Hex Key Sizes Chart — Inch Series per ASME B18.3 (0.028 – 3 in Across Flats), Short & Long Series

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 (Hex Key Sizes Chart — Inch Series per ASME B18.3 (0.028 – 3 in Across Flats), Short & Long Series) 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.

How do I match a key to a socket screw, and what does the table tell me about rejecting a worn key?

Match by the socket size the screw standard calls out, not by the screw's nominal diameter: ASME B18.3 socket head cap screws assign the socket (across flats) per screw size, and the key's nominal across-flats must equal it — a 1/4-20 socket cap screw takes the 3/16 in key, while the 3/16 in key size is unrelated to the screw's thread. Where the table earns its keep is deciding whether a key is still good: measure across flats with a micrometer and compare against the printed minimum — a 1/4 in key measuring under 0.2485 in has worn past tolerance and will begin to round the screw's socket corners, and the across-corners minimum (0.2815 in for that size) is the faster tell because corner wear shows first. The short/long series choice is an access decision — the long series reaches recessed sockets at some cost in tip engagement rigidity — and from 1 1/4 in upward the source stops tabulating the long-series pair and prints the bit length instead (flagged). The three smallest sizes print no fraction designation, only decimals (0.028/0.035/0.050 in) — reproduced as printed. What the chart cannot tell you: tool steel grade, hardness and coating of the key — per RFQ.

What is the MOQ and lead time for threaded parts and tooling referenced by this chart?

The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Confirm the exact schedule against quantity, size mix and any tooling items at quotation.