Date Updated:May. 16. 2025
What are Captive Screws? Introduction of the NBK Captive Series
What are Captive Screws?
Captive screws feature a relief cut in the threads to prevent them from dropping out. The design ensures that the screw remains attached to the cover, even when detached from the frame.
NBK offers a standard product line of captive screws and other components designed to prevent machine parts from falling off.
CE Marking
The CE marking (CE mark) indicates a manufacturer's compliance with the EC Directives for products such as industrial machinery and equipment.
Products exported or distributed within EU member states must comply with the EC Directives. Consequently, CE marking is mandatory for circulation within EU member states to demonstrate compliance.
Under Regulation (EU) 2023/1230, Annex III (formerly Directive 2006/42/EC, Annex I), screws used to secure guards or access panels must must not fall out of the cover when it is removed.
Excerpt from Regulation (EU) 2023/1230, Annex III
- 1.4.2 Special Requirements for Guards
- Item 1.4.2.1 Fixed Guards
- Fixed guards must be fixed by systems that can be opened or removed only with tools.
- Their fixing systems must remain attached to the guards or to the machinery when the guards are removed.
- Where possible, guards must be incapable of remaining in place without their fixings.
- PART A Definitions
- (f) ‘guard’ means a part of the machinery used specifically to provide protection by means of a physical barrier.
Types and Features of CE Marking Compliant
Captive Screws
These screws are designed to remain attached to the cover, even when the cover removed from the frame, due to a structure that engages with the cover's screw hole.
Retaining Washers
Socket Head Cap Captive Screw/Washer Sets
These sets combine captive screws and washers, as previously described. The captive screw is designed to engage with the cover's screw hole, preventing both screw fall-off and loss, even if the washer is damaged.
CE Marking Compliant Product
Screw| Material |
Surface Treatment |
Screw Head Shape | ||||||
|---|---|---|---|---|---|---|---|---|
| Cap | Low Profile | Ultra Low Profile | Hexagon | Pan Head Machine Screws | Button | Truss | ||
| SUS | － | SSC SSC(INCH) SSC-UCL |
SSCLS | SSCHS | SSC-SNHS | SSCPS | SSC-SRBS | SSCMS |
| SSCZS | ||||||||
| Low-Temperature Black Chrome Plating | SSC-RY | － | － | － | － | － | － | |
| Fluorine | SSC-FC | |||||||
| PTFE | SSC-TF | |||||||
| SUS316L | － | SSC-SNSLG | － | SSC-SLHL | SSC-SNHL | SSCPL | － | SSCML |
| SSC-SNSL | ||||||||
| SCM435 | Electroless Nickel Plating | SSC-SNS-EL | － | － | － | － | － | － |
| TW340 (Grade 2 Titanium) |
－ | SSC-SNST | － | － | － | － | － | － |
| Ti-6Al-4V (Grade 5 Titanium) |
－ | SSC-SNSTG | － | － | － | － | － | － |
Types and Features of Captive Series
Captive Knobs
Captive knobs are designed to remain attached to the cover, even when the screw is removed from the frame, due to a structure that engages with the cover's screw hole.
Captive Pulls
Even when the nut is loosened, the pull and nut are designed to remain temporarily engaged with the relief cut, preventing accidental falls.
For Captive Pull UNMS-SC
For Pull without Captive Mechanism
Captive Washers for Pulls
These washers provide a clean, decorative finish on pull mounting surfaces while preventing pull mounting screws from falling out.
Captive-Design Product
Knob| Material | Surface Treatment | Captive Processing |
|---|---|---|
| Steel | Chrome Plating | KNM-SC |
| KUM-SC | ||
| SUS | － | KNMS-SC |
| KNML-SC | ||
| KUMS-SC | ||
| KWBS-SC | ||
| Knob：Nylon6 Screw：SUS |
－ | KDMS-SC |
Handle
| Material | Surface Treatment | |
|---|---|---|
| SUS | － | UNMS-SC |
| LYSC-N-SSC |
Washers
| Material | Surface Treatment | |
|---|---|---|
| SUS | － | LYSC-N |
| LYSC-N-SSC |
Captive Processing Service
e-nedzi.com offers custom screws with relief-cut screws and integrated fall prevention features.
See here for details on the captive processing service ＞＞
Custom Captive Screws
We design and manufacture captive screws to meet specific application requirements, including shape, dimensions, and materials.
For large-scale production inquiries, please contact our customer service.
Inquiries about special products including captive screws
For others inquiries, please contact us here
