Is the wall always continuous fibre?

A: No. Only continuous filament layups qualify; chopped-strand mouldings behave an order of magnitude apart.

Why does the case need metal inserts?

A: Bolt and hinge loads concentrate. An insert spreads the load over a wider area.

Can a damaged case be repaired?

A: Small delamination can be ground back, patched and cured. Penetration or wide delamination means replacement.

Does lighter mean weaker?

A: Not against impact, where layup and energy absorption decide. It is weaker against point load and puncture.

What matters on a salt-spray site?

A: An intact gel coat. Check corners and cut edges twice a year. ---

Container, Ammunition, Fiber: The Lightweight Packaging Route

Quick answer: A fiber container, ammunition, fiber in the trade sense is a case whose load-bearing wall is continuous fibre laid in resin under a protective coat. Strength comes from the layup, not from extra thickness. It wins on weight, salt spray and non-magnetic behaviour; it loses on point load, heat and repairability. The test that separates it from a plastic case is whether the wall holds continuous fibre.

What a fiber container, ammunition, fiber is: four wall layers
Fibre and resin: which layer carries the strength
Moulding routes: press, infusion and rotomoulding
The weight ledger: where each kilogram goes
Protection limits: what it does and does not do
FAQ

1. What a fiber container, ammunition, fiber is: four wall layers

Cut the wall open and it is four layers, not one material. The liner faces the interior and handles sealing. The continuous fibre layer follows the load paths and sets how much bending and impact the case survives. The resin bonds the fibres into one body and passes shear between them.

That is where it parts from an injection-moulded case. Moulding is isotropic. A layup is anisotropic: load travels along the fibres and the stacking angle decides which direction ends up strong. One question separates the two at quotation stage, continuous filament or chopped strand.

Close-up of the lid label recess with white SIKARLAN lettering on a matte black face inside a raised border

Layer	Typical material	What it does
Load-bearing	Continuous glass, aramid, carbon	Bending and impact
Matrix	Epoxy, vinyl ester, polyurethane	Bonds fibre, passes shear
Liner	Thermoplastic film, gel coat	Sealing and cleaning
Outer coat	Abrasion-resistant gel coat	UV and grit

2. Fibre and resin: which layer carries the strength

Three numbers pick the fibre: density, tensile modulus, elongation. Glass is cheap with a middling modulus. Aramid stretches further and resists cutting. Carbon is stiffest but costs more and corrodes against aluminium.

The matrix is undervalued. Fibres carry tension and little compression; the resin restrains them against micro-buckling. Too little resin leaves no shear path between filaments, so an impact delaminates the wall. Too much drops the fibre fraction, usually held between fifty and sixty-five percent by volume. Stacking angle then decides where that strength points.

A black braided cord laid flat, a moulded plastic fitting at each end, slim left and disc-shaped right

3. Moulding routes: press, infusion and rotomoulding

Prepreg pressing cures impregnated cloth in a heated mould: clean faces, stable dimensions, expensive tooling, best for a settled model. Vacuum infusion wets dry cloth under vacuum: mid-priced tooling, suited to large parts and shorter runs.

Rotomoulding has no fibre in it. Powder fuses inside a rotating mould into a hollow shell — even wall, low cost, free shapes, but stiffness bought with thickness. Both are black hard shells; the difference is inside the wall.

The same case from the other side: both latches on the upper edge, one large rectangular recess in the flank

4. The weight ledger: where each kilogram goes

On the same interior, a fibre case runs about thirty percent lighter than cold-rolled steel and ten to twenty lighter than aluminium. Structural efficiency explains it: fibre sits only where load runs, instead of margin in every direction.

There is a floor. Latches, hinges, valves and gaskets stay metal and rubber, and they hold twenty to thirty percent of finished weight. Shrink the case and those parts do not shrink with it.

Part	Material	Share of weight
Shell	Layup in matrix	65 to 75 percent
Latches, hinges	Plastic, stainless	10 to 15 percent
Gasket	Silicone, EPDM	5 to 8 percent

5. Protection limits: what it does and does not do

It does three things well: drop and side impact, salt spray, radio transparency. Energy spreads through the layup and the radiused corners stop it concentrating on one point; the resin takes no part in galvanic corrosion; glass and aramid neither distort a field nor block RF.

Sharp feet press dents into the wall until it delaminates. Epoxy service stays under 120 °C. UV chalks the coat. A penetrating break takes a bonded patch, not a hammer.

Closed case marked 222 by 128 by 50 mm; open view marking a 200 by 98 mm interior and 26 mm lower depth

Conclusion

The position is clear: where weight, corrosion or RF transparency drive the choice, the composite wins; where point load, field welding or sustained heat drive it, metal still does. Read the load case first, then decide whether the wall needs fibre at all.

This article covers container-side specifications and design implications only, not the handling, loading or use of the contents.