Dry Film Adhesive for Threaded Fasteners SJ 2494-1984 Fasteners—Cross-Slot Flat Head Screws SJ 2495-1984 Fasteners—Self-Tapping Threads SJ 2496-1984 Fasteners—Heat-Treated Steel Self-Tapping Screws—Mechanical Properties SJ 2497-1984 Fasteners—Cross-Slot Pan Head Self-Tapping Screws SJ 2498-1984 Fasteners—Cross-Slot Countersunk Self-Tapping Screws SJ 2499-1984 Fasteners—Cross-Slot Half-Countersunk Self-Tapping Screws SJ 2500-1984 Fasteners—Cross-Slot Flat Head Self-Tapping Screws SJ 2501-1984 Fasteners—Cross-Slot Pan Head Flange Self-Tapping Screws SJ 2502-1984 Fasteners—Cross-Slot Pan Head Ordinary Thread Self-Tapping Screws SJ 2503-1984 Fasteners—Cross-Slot Countersunk Ordinary Thread Self-Tapping Screws SJ 2504-1984 Fasteners—Cross-Slot Flat Head Ordinary Thread Self-Tapping Screws SJ 2505-1984 Fasteners—Cylindrical Head Non-Loosening Screws SJ 2506-1984 Fasteners—Sliding Nuts SJ 2507-1984 Fasteners—Riveted Round Nuts SJ 2508-1984 Fasteners—Smooth Hexagonal Extra-flat Fine-Tooth Nuts SJ 2509-1984 Fasteners—Riveted Square Nuts SJ 2510-1984 Fasteners—Handle Washers SJ 2511-1984 Fasteners—Insulating Washers SJ 2512-1984 Fasteners—Insulating Small Washers SJ 2823-1987 Fasteners for Television Receivers—Cross-Slot Flat Round Head Self-Tapping Screws SJ 2824-1987 Fasteners for Television Receivers—Cross-Slot Large Spherical Head Self-Tapping Screws SJ 2825-1987 Fasteners for Television Receivers—Cross-Slot Large Spherical Flange Self-Tapping Screws SJ 2826-1987 Fasteners for Television Receivers—Cross-Slot Hexagonal Head Self-Tapping Screws SJ 2827-1987 Fasteners for Television Receivers—CRT Bracket Bolts SJ 2828-1987 Fasteners for Television Receivers—Cross-Slot Pan Head Screws SJ 2829-1987 Fasteners for Television Receivers—Cross-Slot Large Spherical Head Screws SJ 2830-1987 Fasteners for Television Receivers—Cross-Slot Large Spherical Flange Screws SJ 2831-1987 Fasteners for Television Receivers—Cross-Slot Large Spherical Head Self-Tapping Locking Screws SJ 2832-1987 Fasteners for Television Receivers—Cross-Slot Large Spherical Flange Self-Tapping Locking Screws SJ 2833-1987 Fasteners for Television Receivers—Cross-Slot Self-Tapping Locking Screw Technical Conditions SJ 2834-1987 Fasteners for Television Receivers—Cross-Slot Pan Head Combined Screws with Flat Washers SJ 2835-1987 Fasteners for Television Receivers—Cross-Slot Pan Head Combined Screws with Spring Washers SJ 2836-1987 Fasteners for Television Receivers—Cross-Slot Pan Head Combined Screws with Spring Washers and Flat Washers SJ 2837-1987 Fasteners for Television Receivers—Cross-Slot Combined Screw Technical Conditions SJ 2838-1987 Fasteners for Television Receivers—Cross-Slot Large Spherical Head Combined Self-Tapping Screws with Flat Washers SJ 2839-1987 Fasteners for Television Receivers—Cross-Slot Large Spherical Head Combined Self-Tapping Screws with External Tooth Washers SJ 2840-1987 Fasteners for Television Receivers—Cross-Slot Hexagonal Head Combined Self-Tapping Screws with Flat Washers SJ 2842-1987 Fasteners for Television Receivers—Hexagonal Flange Face Nuts SN 0030-1992 Inspection Procedures for Export Fasteners TB 2129-1990 High-Strength Fasteners for Rail Insulated Joints Fasteners are also called screws; the terminology differs, but the underlying meaning remains the same. Each type of fastener is a general term for a class of mechanical parts used to securely join two or more parts (or components) into a single unit. Fastener products all involve standards covering several aspects. 1. Standards related to fastener product dimensions: These specifically define the basic dimensions of the products; for threaded products, they also include the basic dimensions of the threads, thread termination, shoulder distance, chip-relief grooves and chamfers, as well as the end dimensions of external-threaded parts. 2. Standards related to fastener product technical conditions: These mainly include standards on product tolerances, mechanical properties, surface defects, surface treatments, product testing, and corresponding specific requirements. 3. Standards related to screw product acceptance inspection, marking, and packaging: These specifically define the acceptable quality levels and sampling plans for random inspections during product release, as well as the methods for product marking and packaging requirements. 4. Standards for marking methods of Standard Parts, Fasteners, Screws, and Bolts: These specifically define both complete marking methods and simplified marking methods for products. 5. Other standards related to fasteners: such as standards for fastener terminology and standards for fastener product weights.

