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ASME B107.35M-1997 — Socket Wrenches, Impact (Inch Series)
🔨 ASME B107.35M-1997 is the standard in the ASME B107 family, Hand Tools and Accessories, that covers detachable impact socket wrenches in the inch (U.S. Customary) series, with opening sizes and square drives expressed in inch units. It is the mirror image of ASME B107.33M-2002, which covers the metric (mm) series: the inch series serves North American and inch-fastener-system markets, while the metric series serves the metric market. Impact sockets are used with electric and pneumatic impact wrenches under high-frequency hammer loads in automotive repair, heavy machinery, steel erection, and assembly lines.
💡 This article is written from domain knowledge of ASME B107.35M. The available copy is a scanned document without a text layer, so the content below follows the general technical requirements of the “Socket Wrenches, Impact (Inch Series)” topic; specific values are subject to the official standard text.
1. Scope and Classification 📌
Corresponding to metric-series B107.33M structure, the inch-series impact sockets are classified by type:
- Type I — Sockets: single hexagon (6-point) and double hexagon (12-point) openings; the 12-point opening fits onto fasteners at smaller rotation angles, while the 6-point provides more reliable face contact and cam-out resistance.
- Type II: reserved.
- Type III — Universal Sockets: with a universal joint for off-angle work.
Square drives are in inch units, typically 1/4 in., 3/8 in., 1/2 in., 3/4 in., and 1 in.; opening sizes are expressed as inch fractions (e.g., 7/16, 1/2, 9/16, 3/4 in.) matching inch-system bolt/nut head across-flats sizes.
| Square Drive | Metric Approx. | Opening Types | Typical Applications |
|---|---|---|---|
| 1/4 in. | 6.3 mm | 6-point / 12-point | Light impact duty, low-torque jobs |
| 3/8 in. | 10 mm | 6-point / 12-point | Medium impact wrenches (most common) |
| 1/2 in. | 12.5 mm | 6-point / 12-point | General repair and assembly work |
| 3/4 in. | 20 mm | 6-point / 12-point | Heavy trucks, suspension, high-torque jobs |
| 1 in. | 25 mm | 6-point / 12-point | Large impact wrenches, heavy industry |
2. Material, Heat Treatment, and Marking Requirements 📏
The technical requirements of the inch-series impact sockets match those of the metric series:
- Materials: the tool material shall be steel, whose chemical composition and heat treatment must meet the specified strength and toughness under impact loading.
- Dimensions: square-drive hole, opening across flats, and depth per the inch data tables; hexagon mandrel dimensions and maximum insertion depth verify the opening fit.
- Marking: sockets must be marked plainly and permanently with the manufacturer’s name or trademark and the nominal opening size (e.g., 1/2 in., 3/4 in.) for traceability and rapid selection.
⚠️ Inch-series openings are marked in inch fractions and must not be approximated with metric series values: for example, a 13/16 in. opening and 21 mm are not the same series, and mixing them selects the wrong size. Procurement and warehousing must strictly separate the two series.
3. Performance Requirements and Test Procedures 🔬
- Proof torque: when loaded to the tabulated torque (in ft·lbf or in·lbf), sockets must not fail or sustain permanent deformation affecting durability or serviceability.
- Hardness: Rockwell hardness per ASTM E 18 to verify heat treatment.
- Finishes: black oxide, phosphate, or plated protective finishes must meet the specified quality for corrosion resistance and wear.
Test procedures include dimensional inspection with gages and mandrels, proof torque loading, Rockwell hardness testing, and finish assessment where applicable, all under the specified conditions.
💡 Fastener systems with inch across-flats heads (trucks, farm equipment, U.S.-market vehicles) require inch-series impact sockets; metric fasteners require the metric series. First identify the fastener system, then the socket series, then the square drive.
4. Engineering Practice and Safety 🛠️
- 🔍 Series matching: select the socket series by fastener system (inch/metric) and the square drive by impact wrench output — both are required.
- 🔧 Never use hand sockets: chrome hand sockets cannot survive impact loads and will shatter; only impact-rated sockets may be used for impact work.
- 📊 Regular inspection: impact sockets fatigue under high-frequency hammering; discard any with cracks, worn or deformed openings, or excessive square-hole wear — never repair by welding and return to service.
- 📋 Protective equipment: wear eye and hand protection during impact work; operators should avoid standing in the direction a failed socket could fly.
🚨 Impact socket failure often has no warning: fatigue accumulates under impact loading, and a surface hairline can be followed quickly by complete fracture. Inspect before every use and stop using at the first doubt — that is the basic safety discipline.
5. Frequently Asked Questions ❓
❓ Q: What is the difference between B107.35M and B107.33M?
A: Both are impact socket standards: B107.35M is the inch series (1/4–1 in. drives, inch-denominated openings) and B107.33M-2002 is the metric series (6.3–25 mm drives, mm openings), serving inch and metric fastener systems respectively.
A: Both are impact socket standards: B107.35M is the inch series (1/4–1 in. drives, inch-denominated openings) and B107.33M-2002 is the metric series (6.3–25 mm drives, mm openings), serving inch and metric fastener systems respectively.
❓ Q: What does the “M” in the designation mean?
A: Some older B107 designations carry an “M” from historical naming. For this Standard the content is the inch series; what matters is the unit system and size tables in the body of the Standard, not the letter in the number.
A: Some older B107 designations carry an “M” from historical naming. For this Standard the content is the inch series; what matters is the unit system and size tables in the body of the Standard, not the letter in the number.
❓ Q: Why are 6-point and 12-point openings both offered?
A: The 6-point (single hexagon) opening contacts the full hex head with the best strength and cam-out resistance; the 12-point (double hexagon) fits in a 30° rotation for restricted positions, at the cost of smaller contact area and slightly lower peak torque.
A: The 6-point (single hexagon) opening contacts the full hex head with the best strength and cam-out resistance; the 12-point (double hexagon) fits in a 30° rotation for restricted positions, at the cost of smaller contact area and slightly lower peak torque.
🔍 Q: How do I tell whether a socket is impact-rated?
A: Impact sockets are typically marked “Impact”, finished black (oxide/phosphate) rather than bright chrome, and have different wall thickness and material grade than hand sockets; also check the cited standard designation (e.g., B107.35M/B107.33M) on the product.
A: Impact sockets are typically marked “Impact”, finished black (oxide/phosphate) rather than bright chrome, and have different wall thickness and material grade than hand sockets; also check the cited standard designation (e.g., B107.35M/B107.33M) on the product.
