The principle of thick sheet blister processing is basically the same as the conventional blister process. The plastic sheet is cut into a certain size and heated and softened. With the help of the air pressure difference or mechanical pressure on both sides of the sheet, it is deformed and covered on a specific mold. The contour surface is cooled and shaped, and trimmed to obtain the desired product.
The commonly used raw materials for thick plastic blister mainly include HDPE, ABS, ABS+TPU, etc. The following briefly introduces the basic characteristics of these three materials.
(1) HDPE (high-density polyethylene) material: it has good heat resistance, cold resistance, chemical stability, high rigidity, toughness and excellent environmental stress cracking resistance. Main uses: 200-liter buckets, fuel tanks, pallets, large parts, yachts, blister tray top covers, special packaging for most auto parts, etc
heavy gauge thermoforming manufacturers said that there are two main ways of forming molds, concave mold vacuum forming and convex mold vacuum forming.
The sheet is fixed around and sealed above the mold cavity, the sheet is heated to soften, and then the air in the cavity is drawn out to form a vacuum, so that the sheet is pressed against the mold cavity under high pressure to form. After cooling and shaping, compressed air is passed through the suction hole below to make a blister box. Concave mold vacuum forming is suitable for blister boxes with a small depth. If the product is too high and the depth is too large, the sheet will easily form a phenomenon that the bottom is too thin due to excessive stretching.
The sheet is clamped above the mold cavity and heated to soften. The material is covered on the punch like a tent, that is, it is cooled and loses its ability to thin. Convex mold vacuum forming is mostly used for products that have higher hardness requirements on the bottom of the blister box, and the inner and outer dimensions after forming have higher dimensional accuracy