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FAQs

Answers to your technical and commercial questions about bigHead fastening products.

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    Closed blind collar

    • Can all bigHead fasteners come with a closed blind collar?

      No. This customisation applies only to F2/SF2 internally threaded collars used with blind Head types B20, B23, B30, B32, B38A and T38A.

    • Do load limits or torque settings change for closed blind collars?

      Standard collar fixing load limits (FLL) and torque recommendations apply. Weld load limits (WLL) may differ and are available on request.

    • How do I calculate the maximum usable thread length (Le)?

      Subtract the unusable length (Lu) from the collar length (L): Le = L – Lu.

    • What are the compatible standard collar lengths for this customisation?

      M4: 10 & 15 mm

      M5 to M8: 10, 15 and 20 mm

      M10 and M12: 15 and 20 mm

    • What is the main advantage of a closed blind collar customisation?

      The blind flange collar design prevents resin or polymer ingress during moulding or composite processing, protecting the thread from blockage and reducing rework.