Socket Head Cap Screws
What are Hex Socket Head Cap Screws?
A socket head cap screw is a type of bolt with a hexagonal recess in its head.
It is also commonly referred to as a cap bolt or cap screw.
By inserting a hex key into the hexagonal socket and applying torque across all six sides, the screw can be tightened with high strength and is less likely to loosen.
Compared to using a screwdriver or spanner, it requires less working space, making it suitable for installation in confined areas.
They are widely used in various fields, including industrial equipment and machinery.
The main types include:
1. Socket Head Cap Screws
This is the most common type, featuring a cylindrical head. It is suitable for applications requiring high strength and high torque.
2. Socket Button Head Screws
With a low-profile, rounded head, they are ideal for panels and exterior parts where appearance is important.
In addition, the curved head surface helps suppress electric field concentration at the edges, making them less likely to cause discharge or leakage than cap screws in high-voltage equipment or environments with a risk of discharge
(such as vacuum equipment, electron beam equipment, and X-ray equipment).
3. Socket Flat Head Screws
The flat, countersunk head allows a flush finish with the fastening surface, making them ideal for locations where a protruding head must be avoided.
4. Socket Set Screws (Hollow Set Screws, Grub Screws)
These screws consist only of a threaded section without a head and are used to secure or position components by pressing the tip against a mating part.
Related articles：What are Hex Socket Head Cap Screws (cap bolts)?
Selection Conditions
- Select screw length（mm）4
| Image |  |
 |
 |
|
|
 |
|
|
|
|---|---|---|---|---|---|---|---|---|---|
| Part Name | Socket Head Cap Screws | Socket Head Cap Screws | Hex Socket Head Cap Screws for Precision Instruments (Miniature Screws) | Hex Socket Head Cap Screws for Precision Instruments (Miniature Screws) | Hex Socket Head Cap Screws for Precision Instruments (Miniature Screws) | Hex Socket Head Cap Screws for Precision Instruments | Hex Socket Head Cap Screws for Precision Instruments | Hex Socket Head Cap Screws for Precision Instruments | Hex Socket Head Cap Screws for Precision Instruments |
| Part Number | SNS-M3-4 | SNSS-M3-4 | SNS-M1.6-4 | SNS-M2-4 | SNS-M2.5-4 | SNSS-M1-4 | SNSS-M1.4-4 | SNSS-M1.6-4 | SNSS-M2-4 |
| Feature | Hex Socket Head Cap Screws Conforming to JIS B 1176 |
Hex Socket Head Cap Screws Conforming to JIS B 1176 |
Hex Socket Head Cap Screws for Precision Instruments |
Hex Socket Head Cap Screws for Precision Instruments |
Hex Socket Head Cap Screws for Precision Instruments |
For Precision Instruments | For Precision Instruments | For Precision Instruments | For Precision Instruments |
| Material | Steel | SUSXM7 (Equivalent to SUS304) | Steel | Steel | Steel | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) |
| Thread Size | M3 | M3 | M1.6 | M2 | M2.5 | M1 | M1.4 | M1.6 | M2 |
| Length | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
| Operating Temperature (℃) | - | - | - | - | - | - | - | - | - |
| CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD |
| Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications |
| Image |  |
|
 |
|
|
 |
|
|
 |
|---|---|---|---|---|---|---|---|---|---|
| Part Name | Socket Head Cap Screws with Ultra Low Profile - SUSXM7 | Socket Head Cap Screws with Ultra Low Profile - SUSXM7 | Socket Head Cap Screws with Ultra Low Profile - SUSXM7 - Cleanroom Washed & Packaged | Socket Head Cap Screws with Ultra Low Profile - SUSXM7 - Cleanroom Washed & Packaged | Socket Head Cap Screws with Ultra Low Profile - SUSXM7 - Cleanroom Washed & Packaged | Socket Head Cap Screws with Ultra Low Profile - SUSXM7 - with Nylon Patch | Socket Head Cap Screws with Ultra Low Profile - SUSXM7 - with Nylon Patch | Socket Head Cap Screws with Ultra Low Profile - SUSXM7 - with Nylon Patch | Socket Head Cap Screws with Ultra Low Profile for Sheet Metal |
| Part Number | SSHS-M2.5-4 | SSHS-M3-4 | SSHS-M2-4-UCL | SSHS-M2.5-4-UCL | SSHS-M3-4-UCL | SSHS-M2-4-ALK | SSHS-M2.5-4-ALK | SSHS-M3-4-ALK | SSHS-M3-4-UC |
| Feature | Space-Saving Ultra Low Profile |
Space-Saving Ultra Low Profile |
Space-Saving Ultra Low Profile Cleanroom Washed & Packaged |
