NBK logo

Date Updated:May. 16. 2025

What are Captive Screws? Introduction of the NBK Captive Series

CE Marking Compliance and Contamination Control

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.

SWAS-SC_usage_en

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


Washers
Material Surface Treatment
SUS  SWAS-SC


Double anti-loosening mechanism (screw + washer)
Material Surface Treatment
SUS  SSC-SET


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

en_captiveseries-1

For Pull without Captive Mechanism

en_captiveseries-2

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

Product Introduction Improved productivity/workability Safety measures/precautionary measures Machine Tools Semiconductor Manufacturing Equipment Food Machinery Automotive Manufacturing Process Medical Equipment FA Devices Special Screws Machine Elements