A4 Stainless Steel Knurled Thumb Screws, Low Type are supplied to DIN 653. The grade provides superior, including marine and chloride environments and is largely non-magnetic; the practical service range is approx. -200 °C to +400 °C, subject to the property class and the joint. Property data, grade comparison and the full size table follow.
Why Choose A4 Stainless Steel for Knurled Thumb Screws, Low Type
Specified for marine, coastal and chemical applications. For knurled thumb screws, low type, this matters when superior, including marine and chloride environments is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80 |
|---|---|
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Superior, including marine and chloride environments |
Corrosion Behavior in Service
A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For Knurled Thumb Screws, Low Type in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.
Galvanic & Galling Considerations
Two important notes for stainless knurled thumb screws, low type: (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.
Using Stainless Fasteners in Aluminum
Stainless steel is more noble than aluminum, so with an electrolyte present — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. Area ratio decides how bad it gets: a small stainless fastener in a large aluminum section is normally acceptable, a large stainless fastener in thin aluminum is not. Where the joint gets wet, isolate the metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.
Sizes of Knurled Thumb Screws, Low Type Available in A4 Stainless Steel
| Size | a_max (mm) | c (mm) | Head diameter dk (mm) | dk_max (mm) | dk_min (mm) | ds_nom_max (mm) | ds_min (mm) | e (mm) | Head height k (mm) | k_min (mm) | r (mm) | Knurling | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M1 | 0.75 | 5.5 | 5.74 | 5.26 | 1.5 | 1.25 | 0.5 | 0.5 | 2~6 | DIN 653 | ||||
| M1.2 | 0.75 | 6 | 6.24 | 5.76 | 1.5 | 1.25 | 0.5 | 0.5 | 2~8 | DIN 653 | ||||
| M1.4 | 0.9 | 7 | 7.29 | 6.71 | 2 | 1.75 | 0.5 | 0.5 | 3~10 | DIN 653 | ||||
| M1.6 | 1.05 | 7.5 | 7.79 | 7.21 | 2 | 1.75 | 0.5 | 0.5 | 3~12 | DIN 653 | ||||
| M2 | 1.2 | 9 | 9.29 | 8.71 | 2 | 1.86 | 1.5 | 2 | 1.75 | 0.5 | 0.5 | 4~16 | DIN 653 | |
| M2.5 | 1.35 | 0.3 | 11 | 11.35 | 10.65 | 2.5 | 2.36 | 2 | 2.5 | 2.25 | 0.5 | 0.6 | 5~18 | DIN 653 |
| M3 | 1.5 | 0.3 | 12 | 12.35 | 11.65 | 3 | 2.86 | 2 | 2.5 | 2.25 | 0.5 | 0.6 | 6~20 | DIN 653 |
| M4 | 2.1 | 0.4 | 16 | 16.35 | 15.65 | 4 | 3.82 | 3 | 3.5 | 3.2 | 0.5 | 0.6 | 8~25 | DIN 653 |
| M5 | 2.4 | 0.4 | 20 | 20.42 | 19.58 | 5 | 4.82 | 3 | 4 | 3.7 | 1 | 0.6 | 10~30 | DIN 653 |
| M6 | 3 | 0.5 | 24 | 24.42 | 23.58 | 6 | 5.82 | 4 | 5 | 4.7 | 1 | 0.6 | 12~30 | DIN 653 |
| M8 | 3.75 | 0.6 | 30 | 30.42 | 29.58 | 8 | 7.78 | 5 | 6 | 5.7 | 2 | 0.6 | 16~35 | DIN 653 |
| M10 | 4.5 | 0.8 | 36 | 36.5 | 35.5 | 10 | 9.78 | 6 | 8 | 7.64 | 2 | 0.6 | 20~40 | DIN 653 |
Dimensions are independent of the material: every size above is available in A4 Stainless Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
A4 Stainless Steel is one of the grades the catalog describes. Dimensions, material, finish and form are specified from the drawing — a screw outside the standard range is a variation on existing tooling rather than a new design. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
