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ASME B107.5M-2002 — Socket Wrenches, Hand (Metric Series)
🔧 ASME B107.5M-2002 is the ASME B107 family standard dedicated to detachable socket wrenches with square drive for hand use (Metric Series). It defines dimensional, performance, and safety requirements for one of the most widely used categories of hand tools in the automotive, machinery, and general maintenance industries. Developed by the ASME B107 Committee (Hand Tools and Accessories), it was approved as an American National Standard on May 13, 2002, superseding the 1994 edition.
💡 The principal change in this edition is the introduction of Type and Class designations in place of the former Class and Style designations, in line with other B107 standards; updated references, finish requirements, and dimensional data are also included.
1. Scope and Overview 📌
Section 1 defines the scope: the Standard provides dimensional, performance, and safety requirements for detachable socket wrenches with square drive for hand use. Notably, inclusion of dimensional data is not intended to imply that all products described are stock production sizes — consumers are requested to consult manufacturers concerning lists of stock production sizes before specifying.
The Standard is supported by a set of normative references including ASME B46.1 (surface texture), ASME B107.4M (driving and spindle ends for portable hand, impact, air, and electric tools), ASME B107.17M (reference gages for wrench openings), plus ASTM B117 (salt spray), B537 (rating of electroplated panels), B571 (adhesion testing), D968 (abrasion resistance), and E18 (Rockwell hardness) — forming a complete material-to-coating-to-test loop.
2. Classification of Sockets 🔩
The Standard groups sockets into two types, with subclasses by length:
- Type I — Sockets: single (6-point) and double (12-point) hexagon openings, available in Class 1 (regular length), Class 2 (long length), and Class 3 (mid length), covering the 6.3 mm, 10 mm, 12.5 mm, 20 mm, and 25 mm square drive series.
- Type II — Universal sockets (block type): single and double hexagon, principally in 6.3 mm, 10 mm, and 12.5 mm drive sizes, for fasteners that are difficult to align squarely.
⚠️ 6-point and 12-point sockets are not freely interchangeable: 12-point sockets have a smaller throat that can catch on hexagonal fastener heads, especially worn or rounded ones; use 6-point sockets for high-torque service.
3. Technical Requirements and Specifications 📏
Multiple tables specify opening dimensions, outside diameters, lengths, square-drive depths, and hexagon mandrel dimensions (including the maximum depth of mandrel insertion) for each drive size, together with requirements for hardness, surface finish, and coating quality. The table below summarizes typical configurations across the drive series:
| Square Drive Size | Approx. Inch | Socket Types Covered | Hexagon Form | Typical Application |
|---|---|---|---|---|
| 6.3 mm | 1/4 in | Type I, Type II universal | 6-pt / 12-pt | Precision and confined-space work |
| 10 mm | 3/8 in | Type I, Type II universal | 6-pt / 12-pt | General automotive and machinery maintenance |
| 12.5 mm | 1/2 in | Type I (incl. long) | 6-pt / 12-pt | General industrial fastening |
| 20 mm | 3/4 in | Type I (long) | 6-pt / 12-pt | Heavy equipment fastening |
| 25 mm | 1 in | Type I (regular) | 6-pt / 12-pt | High-torque, large bolting |
Section 4 (Requirements) states that sockets shall be manufactured from materials that produce tools conforming to the specified physical requirements, properly hardened and tempered, with openings fitting the mandrel; external surfaces shall be free from burrs, cracks, and loose scale, and coatings shall meet the specified abrasion and corrosion tests. The hexagon mandrel dimensions and the maximum depth of mandrel insertion are given to standardize test fixturing.
💡 Table 9 gives hexagon mandrel dimensions and maximum insertion depth; during testing, sockets must be seated to that depth so the torque path is consistent and results are comparable.
4. Test Procedures and Quality Control 🔬
- Hardness test: per ASTM E18 (Rockwell), verifying that heat treatment yields hardness within the specified range.
- Torque (performance) test: with the defined fixture, the socket must withstand the test torque without failure or permanent deformation affecting durability or serviceability.
- Coating tests: plated surfaces are assessed by ASTM B117 salt spray and ASTM D968 falling-abrasive tests for corrosion and wear resistance.
5. Designation and Ordering Notes 📝
Section 6 of the Standard covers designations, giving a consistent way to identify a socket — for example by drive size, opening size, hexagon form, and Type/Class. When writing purchase orders and stock lists, use the full designation string so that a 12.5 mm drive, 19 mm opening, 6-point, regular-length Type I socket is unmistakable, and confirm with the manufacturer that the exact variant is a stock production size. Consistent designation also supports kits and service sets, where sockets of several drives are combined with ratchets, extensions, and universal joints.
6. Engineering Practice Essentials 🛠️
- 🔍 Selection workflow: determine fastener across-flats size and torque → choose 6-pt or 12-pt form → select the drive size that matches the ratchet or breaker bar → pick regular/long/universal variant.
- 🔧 Torque matching: the drive size sets the practical torque ceiling; never extend a small-drive socket with an oversized cheater bar.
- 📊 Universal sockets: torque delivery efficiency drops as the articulation angle increases; correct the applied effort accordingly.
- 📋 Traceability: request a conformance statement and material certificates from suppliers, and review product marking per Section 7.
🚨 Section 7 (Safety Requirements and Limitations of Use) limits these sockets to hand use; they must not be used for impact or overload duty unless the manufacturer expressly states suitability. Apply force smoothly, and retire cracked or distorted sockets immediately.
6. Frequently Asked Questions ❓
❓ Q: What is the difference between B107.5M and B107.1?
A: B107.5M is the Metric Series; B107.1 is the corresponding Inch Series. Both share the same quality, test, and safety framework — the choice depends on the fastener and tooling system in use.
A: B107.5M is the Metric Series; B107.1 is the corresponding Inch Series. Both share the same quality, test, and safety framework — the choice depends on the fastener and tooling system in use.
❓ Q: When should I use 6-point versus 12-point sockets?
A: For undamaged fasteners in confined spaces, 12-point sockets offer easier alignment; for high torque or worn/rounded heads, use 6-point sockets for larger engagement area and slip resistance.
A: For undamaged fasteners in confined spaces, 12-point sockets offer easier alignment; for high torque or worn/rounded heads, use 6-point sockets for larger engagement area and slip resistance.
🔍 Q: Are all sizes listed in the Standard available as stock?
A: Not necessarily — the Standard explicitly notes that dimensional data do not imply stock production sizes; check the manufacturer’s actual production list.
A: Not necessarily — the Standard explicitly notes that dimensional data do not imply stock production sizes; check the manufacturer’s actual production list.
🔧 Q: Can metric sockets be used on inch fasteners?
A: Only if the opening matches the fastener across-flats dimension; mixing systems risks partial engagement and slip, creating a safety hazard.
A: Only if the opening matches the fastener across-flats dimension; mixing systems risks partial engagement and slip, creating a safety hazard.
