1. Raw material quality control
To ensure the smoothness of the surface quality of PS Blister Tray, we first need to start with the raw materials. The quality of PS sheets has a significant impact on the surface flatness of the pallet. PS sheets of high quality and uniform thickness should be selected, because uneven sheet thickness will cause uneven surfaces during the blister process. When purchasing, the thickness tolerance of the sheet must be strictly inspected. Generally, the tolerance range needs to be controlled within a very small range, such as ±0.05mm, and the sheet must be free of impurities, bubbles and other defects. These impurities and bubbles may cause uneven local stress during blister molding, causing unevenness on the surface of the pallet. Moreover, the quality of PS sheets produced by different manufacturers may vary, so you need to choose a supplier with a good reputation and quality assurance.
2. Optimization of blister process parameters
Blister process parameters are the key to ensuring the surface smoothness of the pallet. Temperature is one of the important parameters. Appropriate heating temperature can soften the PS sheet evenly. If the temperature is too high, the sheet may soften too much or even decompose, causing wrinkles or unevenness on the surface; if the temperature is too low, the sheet will not soften enough and cannot fully fit the mold, affecting the flatness. Generally speaking, the heating temperature of PS sheets needs to be adjusted within an appropriate range according to the thickness and performance of the sheet. For example, for PS sheets with common thicknesses, the heating temperature can be controlled between 120-150°C.
The degree of vacuum is also crucial. Sufficient and stable vacuum can ensure that the sheet is quickly and tightly adsorbed and formed in the mold. If the vacuum is too low, air will easily remain between the sheet and the mold, forming bubbles or local bulging, destroying the surface flatness. During the blister process, maintaining a stable vacuum degree can be achieved by regularly inspecting and maintaining the vacuum system to ensure that the fluctuation range of the vacuum degree is extremely small.
3. Mold quality and design
High-quality and reasonably designed molds are the guarantee for producing flat PS Blister Tray. The roughness of the mold surface should be low, generally reaching Ra0.8-Ra1.6μm, which can reduce the friction between the sheet and the mold surface, enable the sheet to better fit the mold, and avoid surface scratches caused by friction. Or uneven. The exhaust design of the mold is also critical. A good distribution of exhaust holes can allow air to be discharged smoothly and prevent problems such as bubbles caused by residual air during the blister process. In addition, the precision of the mold must be high, and the dimensional and shape tolerances must be strictly controlled to ensure the flatness and smoothness of the mold cavity, thereby ensuring the surface quality of the pallet after molding.
4. Production environment control and post-processing
The production environment also has an impact on the surface flatness of PS Blister Tray. Changes in ambient temperature and humidity may affect the physical properties of the PS sheet. For example, high humidity will cause the sheet to absorb moisture, affecting its softening and molding effects. Therefore, the production workshop should maintain relatively stable temperature and humidity. The temperature can be controlled at 20-25°C and the humidity at 40%-60%.
After the pallet is blister formed, appropriate post-processing can be performed to improve the flatness. For example, lightly flatten the pallet and use a flat pressing plate to decorate the surface of the pallet under a certain pressure, but be careful not to use too much pressure to avoid damaging the pallet. At the same time, the pallets are visually inspected to detect and deal with surface unevenness in a timely manner, such as repairing local bulges or depressions or removing unqualified products.