Injection Molding Cell Creates Plastic Beverage and Food Can Covers

Rick Lingle | Sep 28, 2022

Together with three project partners, Austrian company Elmet developed two innovative injection-molding production cell that manufacture four different covers for beverage and food cans, which have been dubbed as Smartcaps.

Smartcap is a collaborative project that also involved Sumitomo (SHI) Demag, Shin-Etsu, and Mettler Toledo.

With Elmet‘s Smartshot E and Smartmix Top 7000 Pro systems, two of the company's technological flagships are used in the production cell.

Lids for food & beverage cans are manufactured by the Elmet injection molding system with an all-electric Smartshot E valve-gate cold-runner system.

The technological high-end counterpart in material provision is the Elmet Smartmix Top 7000 Pro dosing system, which delivers precise and reliable dosing of material to the Elmet injection mold. A Sumitomo linear handling device removes the parts from the mold and transfers them to the weighing cell made by Mettler Toledo where every part is weighed. The result is stored in a database and displayed graphically to demonstrate the process accuracy of the system. After weighing, the silicone parts are marked by laser to ensure highest possible traceability. After lasering, the parts are placed on a conveyor belt.

PlasticsToday learned from Michael Schaffer, Elmet's business unit manager tooling & turnkey, that the company built a 4-cavity mold specifically for the K Show. It will be used to make Smartcap lids in the Sumitomo booth as a souvenir for visitors, he adds.

The heart of the innovation is the interaction between the high-tech contributions from the four partner companies. The combination of high-precision dosing (Elmet Smartmix), the all-electric injection-molding machine (Sumitomo IntElect), and the electric valve-gate cold runner (Elmet Smartshot E) enables a new level of accuracy in the reproduction of part weights.

The special four-cavity injection mold from Elmet injects four different can lids made of liquid silicone (LSR) from partner company Shin-Etsu. The silicone lids produced serve as coverings for customary beverage cans such as those for soft drinks, energy drinks, and various alcoholic beverages. A separate cavity also produces covers for customary food cans made of sheet steel.

The dosing system design was focused on reducing the unit's footprint to 1,150 mm/55.3 inches by 790 mm/31 inches. This makes the system the smallest liquid-silicone dosing system for 200-Liter container units on the market.

Compared to its predecessor, the Smartmix TOP 5000 P, the Smart TOP 7000 Pro features a completely new pump system, which now only contains approximately one third of the liquid silicone in the system, making it much easier to clean. This is particularly important for use in the medical and pharmaceutical fields where the pump unit is dismantled and cleaned each time the material changes to prevent mixing of different types of liquid silicone.

Apart from the new pump unit, an optimized follower plate geometry also helps reduce the amount of residual material.

The new system boasts a material utilization level of up to 99.6%. Drums are changed automatically to increase ease of use and keep the amount of training to a minimum. Use of special seals made of FDA-compliant materials allows the Smartmix Top 7000 Pro to be used for medical applications.

The system can be seen for the first time at the Sumitomo booth at K 2022 in Düsseldorf, Germany, Hall 15, Booth D22.

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