What type of adhesive is mandated for high strength aircraft plywood?

Boiling water proof (BWP) synthetic resin adhesive conforming to IS 848.

What is the acceptable moisture content for this type of plywood?

The moisture content must be maintained between 8% and 14% at the time of testing and dispatch.

Can any hardwood species be used for manufacturing?

No, only specific high-strength species explicitly approved and listed in Table 1 of the standard (such as Rosewood, Teak, or Walnut) may be used.

IS 4859

: 1968

high strength aircraft plywood

CurrentSpecializedSpecificationMaterials Science · Wood and Other Lignocellulosic Products

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This standard specifies the requirements, grading, and testing methods for high strength plywood used extensively in the construction of aircraft and gliders. It mandates the use of specific high-strength timber species and boiling water-proof synthetic resin adhesives to ensure reliable performance under extreme flight and environmental conditions.

high strength aircraft plywood

Quick Reference Values

moisture content8 to 14 percent

adhesive gradeBWP (Boiling Water Proof) type

thickness tolerance upto 3mm± 5 percent

test specimen conditioning temp27 ± 2 °C

test specimen relative humidity65 ± 5 percent

Practical Notes

Strict quality control is mandatory; defects like knots, splits, and significant cross-grain are generally unacceptable in aircraft grade plywood.

Ensure the adhesive used strictly complies with IS 848 BWP grade, as aircraft plywood is subjected to severe environmental stresses.

Veneer thickness and grain orientation must be carefully monitored during manufacturing to meet the stringent tensile strength requirements.