Design and Mold Development

The shape of a tin box doesn't come from guesswork — it comes from a mold. And mold development is where most of the real engineering work happens.

For standard shapes (round, rectangular, square, cylindrical, oval), we work from our existing library of 2,000+ molds. A client picks a size, we already have the tooling, and sampling is fast.

For custom shapes — an irregular silhouette, a heart-shaped gift box, a ball-shaped tin — a new mold has to be designed and cut. That involves 3D modeling, tolerance calculations, and test pressings before anything gets approved for production. The mold determines the final dimensions with high precision. A lid that's off by even 0.2mm will feel loose or won't close properly.

Printing Before Forming

Here's the part that surprises most people: the design gets printed on the flat tinplate sheet before the metal is shaped into a box.

This is called pre-printing, and it's the standard approach in tinplate manufacturing. The flat sheet goes through offset printing (or UV printing, or screen printing), where color layers are applied and cured. Surface finishes like matte varnish, gloss coating, gold stamping, or embossing are also applied at this stage.

Why print flat instead of on the finished box? Because flat surfaces print with far more precision and consistency than curved or formed ones — sharper registration, cleaner gradients, better color accuracy. Once the tin is formed, reprinting any part of it is essentially impossible.

Cutting and Blanking

After printing, the large tinplate sheets are cut into precise blanks — flat pieces sized and shaped for each specific component of the tin. A basic lidded box might require two blanks: one for the body, one for the lid. A tin with a hinge, a window panel, or a sliding mechanism will have more components, each cut separately.

Cutting is done by stamping presses with precision dies. The edges are clean, the dimensions are exact, and waste is minimized by nesting the blank shapes efficiently across the sheet.

Forming — Where Flat Becomes Three-Dimensional

The flat blanks go into stamping and drawing machines that use dies and punches to press the metal into shape. Depending on the box design:

• Round and cylindrical tins — formed by deep drawing, the metal stretched and pulled down into a circular die
• Rectangular and square tins — formed by bending and flanging, with corners seamed or welded
• Sliding tin boxes — a shallow tray and a closely fitted sleeve, both formed separately
• Hinged tin boxes — additional operations to form and attach the hinge mechanism

Multi-stage forming is common for deeper boxes — the metal is gradually drawn down over several press operations rather than all at once.

Assembly

Once the individual components are formed, they get assembled. For a simple lid-and-body tin, this might just mean sizing the two parts so the lid fits correctly. For more complex products:

• Child-resistant tins — the push-and-turn or squeeze-and-pull mechanism fitted and tested
• Tin boxes with windows — the PVC or PET film panel inserted and secured
• Tins with handles and locks — hardware attached and function-tested
• Jewelry and watch tins — foam padding, velvet lining, or vacuum-formed trays fitted inside

At Longteng we run 4 dedicated assembly lines alongside 11 automatic production lines, which allows us to handle both high-volume simple tins and more complex multi-component packaging without lead times ballooning.

Quality Control

A tin box that looks good in a sample photo and holds up through bulk production and international shipping are two very different things. QC runs through every stage — material inspection, print color checking, dimension verification after forming, and functional testing on assembled units.

For food-grade tins (cookie tins, tea canisters, coffee tins), the internal coatings also get checked for compliance. Tins bound for the EU or North America often need specific certifications, and that documentation starts at the material sourcing stage, not after production.