What the Process Factors Affect Wall Thickness Uniformity in Thermoforming Products?
What the Process Factors Affect Wall Thickness Uniformity in Thermoforming Products?
What is Thermoforming
It is a plastics processing method where thermoplastic sheets are formed into various products.The sheet is clamped onto a frame, heated until pliable, then forced against the mold contour using vacuum/pressure, it is made to adhere to the profile of the mould in order to obtain a shape similar to that of the profile. After cooling and forming, it is trimmed into products. It offers high production efficiency, requires relatively lowthermoforming machine investment, and can produce large-format items.
What Are the Products of Thermoforming?
Because plastic thermoforming machine can form into any shape, it is used for a wide range of purposes, including everyday items, toys and pharmaceuticals. In particular, it is often used for the following purposes.
1. Pharmaceutical Packaging
Thermoforming packaging seals medications, protecting them from air and moisture exposure. They are also usually individually wrapped to provide a precise dose of medication.
2. Food Packaging
Thermoforming packaging safeguards sensitive foods like produce and meats during transport while maintaining freshness.sensitive foods such as fruits, vegetables and meat during storage and transport. In addition, individually wrapped food can keep fresh and prevent spoilage.
3. Cosmetic Packaging
Generally, small cosmetics, especially lipsticks and eyeshadow discs. This is because it not only protects the product from external influences, but also allows consumers to view the product without opening it.
4. Packaging of Electronic Components
small electronic components, especially microchips and LEDs, the product is protected from external influences such as static electricity and the packaging is transparent so that the consumer can see the product.
Thermoforming Products Wall Thickness Uniformity of Process Factors
Heating: Suitable heating conditions should allow the entire sheet to warm up uniformly in all parts of the heating process.
Forming: Wall thickness variation primarily stems from non-uniform material distribution during stretching., and the other is the magnitude of the stretching speed, that is, the gas flow rate of pumping, inflating, or the speed of movement of the moulds, clamping frames, and pre-stretching plungers. Generally speaking, a high stretching speed on the moulding itself and shorten the cycle time are more favourable, but Excessive stretching speed may cause material starvation, resulting in overly thin walls at convex/concave features., convex parts of the phenomenon of wall thickness is too thin: and stretch too slow and because of the sheet overcooling caused by the deformation of the ability to reduce the product cracks. The size of the stretching speed and the temperature of the sheet moulding has a close relationship, the temperature is low, the sheet deformation ability is small, should be slow stretching. If you want to use high stretching speed, you must increase the temperature when stretching.
Cooling: Parts should cool below their heat distortion temperature prior to ejection to prevent warpage, otherwise the cooling is insufficient, the deformation will be deformed after demoulding. Cooling rate is related to the thermal conductivity of the plastic and the wall thickness of the moulded product. Appropriate cooling rate, should not cause too large a temperature gradient in the product to produce large internal stress, Excessive cooling rates may induce micro-cracks in high-stress areas due to thermal stress concentration.