A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70) is the most common stainless group for indoor and general outdoor fasteners. When cage nuts (snap-in rack nuts) are specified in this grade, the dimensions remain per Trade series (EIA-310 rack practice); the material determines corrosion behavior (good general corrosion resistance) and the service temperature range (approx. -200 °C to +400 °C, subject to the property class and the joint). Both are covered below with the size table.
Why Choose A2 Stainless Steel for Cage Nuts (Snap-In Rack Nuts)
The most common stainless group for indoor and general outdoor fasteners. For cage nuts (snap-in rack nuts), this matters when good general corrosion resistance is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Good general corrosion resistance |
Galvanic & Galling Considerations
Two important notes for stainless cage nuts (snap-in rack nuts): (1) stainless can gall on stainless threads under load — use a thread lubricant or anti-galling compound, especially for M6 and below; (2) when joined to aluminum or galvanized steel, stainless can drive galvanic corrosion of the less-noble metal in wet service — isolate with a coating or sleeve where appropriate.
Comparable Grades
For Cage Nuts (Snap-In Rack Nuts), the alternative stainless grade is A4 (316). The practical dividing line is chlorides: A2 (304) is fine until salt is involved, and A4 (316) exists for the cases where it is — coastal, marine and road-salt service. Neither reaches the strength of a plated class 8.8 or 10.9 fastener.
Using Stainless Fasteners in Aluminum
Expect the aluminum to corrode, not the fastener — stainless sits higher in the galvanic series, so the aluminum is the one that gives up material. A small fastener in a thick section spreads the loss over a large area and is usually fine; a large fastener in thin sheet concentrates it and is not. Keep water out of the joint, or isolate the two metals with a nylon or coated washer and a sealant.
Sizes of Cage Nuts (Snap-In Rack Nuts) Available in A2 Stainless Steel
| Thread size | Square panel hole (mm) | Rail thickness (mm) | Cage width (mm) | Cage height (mm) | Retained nut | Material | Finish |
|---|---|---|---|---|---|---|---|
| M5 | 9.5 | 0.8~2.0 | 15.9 | 15.9 | Floating square | Spring steel | Zinc plated |
| M6 | 9.5 | 0.8~2.0 | 15.9 | 15.9 | Floating square | Spring steel | Zinc plated |
| M6 | 9.5 | 2.0~3.0 | 15.9 | 15.9 | Floating square | Spring steel | Black passivated |
| 10-32 | 9.5 | 0.8~2.0 | 15.9 | 15.9 | Floating square | Spring steel | Zinc plated |
| 12-24 | 9.5 | 0.8~2.0 | 15.9 | 15.9 | Floating square | Spring steel | Zinc plated |
| M8 | 12.0 | 1.0~2.5 | 19.0 | 19.0 | Floating square | Spring steel | Zinc plated |