Space-Saving Ultra Low Profile Cleanroom Washed & Packaged |
Space-Saving Ultra Low Profile Cleanroom Washed & Packaged |
Space-Saving Ultra Low Profile Nylon Patch |
Space-Saving Ultra Low Profile Nylon Patch |
Space-Saving Ultra Low Profile Nylon Patch |
For Sheet Metal (Plate Thickness 0.1mm or More) Space-Saving Ultra Low Profile |
| Material | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) |
| Thread Size | M2.5 | M3 | M2 | M2.5 | M3 | M2 | M2.5 | M3 | M3 |
| Length | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
| Operating Temperature (℃) | - | - | - | - | - | - | - | - | - |
| CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD |
| Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications |
| Image |  |
|
 |
|
 |
|
|
 |
 |
|---|---|---|---|---|---|---|---|---|---|
| Part Name | Socket Head Cap Screws with Small Head | Socket Head Cap Screws with Small Head | Socket Head Cap Screws with Small Head and Nylon Patch | Socket Head Cap Screws with Small Head and Nylon Patch | Socket Head Cap Screws with Ultra Low Profile - Hastelloy C-22 equiv. | Socket Head Cap Screws with Ultra Low Profile - Hastelloy C-22 equiv. | Socket Head Cap Screws with Ultra Low Profile - Hastelloy C-22 equiv. | Socket Head Cap Captive Screws | Socket Head Cap Captive Screws and Retaining Washer Set |
| Part Number | SNSS-M2-4-SD | SNSS-M2.5-4-SD | SNSS-M2-4-SD-ALK | SNSS-M2.5-4-SD-ALK | SSHH-M2-4-C22 | SSHH-M2.5-4-C22 | SSHH-M3-4-C22 | SSC-M3-4 | SSC-M3-4-SET |
| Feature | Small Head Small Space |
Small Head Small Space |
Small Head Space-Saving Nylon Patch |
Small Head Space-Saving Nylon Patch |
Chemical Resistance Special Low Profile Space-saving |
Chemical Resistance Special Low Profile Space-saving |
Chemical Resistance Special Low Profile Space-saving |
Standard Captive / Loss Prevention |
Standard Captive / Loss Prevention |
| Material | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | Hastelloy equiv. | Hastelloy equiv. | Hastelloy equiv. | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) |
| Thread Size | M2 | M2.5 | M2 | M2.5 | M2 | M2.5 | M3 | M3 | M3 |
| Length | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
| Operating Temperature (℃) | - | - | - | - | - | - | - | - | - |
| CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD | CAD |
| Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications | Specifications |
| Image |  |
 |
|
 |
|
||||
|---|---|---|---|---|---|---|---|---|---|
| Part Name | Socket Head Cap Captive Screws - Cleanroom Washed & Packaged | Vented Socket Head Cap Screws | Vented Socket Head Cap Screws | Vented Socket Head Cap Screws with Small Head | Vented Socket Head Cap Screws with Small Head | ||||
| Part Number | SSC-M3-4-UCL | SVSS-M2-4 | SVSS-M2.5-4 | SVSS-M2-4-SD | SVSS-M2.5-4-SD | ||||
| Feature | Captive/ Loss Prevention Cleanroom Washed & Packaged |
Standard | Standard | Standard Small Head |
Standard Small Head |
||||
| Material | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | SUSXM7 (Equivalent to SUS304) | ||||
| Thread Size | M3 | M2 | M2.5 | M2 | M2.5 | ||||
| Length | 4 | 4 | 4 | 4 | 4 | ||||
| Operating Temperature (℃) | - | - | - | - | - | ||||
| CAD | CAD | CAD | CAD | CAD | CAD | ||||
| Specifications | Specifications | Specifications | Specifications | Specifications | Specifications |
Latest
Helpful Resources
Search by purpose
Product IntroductionCustomizationServices & Product OptionsIssue/case studiesTechnical DataUsageSelection MethodInstallation Method/MaintenanceSafety PrecautionsGlossary
Search by keyword
Improved productivity/workabilitySafety measures/precautionary measuresReduced cost/energy saving/long lifeVibration prevention/high precisionCompact/space-saving/lightweightCustomizationHigh strength/high rigidityHeat resistance/corrosion resistanceElegant functionality/designCleanroom/vacuum/non-magneticSeizing PreventionAutomation/robots/motorizationOthers
Search by industry
Machine ToolsSemiconductor Manufacturing EquipmentFood MachineryAutomotive Manufacturing ProcessMedical equipmentFA Devices
Search by series
The Semiconductor Industry and NBKVideo LibraryHints for correctly using NBK productsSolution samplesWhat is a Screw?Description of Mechanical Components for EngineersDescription of Special Screws for Engineers3 Min Engineering TipsServices & Product OptionsTechnical Data
