Fine Pitch Socket Head Cap Screws (Metric Fine)
Engineered for applications demanding superior vibration resistance and precise adjustment, these Fine Pitch Socket Head Cap Screws (SHCS) address the limitations of standard coarse threads. By utilizing a smaller thread pitch and a lower helix angle, these fasteners significantly reduce the likelihood of self-loosening in dynamic environments such as automotive powertrains and high-speed machinery. Furthermore, the increased minor diameter of the fine thread profile yields a larger tensile stress area, allowing for higher clamp loads in critical assemblies where failure is not an option.
- Resists vibrational loosening (Low helix angle).
- Higher static tensile strength than coarse threads.
- Precise fine-tuning adjustment capabilities.
- Class 12.9 Alloy Steel (1200 MPa).
- Optimized for thin-walled tapping applications.
- Strict DIN 912 / ISO 4762 dimensional tolerance.
Technical Specifications
Product Name
Fine Pitch Socket Head Cap Screw (SHCS)
Standards
DIN 912, ISO 4762 (Metric Fine Series)
Material Grades
Alloy Steel: Class 10.9, Class 12.9 (Standard Supply)
Stainless Steel: A2-70, A4-80 (Upon Request)
Drive Type
Hex Socket (Allen)
Thread Type
Metric Fine (MF) – 6g Tolerance
Pitch Options
M8x1.0, M10x1.0, M10x1.25, M12x1.25, M12x1.5, etc.
Surface Finish
Black Oxide (Thermal), Zinc Plated (Cr3+), Zinc Flake (Geomet)
Certifications
EN 10204 3.1 Material Certificate Available
Why Specify Fine Pitch over Coarse Pitch?
Combating Vibration & Self-Loosening:
The primary failure mode in dynamic machinery is the loss of preload due to vibration. Fine pitch threads possess a smaller helix angle compared to coarse threads. This geometry creates greater friction at the thread interface and significantly reduces the tendency of the screw to “back out” under cyclic loading. This often eliminates the need for additional locking mechanisms like chemical patches or lock washers.
Increased Tensile Strength:
Because the threads are shallower, the minor diameter (root area) of a fine pitch screw is larger than that of a coarse pitch screw of the same nominal size. This results in a larger tensile stress area (As), enabling the fastener to withstand higher static loads without yielding.
Precision Adjustment:
In applications such as optical calibration rigs or micrometer setting devices, the smaller pitch (advance per revolution) allows for finer axial positioning control, essential for high-precision engineering.
Note: Fine pitch series often have multiple pitch options for a single diameter. Ensure you verify the specific pitch required (e.g., M10x1.0 vs M10x1.25).
| Thread Size (d) | Fine Pitch (P) | Head Diameter (dk) | Head Height (k) | Socket Width (s) |
| M8 | 1.00 mm | 13.00 mm | 8.00 mm | 6.0 mm |
| M10 | 1.00 / 1.25 mm | 16.00 mm | 10.00 mm | 8.0 mm |
| M12 | 1.25 / 1.50 mm | 18.00 mm | 12.00 mm | 10.0 mm |
| M14 | 1.50 mm | 21.00 mm | 14.00 mm | 12.0 mm |
| M16 | 1.50 mm | 24.00 mm | 16.00 mm | 14.0 mm |
| M20 | 1.50 / 2.00 mm | 30.00 mm | 20.00 mm | 17.0 mm |
Assembly Protocols for Fine Threads
Cross-Threading Prevention:
Fine threads are more susceptible to cross-threading (galling) during initial engagement than coarse threads. Hand-start the fastener for the first 2-3 full turns before applying any power tools. This is critical when installing into dissimilar metals like aluminum or cast iron.
Cleanliness is Critical:
The tighter thread clearance means debris, plating buildup, or old threadlocker can cause significant interference. Ensure tapped holes are cleaned with a chaser tap if necessary to ensure the applied torque translates to preload, not friction.
Torque Settings:
Due to the larger stress area, Fine Pitch Class 12.9 screws can often accept higher torque values than their coarse counterparts. Consult VDI 2230 standards to calculate the precise tightening torque based on your specific friction coefficient (u).
Related Products
FAQ
Why use fine pitch socket screws instead of coarse pitch?
Fine pitch screws are used primarily for their superior resistance to vibration loosening and higher tensile strength. The lower helix angle increases friction at the thread interface, preventing back-off, while the larger minor diameter provides a greater cross-sectional area for bearing loads.
Are DIN 912 fine thread screws interchangeable with standard ones?
No, fine thread (Metric Fine) and coarse thread (Metric Coarse) screws are not interchangeable. While the head dimensions (dk, k, s) are usually identical, the thread pitch is different. Attempting to force them will destroy the threads of both the screw and the tapped hole.
What is the most common material for Fine Pitch SHCS?
Class 12.9 Alloy Steel is the industry standard for Fine Pitch SHCS. Engineers typically select fine threads for high-stress applications, so the material grade must match the high-performance requirement. Stainless steel (A2/A4) is available but less common due to the high risk of galling in fine stainless threads.
How do I measure the pitch of a screw?
Use a thread pitch gauge. In the metric system, pitch is the distance in millimeters between the crest of one thread and the next. For example, an M10 Coarse screw has a 1.5mm pitch, while an M10 Fine screw usually has a 1.0mm or 1.25mm pitch.
Are fine pitch screws better for tapping into thin materials?
Yes. Fine pitch screws have a smaller thread depth, allowing for more full threads of engagement in thin-walled tubes or sheets. This distributes the clamp load more evenly and reduces the risk of stripping the tapped hole compared to a coarse thread.