Blow molding process is divided into four basic steps: First, the formation of tube; the second is closed after the mold in the compressed air into the inflatable; Third, cooling stereotypes; four venting Kai mold products.

·Blow molding process
1, injection blow molding process
The injection blow molding process is to inject the molten plastic in the injection mold into a tubular parison. After the mold is opened, the tube blank is left on the core lock, and the blow mold is closed while hot air is introduced from the airway 0.2 ~ 0.7MPa of compressed air, the parison blown into the shape of the cavity, and finally in the holding pressure conditions can be obtained by cooling stripping products.

2, extrusion blow molding process
Extrusion blow molding process is extruding the tubular parison, hot parison into the blow mold, and then from the blow mold airway into the parison into the 0.20 ~ 0.69MPa Of the compressed air, so that the billet blown to the cavity shape, the final cooling conditions in the holding pressure after stripping can be products.

3, stretch blow molding process
Tensile stretch blow molding process includes: injection parison directional stretch blow molding and extrusion parison directional stretch blow molding.
Injection-oriented parison oriented stretch blow molding process is: the first injection of a bottom parison, and then heated to the appropriate stretching temperature, into the blow mold by drawing rod axial tensile, tensile rate Is 1 to 2 times the same time, the introduction of compressed air has been axial stretch of the parison, the cooling after demoulding products.

4, multi-layer blow molding process
Multi-layer blow molding is the injection blow molding and extrusion blow molding developed on the basis of the process, but its products from the single layer into a multi-layer wall only.

5, large-scale blow molding process
Large-scale blow molding process technology is the key: high-speed forming parison and control wall thickness uniformity, reducing the deformation of the container. This requires parison temperature control to be uniform, mold design must be conducive to stripping.

6, process control factors
Factors affecting the blow molding and product quality are: parison temperature, mold temperature, cooling time, drum gas rate, blowing air pressure and inflation ratio.
a, Parison temperature
The parison temperature is generally controlled between the glass transition temperature and the softening temperature (or melting temperature), and is softened to the softening temperature side.
b, Mold temperature
Die temperature and raw materials of the glass transition temperature (Tg), Tg higher, the mold temperature can be higher; the other hand, the mold temperature should be lower.
c, Cooling time
The cooling time of the hollow blow molding is generally 1/3 to 2/3 of the molding time, in order to prevent the deformation of the product caused by the elastic recovery effect of the polymer.
d, Blowing rate
Blowing blow molding hollow blower rate should be as large as possible, this will shorten the inflation time, to achieve a more uniform wall thickness and good container surface.
e, Blow molding air pressure
Blow air pressure and plastic melt viscosity, product size and parison wall thickness and so on.
f, Blow up ratio
Blow ratio refers to the product of the outer diameter (non-cylindrical products to the largest horizontal size) and the parison outer diameter ratio.

·Blow molding equipment
Typically, the main blow molding equipment for the injection machine and extruder, followed by blow mold. Blow mold is often composed of two half-mold, because the pressure is not blow mold, commonly used mold materials are aluminum, zinc alloy, beryllium copper, cast iron and steel.