What is the impact of Suzhou blow molding processing effect

Suzhou blow molding is one of the third commonly used plastic molding methods and also a rapidly developing plastic molding method. Plastic products are widely used in various industries, and it can be said that Suzhou blow molded products have integrated into our lives.

Suzhou blow molding is a method of forming hollow products by placing extruded or injection molded pipe blanks in molds, blowing compressed air into the pipe blanks to make them tightly adhere to the mold cavity wall, and then cooling and demolding. This molding method can produce various packaging containers such as bottles, pots, buckets, daily necessities, and children's toys.

Influencing factors:

1) Blowing pressure

In blow molding, compressed air has two functions. Firstly, it causes the tube blank to expand and tightly adhere to the mold cavity wall, forming the desired shape; Secondly, it has a cooling effect.

Depending on the type of plastic and the temperature of the preform, the air pressure also varies, generally controlled between 0.2-0.7 megapascals. The most suitable pressure is to ensure that the shape, pattern, and other features of the product are clearly visible after molding.

For those with low viscosity and easy deformation, take lower values; For plastics with high viscosity and modulus, take higher values; Large volume and thin-walled products should be subjected to higher pressure; Small volume and thick walled products use lower pressure.

2) Inflation speed

In order to shorten the blowing time and achieve a more uniform thickness and better surface of the product, the inflation speed (the volume of air flowing through per unit time) should be as high as possible, but it should not be too high, otherwise it will have adverse effects on the product: firstly, it will create a vacuum at the air inlet, causing the concave part of the billet to sink, and when the billet is completely inflated, the concave part will form a diaphragm; Secondly, the billet in the mouth mold part may be pulled apart by extremely fast airflow, resulting in waste.

To achieve this, it is necessary to increase the diameter of the blowing tube or appropriately reduce the inflation speed.

3) Inflation ratio

The ratio of the size of the product to the size of the billet is usually referred to as the inflation ratio. When the size and weight of the billet are constant, the larger the size of the product, the greater the blowing ratio of the billet. The blowing ratio is determined based on the variety and properties of the plastic, the shape and size of the product, and the size of the preform. Usually, the inflation ratio is controlled at 2-4 times.

4) Mold temperature and cooling time

To ensure product quality, the temperature distribution of the mold should be uniform, and the mold temperature is generally maintained at 20-50 ℃. If the mold temperature is too low, it will reduce the extensibility of the plastic at the clamp, making it less prone to swelling and thickening the product in this area. At the same time, it will make molding difficult, and the contour and pattern of the product will not be clear. The mold temperature is too high, the cooling time is prolonged, and the production cycle is prolonged. The product undergoes demolding deformation and shrinkage increases.

The temperature of the mold depends on the type of plastic. When the glass transition temperature of the plastic is high, a higher mold temperature can be used; On the contrary, try to reduce the mold temperature as much as possible.

Usually, as the wall thickness of the product increases, the cooling time prolongs. Sometimes, in addition to cooling the mold, internal cooling of the molded product can also be performed by introducing various cooling media (such as liquid nitrogen, carbon dioxide, etc.) into the product for direct cooling.

5) Molding cycle

The cycle of blow molding processing in Suzhou includes processes such as extruding the billet, cutting the billet, closing the mold, blowing air, cooling, releasing air, opening horizontally, and taking out the product (subsequent trimming, matching, and packaging are included separately).