Refrigerator liner blister single-sided or double-sided heating

How to heat the plate of refrigerator liner suction molding machine?
The common heating methods of thick sheet blister are divided into single-sided heating and double-sided heating. When the thickness of plate and sheet is less than 2mm, single-sided heating is often used, and the heater should be placed under the sheet.
If it is larger than 2mm, it shall be heated on both sides at the same time. When single-sided heating is used,; When double-sided heating is adopted, the temperature of the lower heater shall be lower than that of the upper heater, and shall be 0.5~0.8 of the upper heating power.
The heating distance is usually 80~120mm.