Total barrier,
no heatCold forming shapes aluminium laminate with a plug at room temperature — an alu-alu blister that blocks light, moisture and oxygen completely. For pharmaceuticals and the most sensitive products.

Cold form foil (CFF) is a three-layer laminate built around soft-tempered aluminium: an outer nylon (OPA) layer that carries the forming stretch, the aluminium core that provides the barrier, and an inner PVC layer that heat-seals to the lidding. The aluminium is the point: unlike any polymer, it transmits essentially zero oxygen, water vapour or light. Formed into a cavity and closed with aluminium lidding, the pack is barrier-complete on all six sides — which is why alu-alu is the reference format for the most sensitive pharmaceuticals.

Metals don't thermoform — they yield. In cold forming, a precisely shaped plug presses the laminate into the die cavity at room temperature; the aluminium stretches past its elastic limit and keeps the shape permanently. No heating stage, no cooling stage, no thermal stress on the laminate. The constraint is geometry: aluminium tolerates far less stretch than a hot polymer, so cavities need gentle draw angles, generous radii and shallower proportions. Push the geometry too hard and the laminate develops pinholes — invisible breaches that defeat the whole barrier. Getting the plug profile and draw ratio right is the craft.

The failure mode unique to cold forming is the pinhole: a microscopic crack in the aluminium where the stretch was too aggressive — at a corner, a radius, a too-steep wall. Prevention is geometric (conservative draw ratios, polished plug surfaces, even blank holding) and verification is empirical: formed cavities are inspected and the forming process validated so the barrier the laminate promises is the barrier the pack delivers. This is a tooling-and-process discipline — and both live under our roof.

Cold form tooling looks deceptively simple — a plug and a die — but the details decide the barrier. The plug's profile controls how the stretch distributes across the cavity; its surface finish must be polished, because any roughness scores the nylon layer and seeds pinholes. The blank holder — the frame that grips the laminate around the cavity — sets how much material feeds into the draw versus how much stretches; too tight and the foil thins dangerously, too loose and it wrinkles. Die radii, plug speed and hold time complete the recipe. We design and cut this tooling in-house, which means a cavity geometry can be tuned against inspection results in days — the same rapid loop we run for thermoform tooling.

Alu-alu blisters close with aluminium lidding foil, welded on with a knurled seal — a grid pattern that concentrates the seal force into many small points for a strong, even joint. Standard lidding is push-through: firm enough to hold the dose, frangible enough to burst when pressed. Where regulation or risk demands it, child-resistant constructions come in: peel-push laminates that require two distinct motions, or paper-backed foils that resist a child's push. The lidding choice is a compliance decision as much as a technical one, and it's specified together with the pack.

Because aluminium stretches less than hot polymer, an alu-alu cavity needs more flat area around each pocket — the blister card grows, sometimes considerably, versus a thermoformed equivalent. The pack is also opaque: no product visible, so identification moves to print. The decision is rational: if stability testing shows the product survives its shelf life behind a high-barrier polymer film (PVdC, PCTFE), a thermoformed blister is smaller and cheaper. If it doesn't — or if the market demands the security of total barrier — alu-alu earns its footprint. We help you make that call on data, not habit.

Pharmaceutical blister packaging carries pharmacopoeial and GMP expectations: documented materials, validated forming and sealing processes, and batch traceability from laminate roll to finished box. Under the MedicoPax brand this is built into the flow — materials documented for medical use, seal and forming validation delivered as a package, clean-condition handling, and every box and bundle labelled and logged. The blister is a regulated component of the medicine; we treat it that way. See validation and traceability.

A clear blister lets the product identify itself; an alu-alu blister cannot — everything the patient and the supply chain need must be carried by print. Lidding foils are printed with product name, strength and batch information, and dose-by-dose marking — day labels, taper schedules — is printed cavity-aligned so it survives the die cut in register. Serialization requirements, where they apply to the secondary pack, put demands on batch discipline underneath: every forming and sealing batch must be traceable so the printed data and the physical product never drift apart. That chain — laminate lot, forming batch, lidding print, box label — is exactly what our traceability system records.

Two situations push a product from high-barrier polymer film into alu-alu. The first is climate: stability requirements for hot, humid markets — the ICH's tropical climate zones — are brutal on hygroscopic formulations, and moisture that a coated film admits over 24 months is moisture the aluminium simply never lets in. The second is shelf life itself: every extra year of dating multiplies the transmitted oxygen and water a polymer barrier must be tested against, while the aluminium barrier stays flat at zero. If your product is stable, sell it in a smaller, clearer pack. If it isn't — or your registration spans climate zones — alu-alu is the format that makes the stability file boring, which is exactly what a stability file should be.

Cold form foil is more delicate to handle than it looks finished. Before forming, the laminate is soft-tempered aluminium sandwiched between thin polymer films — a crease, a scuff or a hard nip roller can damage the barrier layer invisibly, seeding exactly the pinholes forming is trying to avoid. So the material is stored and fed with care: controlled tension, clean rollers, no sharp direction changes, and protection from mechanical marking across the whole path from roll to tool. The forming step then works within the metal's limited ductility rather than fighting it. This handling discipline is unglamorous but decisive — a large share of alu-alu barrier failures trace not to the forming geometry at all, but to damage the foil picked up on its way to the plug.