GB/T 6188-2017 Hexalobular Internal Drive for Bolts
Giới thiệu
The hexalobular internal driving feature, commonly known as Torx or hexalobe, enhances torque transmission and reduces cam-out in fasteners. This design is critical in high-performance applications across automotive, aerospace, and electronics industries.
GB/T 6188-2017 specifies the dimensions and requirements for hexalobular sockets used in bolts and screws, aligning with international standards like ISO 10664. It ensures compatibility, reliability, and interchangeability of fasteners.
This standard applies to metallic fasteners with internal hexalobular drives, promoting secure assembly and disassembly. It defines socket sizes from T1 to T100, covering a wide range of nominal thread diameters.
The standard categorizes dimensions into key parameters: across flats (A), across corners (B), chamfer (c max), and gauge penetration depth (f). These ensure precise fit with driving tools. See Table 1 for socket number ranges and applications.
| Socket No. Range | Typical Nominal Thread Diameter (mm) | Common Applications |
|---|---|---|
| T1 to T10 | 0.6 to 3 | Electronics, precision instruments |
| T15 to T30 | 3 to 8 | Automotive, consumer goods |
| T40 to T60 | 8 to 16 | Machinery, structural assemblies |
| T70 to T100 | 16 to 30+ | Heavy equipment, aerospace |
This standard specifies hexalobular socket dimensions for indentation diagonal lengths ensuring minimal tool slippage. For sockets outside standard ranges, custom tolerances may apply, increasing uncertainty in fit.
It also includes methods for periodic inspection of gauges and tools to maintain accuracy.
GB/T 6188-2017 is applicable to carbon steel, stainless steel, and alloy fasteners, including those with coatings like zinc plating or passivation. It covers both external and internal drive features but focuses on internal sockets.
For specialized materials or tamper-resistant variants, refer to related standards like GB/T 6188 amendments or ISO equivalents.
GB/T 6188-2017 Standard Overview
Released in 2017 by the Standardization Administration of China, this standard replaces GB/T 6188-2000, incorporating updates for improved precision and international alignment.
It applies to bolts and screws with hexalobular internal drives, specifying dimensions, tolerances, and testing methods for sockets.
Main contents include dimensional tables, gauging requirements, and material considerations for manufacturing.
Basic Principles of Hexalobular Internal Drive
The hexalobular drive features a six-lobed recess that distributes torque evenly, minimizing stress concentrations.
Measurement involves gauging the socket’s across-flats (A) and across-corners (B) dimensions, ensuring compatibility with standard Torx drivers.
The effective torque transmission is calculated based on socket geometry: Torque capacity ∝ (A^3 * material strength). Precise dimensions prevent stripping.
Operational Procedures for Hexalobular Socket Implementation
Procedures for manufacturing and inspecting hexalobular sockets per GB/T 6188-2017.
Manufacturing Environment
Operations typically occur at room temperature (10°C to 35°C). For precision-critical parts, maintain 23°C ±5°C to avoid thermal expansion effects.
Dimensional Specifications
Select socket sizes based on fastener diameter. Table 2 lists key dimensions for various socket numbers.
| Socket No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 15 | 20 | 25 | 27 | 30 | 40 | 45 | 50 | 55 | 60 | 70 | 80 | 90 | 100 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A (Across Corners) | 0.9 | 1 | 1.2 | 1.35 | 1.5 | 1.75 | 2.1 | 2.4 | 2.6 | 2.8 | 3.35 | 3.95 | 4.5 | 5.1 | 5.6 | 6.75 | 7.93 | 8.95 | 11.35 | 13.45 | 15.7 | 17.75 | 20.2 | 22.4 |
| B (Across Flats) | 0.6 | 0.7 | 0.85 | 1 | 1.1 | 1.27 | 1.5 | 1.75 | 1.9 | 2.05 | 2.4 | 2.85 | 3.25 | 3.68 | 4.05 | 4.85 | 5.64 | 6.45 | 8.05 | 9.6 | 11.2 | 12.8 | 14.4 | 16 |
| c (Chamfer Max) | 0.13 | 0.13 | 0.13 | 0.13 | 0.13 | 0.13 | 0.13 | 0.13 | 0.13 | 0.13 | 0.13 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 |
| f (Gauge Penetration Depth) | 0.064 | 0.07 | 0.114 | 0.13 | 0.22 | 0.35 | 0.41 | 0.48 | 0.51 | 0.56 | 0.67 | 0.79 | 0.9 | 1.02 | 1.12 | 1.18 | 1.39 | 1.56 | 1.98 | 2.35 | 2.75 | 3.11 | 3.53 | 3.92 |
Sample Preparation and Requirements
Fasteners must be clean and free of burrs. Use calibrated gauges for inspection.
Equipment includes go/no-go gauges and optical comparators for dimension verification.
Steps: Form socket via cold heading or machining, inspect depths, apply coatings if needed, and verify with torque tests.
Analyze data for tolerance compliance, ensuring A and B dimensions meet nominal values ±0.01 mm for precision grades.
Key Requirements in GB/T 6188-2017
Sockets must withstand specified torque without deformation. Loading involves gradual torque application up to standard limits.
Evaluate dimensions using plug gauges; results must fall within tolerances for acceptance.
Precision is ensured through ISO-class tolerances, with repeatability better than 0.005 mm.
Accuracy and Error Analysis
Errors arise from tool wear, material variability, or measurement inaccuracies.
Improve accuracy by using certified gauges and regular calibration.
Common errors: Oversized sockets leading to slippage—solve by tightening manufacturing controls.
Impact of GB/T 6188-2017 on Industry
Enhances fastener reliability in R&D, reducing failure rates in designs.
Supports quality control by standardizing inspections, ensuring product consistency.
Applications: Automotive engines use T30 sockets for high-torque bolts; aerospace employs T50 for lightweight alloys.
Câu hỏi thường gặp
- What is the difference between hexalobular and hexagonal drives?
- Hexalobular (Torx) provides better torque distribution and cam-out resistance compared to hexagonal (Allen) drives, ideal for automated assembly.
- How to select the appropriate socket size for a bolt?
- Choose based on thread diameter and torque requirements; refer to Table 2 for dimensions ensuring fit without exceeding material limits.
- What are common issues in hexalobular socket manufacturing?
- Issues include inconsistent lobe radii leading to poor tool engagement; mitigate by using precision dies and post-process inspections.
- Is GB/T 6188-2017 compatible with ISO 10664?
- Yes, it aligns closely, allowing interchangeability in global supply chains, though verify tolerances for critical applications.
- What maintenance is required for hexalobular driving tools?
- Regularly inspect for wear on lobes; replace if penetration depth deviates from f values in Table 2 to prevent fastener damage.
- Can hexalobular sockets be used in corrosive environments?
- Yes, with stainless steel or coated fasteners; ensure coatings do not alter socket dimensions beyond tolerances.