2026-01-06

National Standard for Part Code Numbering Rules

The rules for part designation codes are not covered by a single national standard; rather, they involve multiple national and industry standards, depending on the type of part, its application area, and industry-specific regulations. Below is an overview of some common national and industry standards related to part designation codes: I. Designation Code Rules in National Standards Mandatory National Standards (GB) Code: GB Meaning: These standards have legal status and must be strictly enforced. They cover areas such as human health, personal safety, and property security. Although they do not directly address part designation codes, they provide fundamental safety and quality requirements for the design, production, and use of parts. Recommended National Standards (GB/T) Code: GB/T Meaning: These standards are not mandatory but represent advanced technologies and best practices within the industry. In terms of part designation codes, they may cover part classification, naming conventions, and other related guidelines to enhance the universality and interchangeability of parts. National Standards for Specific Fields For example, National Metrological Technical Specifications (JJF) and National Metrological Verification Procedures (JJG): While these standards primarily focus on the field of metrology, the designation codes for certain metrological components may also follow these specifications. II. Designation Code Rules in Industry Standards Industry standards are developed when there are no national standards or when unified technical requirements are needed within a specific industry. Different industries have their own unique rules for part designation codes, such as: Mechanical Industry (JB) Code: JB Meaning: Mechanical industry standards may include rules for part classification, naming, and designation coding to ensure the universality and interchangeability of mechanical parts. Automotive Industry (QC) Code: QC Meaning: Automotive industry standards provide detailed regulations for the designation codes of automotive parts, including part classification, naming, and coding rules, to meet the complexity and efficiency requirements of automobile manufacturing. Other Industries For example, the textile industry (FZ), pharmaceutical industry (YY), and electronics industry (SJ): These industries also have their own unique rules for part designation codes to meet the specific needs of their respective fields.

