FAQs

Designing with bigHead fasteners

• Are torque-out values the same as permissible tightening torque?

  No. Torque-out values reflect rotational failure of the embedded fastener and do not represent the safe tightening torque for installing a nut or screw.

  Tightening torque must be determined separately based on the specific joint design.

• Can I embed standard bigHead collar products directly into SMC?

  We do not recommend this. High moulding pressures can force resin into the thread. Use customised closed blind collar products instead.

• Can I install bigHead fasteners flush in thin discontinuous FRP mouldings (<3 mm)?

  Yes – by using a pocket of at least 3 mm thickness that supports good material flow.

• Can screws pass fully through the laminate when using internally threaded bigHeads?

  Yes – but for sighted (screws pass through) installations, we recommend contacting us first. These cases often require special considerations for configuration geometry, laminate consolidation, and ingress sealing.

• Do reinforced pockets always perform better than unreinforced pockets?

  Reinforced pockets generally offer better load distribution and mechanical performance, especially for pull-out and shear.

  Unreinforced pockets are acceptable where loads are modest or local reinforcement would be complex to implement.

• Do you provide pull‑out strength data for all composite types?

  No. Embedding performance varies widely across FRP material compositions. The guide includes indicative SMC values, but application‑specific testing is required for final validation.

• How do I know if my laminate is thick enough for a flush or inset installation?

  Compare the laminate thickness at the fixing interface with the fastener’s L1 (shoulder/flange) and T (Head) values.

  Flush installations require the laminate thickness to match L1.

  Inset installations require thickness > L1 + T.

• What’s the difference between flush, inset, and socket configurations?

  • Flush → thin sections, low profile.
  • Inset → stronger engagement, moderate thickness.
  • Socket → thick sections, full encapsulation.
• What’s the minimum thickness required for embedding?

  • Flush/inset: typically ≥ 3 mm.
  • Socket: overall fastener length + 1 mm. (e.g. 12.2 mm for M4–M8 closed blind collar products.)
• Which embedment configuration should I choose for my application?

  • Flush works for thin laminates.
  • Inset generally offers higher strength where laminate thickness allows.
  • Pocketed is useful when reinforcement continuity is required.
  • Through configurations suit applications needing a balance of maximised embedment strength with minimum reinforcement/preform disruption.