Property Class 12.9 Steel Micro Small Countersunk Phillips Machine Screws are supplied to ISO 898-1 property class 12.9. Corrosion behaviour is requires plating or black-oxide protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the highest common strength class, for high-load machine assembly.
- Grade
- ISO 898-1 property class 12.9
- Corrosion resistance
- Requires plating or black-oxide protection
- Magnetic response
- Magnetic
- Service temperature
- commonly limited to approx. +300 °C; confirm against the coating and the load
Property values are typical for the grade. Certified mechanical test data is available on request for production orders.
Property Class 12.9 Steel Micro Small Countersunk Phillips Machine Screws are supplied to our own published dimensions — this is a trade-series article rather than one covered by a dimensional standard, so confirm the figures against the part you are replacing. The grade provides requires plating or black-oxide protection and is magnetic; the practical service range is commonly limited to approx. +300 °C; confirm against the coating and the load.
Why Choose Property Class 12.9 Steel for Micro Small Countersunk Phillips Machine Screws
The highest common strength class, for high-load machine assembly. For micro small countersunk phillips machine screws, this matters when requires plating or black-oxide protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 12.9 |
|---|
| Magnetic response | Magnetic |
|---|
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
|---|
| Corrosion characteristic | Requires plating or black-oxide protection |
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Galvanic & Galling Considerations
For micro small countersunk phillips machine screws in steel, the dominant compatibility issue is hydrogen embrittlement at high property classes (10.9 and above) when electroplated. Plating must be followed by an appropriate baking treatment, or a non-electroplated finish (mechanical zinc, zinc flake) should be substituted.
Comparable Grades
For Micro Small Countersunk Phillips Machine Screws, class 8.8 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.
Sizes of Micro Small Countersunk Phillips Machine Screws Available in Property Class 12.9 Steel
| Thread size | Head diameter (mm) | Head height (mm) | Typical length range (mm) | Countersink angle (deg) | Material options |
|---|
| M1.4 | 2.0 | 0.45 | 2~20 | 90 | steel / A2 or 316 stainless / brass |
| M1.6 | 2.4 | 0.50 | 2~20 | 90 | steel / A2 or 316 stainless / brass |
| M1.7 | 2.5 | 0.50 | 2~20 | 90 | steel / A2 or 316 stainless / brass |
| M2.0 | 3.0 | 0.60 | 2~20 | 90 | steel / A2 or 316 stainless / brass |
| M2.3 | 3.5 | 0.70 | 2~20 | 90 | steel / A2 or 316 stainless / brass |
| M2.5 | 3.8 | 0.80 | 2~20 | 90 | steel / A2 or 316 stainless / brass |
| M2.6 | 4.0 | 0.80 | 2~20 | 90 | steel / A2 or 316 stainless / brass |
Dimensions are independent of the material: every size above is available in Property Class 12.9 Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
Grade 12 9 Steel is one of the grades the catalog describes. Lengths and thread lengths outside the standard table are the commonest request, followed by a drive the standard does not offer and a head marked with your own part number. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom screw manufacturingSend a drawing
Applications & Industries
Micro Small Countersunk Phillips Machine Screws are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from M1.4 to M2.6.
Industries that specify Micro Small Countersunk Phillips Machine Screws
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Microfabrication
The head angle and diameter are checked against the prepared countersink.
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Precision electronics
Countersunk heads leave miniature covers flush where a projecting head would interfere.
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Optical instruments
Small flush screws hold frames and retainers in a narrow envelope.
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Instrument repair
Short lengths suit thin brackets and fine housings.
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Energy & infrastructure
Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.
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Maintenance & MRO
Stocked replacements matched to an existing property class, thread and finish.
Typical applications
- using the correct small cross driver
- seating a miniature screw flush in a countersunk hole
- matching the 90-degree seat to the parent part
- selecting a length that does not bottom in a blind tapped hole
- joints where the property class is stated on the drawing
- clamping two machined faces to a calculated preload
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Torque and preload
- The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.
Where to use something else
- Do not force a countersunk head into a flat or undersized seat; the thin parent part can crack or dish.
- Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.
Full application guide: where Micro Small Countersunk Phillips Machine Screws are used, how to specify them, and the cases they are wrong for
