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2026
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Wrong temperature, and all your efforts are for nothing! Here are several typical cupping profiles that suffer when the wrong temperature is used.
Author:
In the world of thermoforming, temperature is both the magic wand that turns the ordinary into the extraordinary and the spark that can reduce everything to ashes.
Stepping into a bustling cup‑manufacturing workshop, everything appears orderly: machines rumble, sheets of material shuttle back and forth, and cups emerge in neat succession. Yet an experienced master craftsman can tell at a glance whether the kiln temperature is just right. Temperature—seemingly a mundane parameter—actually marks the critical threshold that transforms plastic from a state of “utter chaos” into a “fine piece of craftsmanship.”
Use the wrong temperature, and even with the finest raw materials and the most precise molds, what you end up producing is nothing more than a “typical cup product” destined for obsolescence. Today, let’s take a look at several examples born from uncontrolled temperatures. “Negative example” ”。
Case One: PET “Cataract” Cup
Phenomenon The PET beverage cup, which should have been crystal clear, is now covered in a layer of white haze, as if suffering from “cataracts,” with no trace of transparency.
Temperature error ：
1. The sheet heating temperature is too low. : PET has not reached its fully amorphous, highly elastic state, and the polymer chains have not fully extended. During stretch‑forming, countless microscopic stress cracks form, causing light to undergo diffuse reflection at these cracks and resulting in a sharp increase in haze.
2. Mold temperature is too low : The cold mold causes the melt at the contact surface to cool rapidly and undergo excessive crystallization, forming a highly crystalline, milky-white layer.
Key Lessons : To produce highly transparent PET products, it is necessary to provide Sufficient and uniform heat , enabling it to undergo gentle stretching and slow cooling within the optimal temperature window—typically between the material’s glass transition temperature and its crystallization melting point.
Case Study 2: The PP “Soft-Boiled Shrimp” Cup
Phenomenon : Thick-walled milk tea cups or food containers feel soft and pliable; when filled with hot water, the cup body deforms severely, collapses, and even the lid becomes difficult to seal.
Temperature error ：
1. Insufficient overall heating of the sheet material : The PP was not fully plasticized, and the internal crystalline regions were not adequately melted, resulting in excessive material “memory.” Upon secondary heating—such as when hot water is poured—the internal stresses are relieved, causing the material to attempt to return to its original shape and leading to severe shrinkage and deformation.
2. Local temperature unevenness : The heating tubes in the heating plate have failed, resulting in localized “undercooked” areas in the sheet material. After forming, these regions exhibit extremely low strength, becoming structural weak points.
Key Lessons : The heat resistance and rigidity of PP depend on the structure formed during the molding process. Stable, uniform crystalline structure This requires precise and stable temperature control throughout the entire process, from the sheet material to the mold.
Case Study 3: PS “Crispy Fried Chicken” Cup
Phenomenon : Cold beverage cups or yogurt cups have an unusually brittle texture; they shatter with a gentle squeeze, or develop radial cracks starting from the cup’s rim.
Temperature error ：
1. Molding temperature too high PS is a thermosensitive material; excessive heating can cause severe degradation (depolymerization) of the molecular chains, rendering the material extremely brittle and losing its toughness.
2. Cooling too rapidly After forming at excessively high temperatures, if the material is cooled too rapidly, significant residual stresses can accumulate within the cup. These stresses may be released under even slight external forces or environmental changes, leading to brittle fracture.
Key Lessons : When machining brittle materials such as PS, it is essential to Strictly control the temperature upper limit. and employs a gentle, uniform cooling process to eliminate residual stresses.
Conclusion: Precise temperature control is the “soul” of the equipment.
Each “typical cupping” is an expensive lesson. Together, they reveal a fundamental truth: in the field of plastic thermoforming, Temperature is not an isolated metric; rather, it is a core system tightly coupled with material properties, product design, and manufacturing efficiency.
A professional cup-making machine is valued not merely for its speed and pressure, but rather for its ability to provide a tailored solution for products made from diverse materials and featuring varied structures. Precise, stable, uniform, and repeatable temperature solutions . This includes:
1. Multi-zone independent temperature control It allows fine-tuned adjustment of different heating zones, accommodating complex sheet materials or localized variations in thickness.
2. High-precision sensors and closed-loop control Real-time feedback and instantaneous adjustment ensure that the set temperature matches the actual temperature.
3. Stable thermal equilibrium system : Ensure that, during continuous production, the temperature does not drift due to environmental conditions or load variations.
When the temperature is just right, a material’s inherent potential is fully unleashed; when it’s off, all process efforts are halved in effectiveness. Choosing equipment that masters “temperature control” is the first—and most critical—safeguard for your product quality.
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