Wrench Openings Table (Nut Across Flats, Jaw Allowance, Nut Sizes Served)

Documents

Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.

Quotation

• The fastener family (Wrench Openings Table (Nut Across Flats, Jaw Allowance, Nut Sizes Served)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
• Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
• Quantity per size and your target delivery date.
• Destination country, and any required documents (for example a mill test certificate) so the quote includes them.

Sample & supply

Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.

Storage & shipping

Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.

Why do the allowance and tolerance grow with wrench size — and what does that mean for a worn wrench?

Because the fit is functional looseness, scaled: the opening must slip over a nut at max across-flats without forcing, and manufacturing variation grows with absolute size, so the system budgets 0.002 in at 5/32 and 0.035 in at 6-1/8. The numbers in the middle of the table show the budget is tight in percentage terms — at 1/2 in the opening is 0.504 +0.006, so about one percent of total play. Wear consumes exactly that budget: an open-end that has spread 0.010 in past nominal is at or past the tolerance ceiling at mid sizes, and the load then sits on the hex corners instead of the flats — which is how a properly sized wrench rounds a nut. The inspection rule the table supports is simple: check opening max against the tabulated figure with a gauge pin; anything beyond the +tolerance column is a rounding risk at torque, whatever the brand on the handle.

Why does heavy hex need a different wrench size than standard hex at the same bolt size?

Because heavy series across-flats are larger by design — more nut height and more flat width to carry higher preload and resist thread stripping — and table 2 encodes the consequence: the heavy columns (Heavy Square, Heavy Hex and its jam/flat variants) land on the next wrench basic size up from the standard hex column at the same nominal bolt. A 1/2 in standard hex runs 3/4 across flats; the heavy hex at the same nominal takes the 7/8 opening. That is a real site cost — mixed standard/heavy assemblies need both wrench sizes staged — and a real safety note: forcing a standard-size wrench onto a heavy nut (or trusting a "close enough" adjustable at the wrong end of its scale) starts the corner-rounding failure mode the tolerance table exists to prevent. Order hardware and tooling so the heavy-series rows are matched with the heavy wrench size at issue time.