1. Generate bubbles
Reason: Appropriate pressure can fully adhere the plastic during the heat sealing process, expelling the air between the plastic layers. If the pressure is not enough, air will remain between the plastics. Under the action of a high-frequency electric field, plastic begins to melt, but due to the inability to effectively expel air, these residual air will form bubbles.
For example, in heat sealed vacuum packaging boxes, if the pressure is too low, obvious bubbles will appear at the heat sealed area, affecting the sealing effect and appearance quality of the packaging.
2. The heat seal is not firm enough
Reason: Low heat sealing pressure can lead to insufficient contact between plastic materials. High frequency plastic heat sealer polarizes plastic molecules and generates heat through a high-frequency electric field, causing the plastic to melt and fuse together. When the pressure is insufficient, the degree of fusion between plastic molecules is not sufficient, only forming a thin layer of melting on the surface, and the plastic inside is not fully fused.
For example, for some plastic heat sealed products that require a certain weight or tension, if the heat sealing pressure is low, it is easy for the heat sealing part to crack during use, which reduces the quality and service life of the product.
3. Uneven heat sealing
Reason: Insufficient pressure can cause uneven contact between the plastic and the heat sealing mold (electrode plate). During the heat sealing process, pressure differences in different parts of the mold can lead to varying degrees of plastic melting. Areas with slightly higher pressure near the mold may melt better, while areas with lower pressure may only slightly melt on the surface, or even not melt at all.
For example, when heat sealing plastic products with complex patterns or multi-layer structures, such as car ventilation airbags, low heat sealing pressure can cause uneven heat sealing quality between different plastic layers, leading to air leakage and affecting the overall quality of the product.
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