Aerospace Shims

Shims look simple, but they solve one of the hardest problems in airframe assembly: no two aircraft come together with identical gaps. When a fastener pulls two structural members across an unfilled gap, it locks pre-load stress into the joint — a fatigue problem in metal structure and a delamination risk in composite structure. The shim fills that gap so the joint clamps flat. That is why modern Boeing and Airbus assembly processes are so disciplined about gap measurement and shimming, and why the Instaparts catalog carries roughly 20,000 shim line items among its 266,000+ parts.

Laminated (peelable) shims are the workhorse of the category: foil layers, usually 0.002 in or 0.003 in thick, bonded into a blank that can be drilled and trimmed like solid stock, then peeled to the measured thickness at installation. Edge-bonded constructions hold the pack together at the periphery so laminations strip cleanly. Solid shims — machined or stamped from certified aluminum, stainless, or brass sheet — serve fixed-thickness callouts and higher bearing loads. On top of these generic constructions sit thousands of drawing-controlled OEM part numbers: tapered wing-join shims, contoured splice shims, and fitting-specific parts that must be quoted by exact Boeing or Airbus part number.

Because a shim becomes permanent structure the moment the joint is torqued, the pedigree of the raw stock matters as much as the geometry. Instaparts, a division of RFQ2Go, Inc. in Toronto, Canada, operates an AS9120 Rev B certified quality management system: we source only from approved suppliers, maintain lot traceability of shim stock from receipt through delivery, apply counterfeit-prevention controls aligned with AS6081, and issue certificates of conformance with every shipment.

Shims are usually ordered alongside the fasteners that clamp them. Browse our aerospace bolts and aerospace rivets pages for the rest of the joint, or send your full bill of materials through our quote page for a fast, consolidated response.