• Advanced shimming for enhanced throughput

    Advanced shimming for enhanced throughput banner
    3M has partnered with Airbus on liquid shim to help aircraft production efficiency soar.

    Among the many complex processes involved in aircraft production and assembly, shimming composite structures can be disproportionately labor intensive. Liquid shim solutions from 3M, developed in collaboration with Airbus, can eliminate the need to measure gaps. They have helped the A350 wing assembly team save thousands of man hours and significantly reduce costs per wingset.

    • Graphic of a liquid shim application.

      Shimming in aircraft production

      A shim is a thin piece of material used to fill gaps in bolted joints. In aircraft production and assembly, shims may be added to rib-to-wing cover and other load-bearing aerostructure applications to help absorb tolerance mismatch and reduce build stresses. An aircraft may require thousands of shims to maintain optimal structural performance.

      Shimming composite structures, such as A350 composite wings, can be disproportionately labor intensive. Due to higher tolerances in certain large composite structures, when compared to metal, gaps can be a broad range of shapes and sizes. Gaps wider than 1 mm require a precisely fitted shim, usually applied by hand. The Airbus assembly team has reported stocking tens of thousands of different shims for A350 wingset assembly alone.

    • Can of 3M™ Scotch-Weld™ Advanced Liquid Shim EC-7272 B/A

      Airbus and 3M collaborate on liquid shim

      Airbus and 3M have combined their respective expertise in aircraft production and materials science to address these challenges. 3M™ Scotch-Weld™ Advanced Liquid Shim EC-7272 B/A is designed to fill gaps of up to 2.5 mm in composite structures with no solid shims or gap measuring required, helping substantially decrease cycle time and design cost.

      Scotch-Weld EC-7272 B/A is a two-part epoxy system that combines fast curing at room temperature with excellent toughness and high compressive strength over a wide temperature range. Its rheology enables fast, precise injection and high application versatility, helping increase production efficiency in the shimming process.

      The Airbus A350 wing assembly team has used liquid shim solutions from 3M to notable success. With Scotch-Weld EC-7272 B/A, the team was able to significantly reduce costs and achieve process and cycle time improvements including:

      • Minimal gap measuring
      • Reduced need to manufacture, deliver, store and bond solid shims
      • Fast application due to direct injection of liquid shim
      • Fast cure times (4 hours from application to drilling)

    New liquid shim for large areas

    3M™ Scotch-Weld™ Advanced Liquid Shim Adhesive EC-7200 B/A, launched in 2022, is designed for large area applications. Whereas Scotch-Weld EC-7272 B/A is typically injected, Scotch-Weld EC-7200 B/A is applied by a method known as “butter and paste,” in which the paste is spread onto the parts before the joint between the parts is closed. This plus its long work life and low sag properties make it ideal for large areas in primary and secondary aircraft structures.

    Authorization to use

    Ensure products meet all applicable specifications, standards, and maintenance manual requirements for the platform being worked on and validate all aircraft approvals against current technical documentation.