Freezer Service Is a Different Mechanical Test

Packaging that performs at room temperature can fail in a display freezer at −18°C. Materials stiffen and lose impact strength; a rim that sealed at +20°C can crack when flexed frozen. Frozen-food packaging is therefore designed around low-temperature toughness, not just cost.

Shantou Longsheng Industry Co., Ltd. supplies cup making machines, multi-station thermoforming machines and precision molds for this segment from its plant in Shantou City, Guangdong Province.

Typical Frozen and Chilled Formats

• Ice cream cups and tubs, from single-serve 60ml to family packs
• Frozen dessert and mousse cups with flat sealing rims
• Frozen meal trays, single and multi-compartment
• Ice lolly and popsicle holders
• Frozen berry and vegetable trays
• Lids: snap-on, sealing-film and hinged formats

Material Behaviour at Low Temperature

PP becomes brittle as temperature drops, so frozen PP parts need tougher grades, thicker walls or living hinges redesigned for cold flex. It remains the choice where microwave reheating of the same pack is required — a common requirement for ready meals.

HIPS keeps good impact behaviour in the cold and is a classic frozen tray material where clarity is not critical.

PET retains stiffness and clarity but also embrittles at deep-freeze temperatures; grades are selected accordingly.

PLA is limited for frozen service and is used mainly for chilled, short-shelf-life products.

Longsheng machines process PP, PS, HIPS, PVC, PET, PLA, PE and biodegradable sheet, so material changes do not force equipment changes.

Design Details That Matter in the Cold

Snap-fit lids need a generous interference at room temperature but must not stress-crack when closed frozen. Compartment trays need corners rounded enough to resist impact cracking. Sealing rims must stay flat after the pack leaves the freezer and condenses. Each is a tooling decision: radius, wall thickness and rim profile are set in the mold.

Stacking also changes — nested frozen cups are separated by machines and by gloved hands, so denesting force must stay low even when the material is stiff.

Company Background

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

For frozen packaging projects, visit the official website: https://www.stlongsheng.com