Product Description
2-56 UNC A2 Stainless Steel Pan Phillips Head Machine Screws
These 2-56 UNC machine screws are manufactured from A2 stainless steel and feature a conventional pan head with an internal Phillips drive. Their small diameter makes them suitable for electronics, instruments, model engineering and other compact assemblies requiring an imperial machine screw.
The No.2 Unified National Coarse thread has 56 threads per inch and a nominal major diameter of 0.086 inches, approximately 2.18mm. These screws must be used with a matching 2-56 UNC nut or internally threaded component.
Available in a 1/4 inch length and pack quantities ranging from 5 to 1,000.
Key Features
- 2-56 UNC imperial machine screw thread
- 56 threads per inch
- Nominal thread diameter of 0.086 inches
- A2 stainless steel construction
- Rounded pan head with a flat bearing surface
- Internal Phillips cross recess
- PH1 driver size
- Suitable for matching 2-56 UNC nuts and tapped holes
- Available in packs from 5 to 1,000
Available Length
| Thread Size | Threads Per Inch | Imperial Length | Approximate Metric Length |
|---|---|---|---|
| 2-56 UNC | 56 TPI | 1/4" | 6.35mm |
Machine screw length is measured from beneath the pan head to the end of the threaded section.
Nominal Dimensions
| Thread Designation | 2-56 UNC |
|---|---|
| Nominal Thread Diameter | 0.086" / approximately 2.18mm |
| Thread Pitch | 56 TPI / approximately 0.454mm |
| Reference Head Diameter | Approximately 0.154–0.167" / 3.91–4.24mm |
| Reference Head Height | Approximately 0.053–0.062" / 1.35–1.57mm |
| Recommended Driver | PH1 Phillips driver |
Head dimensions are reference values for standard No.2 pan head machine screws. Confirm the dimensions of the supplied product before use where head clearance or recess size is critical.
Thread Identification
The 2-56 designation identifies a No.2 diameter screw with 56 threads per inch. UNC means Unified National Coarse, with 56 TPI being the standard coarse thread for a No.2 machine screw.
These screws are not interchangeable with 2-64 UNF machine screws. Both have the same nominal diameter, but the 2-64 UNF version has a finer 64 TPI thread.
They are also not interchangeable with metric M2 or M2.2 fasteners. Although the diameters may appear similar, the thread pitches and profiles are different.
Standards Information
- ASME B1.1 covers Unified inch screw threads, including the 2-56 UNC thread form.
- ASME B18.6.3 covers inch-series machine screws and associated recessed pan head styles.
- BS 1981:1991 covers unified machine screws and machine screw nuts, including No.2 recessed pan head machine screws.
No directly applicable DIN standard has been assigned because this is an inch-series UNC machine screw rather than a metric DIN product.
These standards are provided as dimensional and thread-form references for the product type. Confirm manufacturer certification, tolerances and material documentation before specifying the screws for standards-controlled applications.
A2 Stainless Steel
A2 stainless steel provides good corrosion resistance for general indoor use and many outdoor environments. It is commonly selected for equipment, electrical assemblies and engineering applications where an unplated, corrosion-resistant finish is preferred.
For coastal, marine, swimming-pool or chloride-rich environments, an appropriate A4 stainless steel fastener may provide improved corrosion resistance. Suitability should be assessed for the particular operating environment.
Typical Applications
- Electronics and circuit-board assemblies
- Instrument housings and control equipment
- Small electrical enclosures
- Model engineering and radio-controlled models
- American-manufactured equipment
- Precision brackets and miniature mechanisms
- Restoration and repair work
- Small covers and access panels
Installation Advice
Confirm that the mating nut or tapped hole has a 2-56 UNC thread. Use a correctly fitting PH1 Phillips driver and apply light, controlled pressure to reduce cam-out and damage to the small screw head.
Take care not to overtighten miniature machine screws or damage the mating thread. Stainless steel threads can also gall or seize, so a suitable anti-galling compound may be helpful where the assembly will require future maintenance.
Useful Links
- View all UNC A2 stainless pan Phillips machine screws
- View all machine screws
- 4-40 UNC A2 stainless pan Phillips machine screws
- 6-32 UNC A2 stainless pan Phillips machine screws
- 8-32 UNC A2 stainless pan Phillips machine screws
- 10-24 UNC A2 stainless pan Phillips machine screws
- 2-56 UNC A2 stainless countersunk Phillips machine screws
- Metric, UNC, UNF and BSP thread data guide
- How to measure a bolt or screw
- Stainless steel thread galling prevention guide
Specifications are intended as a guide. Confirm the stainless grade, head dimensions, thread tolerances and certification before use in safety-critical or specification-controlled applications.
