CFBSOS Self-Clinching Blind Standoffs (Stainless Steel)
300-series stainless-steel blind self-clinching standoff, passivated to ASTM A967 — pressed flush into sheets from 0.040 in. (1.0 mm) up to Rockwell B-70, unified #4-40 to #10-32 and metric M3 to M5, closed threaded end controlling screw penetration, with per-thread mounting geometry and stainless-standoff performance rows.
Last updated: 2026-11
Specifications
CFBSOS is the 300-series stainless-steel member of the blind self-clinching standoff series: a closed-end standoff that presses flush into a thin panel — no reaming, deburring or welding — and holds a fixed spacing while its internal thread stops the mounting screw at a controlled depth. Passivation is to ASTM A967, so the installed standoff does not add a rusting point to a stainless or corroding environment. The catalog rates CFBSOS for panels of Rockwell B-70 hardness or less — one step stricter than the carbon-steel CFBSO, because the softer standoff needs a softer panel to clinch properly. Most sizes come in two body diameters (small-body 440-style and large-body 6440-style codes). A typical designation reads CFBSOS 6440-10: stainless blind standoff, large body, #4-40, length code -10.
| Series | CFBSOS — 300-series stainless steel, passivated per ASTM A967; installs into panels of Rockwell B-70 hardness or less |
|---|---|
| Threads | Internal 2B per ANSI B1.1 (6H per ANSI/ASME B1.13M for metric): #4-40, #6-32, #8-32, #10-32; M3 x 0.5, M3.5 x 0.6, M4 x 0.7, M5 x 0.8 |
| Minimum sheet thickness | 0.040 in. (1.0 mm) and up |
| Length ladders | Inch .312–1.062 in. (length codes -10 to -34 by thread), tolerance +.002/-.005 in.; metric 6–25 mm (codes -6 to -25), tolerance +.05/-.13 mm |
| Unified geometry, small body (sampled) | #4-40: A .166 +.003/-.000, H .165 +.000/-.005, C .187; #6-32: .213 / .212 / .250; #8-32 and #10-32: .281 / .280 / .312 |
| Unified geometry, large body (sampled) | #4-40: A .213, H .212, C .250; #6-32: .281 / .280 / .312; #8-32 and #10-32: .281 / .280 / .312 |
| Metric geometry (sampled) | M3: A 4.22 +.08/-.00, H 4.2 +.00/-.13, C 4.8; large body 5.41 / 5.39 / 6.4; M3.5: 5.41 / 5.39 / 6.4; M4: 7.14 / 7.12 / 7.9; M5: 7.14 / 7.12 / 7.9 (mm) |
| Trailing minimum columns (sampled) | Two trailing "Min." columns align positionally with the through-series table's minimum-edge-distance and minimum-sheet entries: #4-40 small body .23 in. edge / .040 in. sheet; large body .27 / .040; #6-32 and up .31 / .05; metric M3 6.0 mm / 1.0 mm, M3 large & M3.5 6.8 / 1.0, M4 & M5 8.0 / 1.27 — the printed sub-headers did not survive text extraction (see evidence note) |
| Effective thread depth (blind) | T minimum ladder .156 / .187 / .25 / .375 in. (3.2 / 4.0 / 5.0 / 6.5 / 9.5 mm) across the length ladders; the per-length assignment is not recoverable from the text layer — the metric ladder matches the effective-thread-depth ladder published on the BSO/BSOS/BSOA family page from a second collected source (see evidence note) |
| Part number structure | CFBSOS 6440-10 = series CFBSOS, body code 6 (large body), thread code 440 (#4-40), length code -10; small body uses body code 4 |
| Performance (stainless standoff, .060 in. 5052-H34 aluminum sheet) | 440 group: 1100 lbs installation, 160 lbs pushout, 11 in.-lbs torque-out, 224 lbs pull-through; 6440/632: 1700 / 300 / 25 / 248; 8632/832/1032: 2400 / 400 / 45 / 464 |
| Performance (stainless standoff, .060 in. cold-rolled steel sheet) | 440 group: 2200 lbs installation, 225 lbs pushout, 19 in.-lbs torque-out, 264 lbs pull-through, max tighten 3.8 in.-lbs; 6440/632: 3300 / 420 / 35 / 304 (max tighten 3.8, 7); 8632/832/1032: 4000 / 560 / 75 / 560 (max tighten 7, 14.4, 25.6) |
| MOQ / lead time | Not owner-confirmed for this family — confirmed at quotation |
Materials
- 300-series stainless steel, passivated per ASTM A967 (CFBSOS)
Ordering & documentation
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 (CFBSOS Self-Clinching Blind Standoffs (Stainless Steel)) 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 quantities and lead times for this family are confirmed at quotation — send your sizes, grades and quantities on the RFQ and the quote will carry a firm schedule. Sample availability is confirmed with the 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.
Frequently asked questions
CFBSO or CFBSOS — how do I pick between the two blind steel options?
Let the panel and the environment decide. The catalog maps CFBSO (heat-treated carbon steel, zinc clear) to panels up to Rockwell B-80 and CFBSOS (300-series stainless, ASTM A967 passivated) to HRB 70 or less, so a harder panel points to CFBSO. Where the fastener itself must not rust — outdoor enclosures, washdown, medical or food-adjacent equipment, or a stainless panel where zinc plating would galvanically misbehave — CFBSOS is the pick despite the tighter hardness ceiling. Installation geometry, threads and length ladders are identical between the two; only the material, finish, panel limit and the performance rows differ (stainless pull-through is somewhat lower: 304 vs 380 lbs for the 6440 group in 0.060 in. steel sheet).
What do the performance figures for a CFBSOS include?
The collected catalog's performance table covers all six standoff series and splits by standoff material; the CFBSOS rows are the stainless-standoff rows. In 0.060 in. cold-rolled steel sheet, the large-body #4-40 group (6440) reaches 3300 lbs installation force, 420 lbs pushout, 35 in.-lbs torque-out and 304 lbs pull-through, with a maximum recommended tightening of 7 in.-lbs; in 0.060 in. 5052-H34 aluminum the same group shows 1700 / 300 / 25 / 248. These are tested figures at that sheet thickness for that standoff material — ask for the row of your exact thread, body and sheet at quotation.
What should an RFQ for CFBSOS blind standoffs state?
State the series (CFBSOS 300-series stainless, passivated per ASTM A967), thread size (for example #4-40 or M3 x 0.5), body size (small or large), nominal length L, sheet material, thickness and hardness, and quantity per size — plus destination country. For a blind standoff also state the required effective thread depth and the maximum permitted screw penetration. Commercial terms are confirmed at quotation.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support