2026-01-06

A Comprehensive Analysis of Part Technical Requirements in Manufacturing

01 Overview of Technical Requirements In manufacturing, the technical requirements for parts are crucial to ensuring product quality and performance. These requirements cover multiple stages—from surface treatment to heat treatment—and each stage directly affects the final quality of the part. Next, we’ll delve deeper into these technical requirements and reveal the secrets behind part manufacturing. ▣ General Technical Specifications In manufacturing, the technical requirements for parts are crucial to ensuring product quality and performance. These requirements cover multiple stages—from surface treatment to heat treatment—and each stage directly affects the final quality of the part. ▣ Surface Treatment Requirements for Machined Parts In the process of part manufacturing, surface treatment is a critical step. It involves removing oxide scale from the machined parts, ensuring that the part’s surface is free from scratches, abrasions, and other defects. Additionally, burrs and flash must be removed, and sharp edges rounded off. Furthermore, there are clear standard requirements for unspecified chamfers and undercuts: chamfers should be 0.5×45°, and undercuts should be 1.2×0.3. Ultimately, the surface of the machined part must be smooth and burr-free to meet product quality and performance requirements. ▣ Technical Requirements for Unspecified Tolerances In the manufacturing of metal parts, the technical requirements for unspecified tolerances cover various aspects such as dimensions, shape, position, and roughness, aiming to ensure the manufacturing accuracy and quality of the parts. By strictly adhering to these technical requirements, the performance of the parts can be further optimized to meet the overall design needs of the product. ▣ Limit Deviations for Unspecified Dimensional Tolerances In the manufacturing of metal parts, the limit deviations for unspecified dimensional tolerances must comply with GB/T 1804-m; while unspecified geometric tolerances should be standardized according to GB/T 1184-K. Additionally, for unspecified length dimensions, the allowable deviation is ±0.5. Compliance with these standards is essential to ensure the manufacturing accuracy and quality of metal parts. 02 Surface and Heat Treatment Technologies ▣ Surface Treatment Technical Requirements In the manufacturing of metal parts, surface treatment technology is an indispensable step. Surface treatment not only affects the appearance quality of the part but also has a profound impact on its service life and performance. Therefore, it is crucial to strictly follow relevant technical standards to ensure that every step of the surface treatment achieves the desired effect. ▣ Detailed Explanation of Surface Treatment Technologies There are many types of surface treatment technologies for metal parts, each with its specific applications and effects. For example, white (black) zinc plating provides corrosion protection for the part; while paint (plastic coating) application gives the part a colorful and attractive appearance. In addition, there are treatments such as blackening, electrophoretic coating, and chrome plating, each with unique functions, collectively forming a rich system of surface treatments for metal parts. Meanwhile, to meet specific process requirements—such as increasing friction or providing an aesthetically pleasing texture—surface knurling and straight (grid) textures are also employed, with standards following GB/T 6403.3. The comprehensive application of these technologies greatly enhances the performance and service life of metal parts. ▣ Key Points of Heat Treatment Technology Heat treatment technology is a critical step in the manufacturing process of metal parts. Through steps such as heating, holding, and cooling, it alters the internal microstructure of the metal material, thereby improving its mechanical properties and service life. Different heat treatment processes produce different effects: quenching significantly increases the hardness and wear resistance of the metal, while tempering maintains its toughness. When performing heat treatment, it is essential to strictly adhere to relevant standards and technical requirements to ensure that the metal parts achieve the expected performance indicators. 03 Technical Requirements for Specific Parts ▣ Casting Part Technical Requirements In the manufacturing of metal parts, casting technology is equally indispensable. It involves multiple stages, including casting design, manufacturing, and post-processing, aimed at ensuring that the castings have the required physical properties and dimensional accuracy. The quality of the castings directly affects the overall performance and service life of the product; therefore, strict adherence to casting technical requirements is particularly important. ▣ Detailed Explanation of Die-Casting Part Technical Requirements In the manufacturing of metal parts, die-casting technology plays a vital role. It covers a series of technical specifications, including dimensional limit deviations, geometric tolerances, chamfers, wall thickness, rib thickness, transition fillets, draft angles, etc., aimed at ensuring that the castings have excellent physical properties and dimensional accuracy. Moreover, the quality of the castings is closely monitored: they must be full and smooth, free from any defects such as porosity, shrinkage cavities, cracks, slag inclusion, or insufficient material. At the same time, the indentations left by ejector pins and core-pulling rods must also be kept below a certain depth to ensure the integrity of the casting surface. The entire manufacturing process must strictly follow the GB/T 15114 “Aluminum Alloy Die Castings” standard and undergo necessary machining and oil-based protection after surface treatment. ▣ Sand Casting Technical Requirements In the sand casting process, a series of strict technical specifications must be followed. First, for unspecified casting fillets, they should be controlled within the range of R5-10. Second, after completion, the castings must undergo thorough sand removal to ensure that the risers and gates are completely cleaned and smoothed. In addition, the castings need to undergo artificial aging treatment to enhance their physical properties. In terms of quality, the castings must never have defects such as sand holes, porosity, shrinkage cavities, or cracks. ▣ Stamping Part Technical Specifications In the production of stamped parts, strict inspections must be carried out before stamping to ensure that the dimensions and surface quality meet the standards. Secondly, during the stamping process, process parameters such as stamping force and stamping speed must be strictly controlled to ensure the forming quality and precision of the stamped parts. Additionally, after stamping, the castings require careful surface treatment to improve their appearance quality. ▣ Technical Requirements for Plastic Parts In the production and inspection of plastic parts, a series of strict technical standards must be followed. These standards not only affect the dimensional accuracy of the products but also play a crucial role in their performance and durability. In terms of dimensions, plastic parts must strictly comply with GB/T 15055-m. If no special markings are provided, this standard should be applied by default to ensure dimensional accuracy. ▣ Technical Requirements for Welded Parts The technical requirements for welded parts include several aspects. First, for unspecified tolerance linear and angular dimensions, their limit deviations should follow the GB/T 19804-B level standard. Second, weld quality is crucial—it should have a uniform and smooth appearance, and welding slag must be thoroughly removed. ▣ Technical Requirements for Various Parts and Components During the welding process, various parts and components also have their own specific technical standards. These standards cover multiple aspects, including dimensions, shape, position, and material, aimed at ensuring that each welded part meets the predetermined quality requirements.

2026-01-12

General Component Selection: Practical Considerations from Operational Condition Matching to Cost Optimization

The selection of standard components is a critical step in the design and manufacturing of mechanical products, directly affecting the product’s performance reliability, service life, and overall cost. Although selecting seemingly simple parts such as bolts and bearings may appear straightforward, failure to fully match them with the actual operating conditions can lead to frequent product failures and a sharp increase in maintenance and operational costs. By contrast, a scientifically sound and rational component selection process can optimize costs and enhance efficiency while ensuring that product performance remains robust. Therefore, mastering the logic and methods for selecting standard components is of paramount importance for professionals in the manufacturing industry.

2026-01-12

Standardization of General-Purpose Parts: The Cornerstone of Efficient Collaboration in Manufacturing

In the industrial chain system of modern manufacturing, standard components—serving as the fundamental building blocks of various types of equipment—have a standardized development level that directly affects industry collaboration efficiency, product quality stability, and cost-control capabilities. From fasteners such as bolts and nuts to transmission components like bearings and gears, the standardization process of these universal parts has consistently accompanied the upgrading and iterative advancement of manufacturing, becoming a crucial support for driving high-quality development in the industry.

2026-01-12

Classification of combinations of standard parts

In the mechanical manufacturing system, standard parts serve as the “building blocks” for various types of equipment. Cars, home appliances, machine tools, and many other products all rely on components such as bolts, gears, and bearings for support. The classification and organization of standard parts are not merely a simple accumulation of components; rather, they represent a scientifically structured integration based on dimensions such as function, application scenarios, and standards. This systematic approach provides clear guidance for production and warehousing, enhances R&D efficiency, reduces supply-chain costs, and plays a crucial role in the standardized development of manufacturing.