Common packing jobs for 6-sided liners
Heavy component isolation
Dense metal parts or motors can easily pierce a standard outer box during transit. The liner acts as an internal bumper, absorbing lateral shocks while the base flaps prevent the product from punching through the floor.
Fragile product cushioning
For electronics or glass, the inward-folding top and bottom flaps create a double-wall air gap at the most vulnerable impact points, distancing the product from the outer carton.
Pallet stacking reinforcement
When standard shipping boxes buckle under heavy vertical weight, dropping a liner inside adds immediate column strength along the vertical flutes, often preventing the need to upgrade the entire master carton run.
Multi-layer separation
For shipments containing multiple heavy items, the inward-folding flaps can act as a false bottom or divider, keeping dense components separated from lighter accessories packed above them.
Fulfillment and distribution contexts
Industrial kitting and parts distribution
Assembly lines packing heavy hardware kits use the liner to keep dense parts contained and separated from the outer shipping shell, ensuring the master carton arrives intact.
Appliance and electronics shipping
Distributors use the top and bottom flaps to create a protective ceiling and floor over sensitive screens or control panels, reducing drop-shock damage.
E-commerce fulfillment for dense goods
Retailers shipping heavy liquids, canned goods, or dense tools use this insert to prevent base blowouts and side-wall piercing during rough courier handling.
When to consider a different internal liner
When top and bottom cushioning is unnecessary
If the product only needs lateral side-wall protection or vertical stacking support, a simple 4-panel sleeve (FEFCO 0904) removes the top and bottom flaps. This eliminates the need for slotted manufacturing and speeds up the packing process.
When the liner needs to ship independently
If the internal component might occasionally be used as a standalone shipping box, a Regular Slotted Container (FEFCO 0200) adds a glued manufacturer's joint, allowing it to hold its shape without a master carton.
Clearance, board, and packing decisions
Master carton clearance and fold allowances
Because the liner sits inside another box, the board thickness directly reduces the usable internal volume. Heavy double-wall board provides excellent protection but requires precise fold allowances to ensure the liner's corners do not bind when inserted.
Managing packing labor and spring-back
This liner has unjoined ends and relies entirely on friction fit. Operators must fold the panels, hold the tube closed against the board's natural spring-back, and plunge it into the master carton. This manual step should be factored into high-volume fulfillment planning.
Flap folding sequence
Depending on the product, the bottom flaps can be folded inward before the product is loaded to create a base cushion, while the top flaps are folded over the product just before sealing the master carton.
Board grade selection
Choosing between single-wall and double-wall corrugated board changes the shock absorption capacity. Thicker board offers better puncture resistance but demands wider slotting and reduces the available space for the actual product.
Practical template adjustments
Flap length modifications
The length of the top and bottom flaps can be adjusted. They can be sized to meet exactly in the center for a flat floor, or made shorter if they only need to act as perimeter bumpers.
Flute direction alignment
To act as a load-bearing column, the corrugated flutes must run vertically through the main panels. This alignment transfers top-load weight directly to the box floor.
Slot depth adjustments
The vertical slots separating the top and bottom flaps can be deepened or widened to accommodate thicker board grades, ensuring the flaps fold inward 90 degrees without tearing the adjacent corners.
Board and packing details
Friction fit and outer box pairing
The liner is designed to sit flush against the inner walls of the master carton. A loose fit reduces its ability to brace the outer box against diagonal skewing.
