Bolt & Sleeve Anti-Loosening Fasteners

Maximizes performance in joints that must accommodate expansion and contraction due to creep and in-service load relaxation.

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Thermal expansion, creep and material relaxation cause application materials to expand or contract. These dimensional changes can result in the loss of clamp in the joint members. A bolt that can accommodate these changes while maintaining the integrity of the application is needed.

The design of the bolt and sleeve assembly by Acument® maximizes fastening performance in these applications while minimizing in-place costs.


  • Cold formed bolt with roll-formed threads
  • Captivated sliding sleeve with resilient grommet
  • Bolt/sleeve meet strength levels up to P.C.10.9
  • Custom-engineered to desired compression load and distance requirements
  • Manufacturing method minimizes damage to grommet


  • Accommodates vertical movement of joint components caused by in-service conditions, including load relaxation and thermal expansion
  • Can be used with nonparallel joint surfaces
  • Minimizes damage to the top surface of the joint
  • Accommodates tolerance variations in components
  • Engineering changes in sleeve length easily and quickly accommodated
  • No added costs for tooling changes for varying sleeve lengths
  • No special tooling required for installation

Design Guidelines

  • Fastener Sizes: M4 – M12; lengths and washer sizes as required by application
  • Head Styles: as required
  • Thread Styles: as required
  • Drive System: TORX PLUS® Drive, external hex; others available upon request
  • Point Options: dog point, header point, Acupoint® feature; others as required
  • Materials: low carbon steel; others available upon request