Captar nut retainers are spring steel components designed to hold a captive nut or threaded insert firmly in place within a plastic or sheet component. They bridge the gap between rigid fastening and flexible assembly by ensuring the nut remains located, doesn’t rotate, and is protected from dislodgement during handling or vibration. In assemblies where threaded inserts or nuts are needed but cannot be permanently fixed by moulding or welding, Captar nut retainers provide a reliable mechanical retention method.
Advantages
- No risk of thread splitting or embrittlement
- Thread conforms to relevant British Standard
- Easily replaceable
- Fast assembly
Method of Assembly
Simply push compression ring over split knob end and then push whole assembly over shaft.
When specifying, please state:
- Quantity
- Prefix (CBCC)
- Part No.
- Finish code (e.g. 1000 CBCC-1034-13)
How They Work & Key Functions
- Captar nut retainers grip the nut or insert via spring tension, tabs, or slots, holding it axially or radially in place.
- The retainer is itself clipped, snapped, or embedded into a plastic housing or sheet so that the nut is captive but can accept a screw from either side.
- During assembly, the screw engages the captive nut without displacing it. The retainer ensures alignment, prevents rotation, and maintains the nut’s position.
- The spring steel nature of Captar retainers gives them resilience — they can flex slightly while maintaining grip, which accommodates tolerance variations or misalignment.
Design & Application Guidelines
Nut & Retainer Selection
Choose retainer geometry that matches the nut’s shape (hex, square, round) to maximize contact and restraint.
Ensure the retainer holds the nut firmly but does not deform its threads during clamping.
Housing / Plastic Integration
Provide adequate clearance and access in the housing or pocket for insertion of the retainer + nut.
Use local bosses, ribs, or recesses to stabilize the retainer and prevent side movement or rotation.
Material & Coating
Use spring steel with appropriate surface finishes (e.g. zinc, phosphate) to reduce corrosion and wear against plastic.
Ensure the retainer finish is compatible with surrounding materials and assembly environment (temperature, humidity, chemicals).
Tolerance & Fit Control
Allow slight radial clearance to accommodate thermal expansion but maintain sufficient grip.
Avoid overly tight fits that force the retainer and nut apart or damage the plastic housing.
Assembly / Handling
- Insert the retainer + nut with a controlled press or snapping operation.
- Avoid misalignment during insertion to prevent bending retainer legs.
- During service, the captive nut should remain stable and resist rotation or backing out while the screw is torqued.
Dimensional Data & Sizes
Dimensions in millimetres
Enhance Your Assembly with Our Captar Nut Retainers
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