The Machine Sets the Limits; the Mold Sets the Product

Buyers compare machines by tonnage, stations and speed. But between two identical machines, the one with the better mold produces the better part. Wall distribution, rim flatness, denesting force and trimming quality are all decided inside the tool.

Shantou Longsheng Industry Co., Ltd. manufactures precision molds in-house in Shantou City, Guangdong Province — one reason its cup machines and thermoforming lines are specified as a matched system.

The Decisions Inside a Thermoforming Mold

Draft angle and plug geometry. A cup needs enough draft to release without force, but not so much that the base thins out. The plug-assist shape controls how material is stretched into the cavity — the single biggest lever on wall distribution.

Venting. Trapped air between plug and sheet causes local thin spots and slow forming. Micro-vents in the right places let air escape in milliseconds.

Cooling channels. Cycle time is a cooling problem. Balanced channels in both mold halves keep every cavity at the same temperature, which keeps shrinkage — and therefore rim flatness — identical across the tool.

Cavity count. More cavities raise output but tighten every tolerance, because one badly vented or poorly cooled cavity becomes the bottleneck for the whole tool.

Rim and trim geometry. For sealed cups, the rim bead must land within tolerance in every cavity; the trim die must cut clean through without burrs.

Why In-House Mold Making Matters

When the machine builder and the mold maker are the same company, three things improve. First, the forming window is designed with knowledge of the actual machine's heating and indexing behaviour. Second, changes during trials are fast, because machining happens in the same plant. Third, spare tools and replacement cavities are reproduced identically years later.

Longsheng's mold capability supports its full range: cup making machines in three drive platforms (FS-8556 full servo, HSS-8556 hydraulic servo, HAI-8556 hydraulic), multi-station thermoforming machines and vacuum forming machines.

A Practical Example

A 24-cavity PP drinking cup tool illustrates the chain: plug shape sets base thickness, venting sets cycle time, cooling balance sets rim flatness, and the trim die sets denesting. Change any one of them in isolation and another moves — which is why the tool is designed and validated as a system.

Company Facts

Founded in 1998, Longsheng operates a 30,000 square metre facility, holds 25 authorised patents (1 invention, 24 utility model) and is a high-tech enterprise under the registered "Longsheng" trademark.

For mold design consultation, visit the official website: https://www.stlongsheng.com