Professional manufacturer of thermoforming machines.
Language
Professional manufacturer of thermoforming machines.
In thermoforming machine, the thermoplastic sheet softens when heated and is stretched and adsorbed onto the mould, after which the formed material must be cooled rapidly below its glass transition temperature before demolding. The cooling system affects productivity, product quality and dimensions.
1. Air cooling
Principle: Air cooling is a relatively simple and economical way of cooling, mainly through natural convection or forced air cooling to take away the heat from the mould. The heat emitted from the surface of the mould is removed by a fan or air circulation device.
Methods:
Compressed Air Cooling: Compressed air is blown to the inside and/or outside of the moulded part through nozzles/air holes in the mould or moulding equipment. Large areas can be cooled quickly.
Exhaust fan/blower cooling: A fan or blower is set up outside the thermoforming machine to blow air over the entire moulded area or specific parts.
Advantages: Simple, low cost, no wetting of the product.
2. Water Cooling
Principle: Cooling channels are set up inside the mould so that the cooling water is circulated continuously to take away the heat.
Mode:
Water Mist Cooling: Precision nozzles mounted above the mold cavity distribute fine water droplets to spray cooling water mist or fine water flow to the outer surface of the moulded parts (usually the convex side of the mould).
Direct Contact Cooling (Conventional Mold Cooling): Inside the mould (usually concave mould) processing cooling waterway, through the circulating cooling water (often with a water chiller), through the heat conduction of the metal mould to indirectly cool the plastic surface in contact with the mould.
Spray cooling: the cooling water is atomised and sprayed onto the surface of the product, combining the rapid heat absorption and evaporative cooling effect of water, with high efficiency.
Advantages: fast cooling speed, improve production efficiency
3. Contact cooling (mainly rely on the mould)
Principle: Built-in cooling waterway, direct contact with the hot plastic, through heat conduction to take away the heat. Generally closely combined with water cooling (mould waterway) or air cooling (mould temperature control).
Advantage: Uniform cooling
4. Composite cooling
Principle: In practice, a combination of cooling methods is often used in order to achieve the best cooling effect and efficiency.
Type of plastic;
Thickness of the material after stretching;
Forming temperature;
Material of the vacuum forming mould;
Degree of contact between the moulds;
Cooling by air or other media, where the surface of the product does not contact the mould.
The cooling system of thermoforming machine is the key to ensure the smooth running of the thermoforming process. The cooling system not only affects the production efficiency, but also directly relates to the product quality. Each cooling method has its own advantages and disadvantages, the specific choice of which method needs to be based on the characteristics of the product, production requirements and mould design to decide. Reasonable cooling system design and temperature control measures can improve production efficiency, ensure the quality of the finished product, and reduce mould wear and production costs.
Professional manufacturer of thermoforming machines.
