Blow molding machine, also known as hollow blow molding machine, a kind of rapid development of plastic processing methods.
Thermoplastic resin by extrusion or injection molding of plastic parison tube, hot (or heated to softening state), put in split cavity, mold closing immediately after ventilation with compressed air within the parison, make plastic parison swell and clingy wall in the mold, the cooling mold release, the products have all kinds of hollow.
Blown film manufacturing technology on the principle and hollow blow molding is very similar, but it does not use the mould, from the perspective of classification of plastics processing technology, molding process is usually included in the extrusion of blown film.
What is Blow Molding?
Blow molding is the process of forming a molten tube (referred to as the parison or preform) of thermoplastic material (polymer or resin) and placing the parison or preform within a mold cavity and inflating the tube with compressed air, to take the shape of the cavity and cool the part before removing from the mold.
Any hollow thermoplastic part can be blow molded. Parts are not just limited to bottles, where there is one opening and it is usually smaller in diameter or size than the overall body dimensions. These are some of the most common shapes used in consumer packaging, however there are other typical types of blow molded parts, including, but not limited to:
Industrial bulk containers
Lawn, garden and household items
Medical supplies and parts, toys
Building industry products
Automotive-under the hood parts
Appliance components
Blow Molding Manufacturing Processes There are three main types of blow molding:
Extrusion blow molding
Injection blow molding
Injection stretch blow molding
The main differences among them are the method of forming the parison; either by extrusion or injection molding, the size of the parison and the method of movement between the parison and blow molds; either stationary, shuttling, linear or rotary.
7 Basic Facts about Blow Molding
1. What is a blow molding?
Blow molding is a manufacturing process that makes it possible for hollow plastic parts to be formed.
In very basic terms, plastic is melted down, clamped into a mold, and then air is blown into it. All types of hollow plastic parts can be made through this process.
2. What are the types of blow moldings?
Extrusion blow molding
Injection blow molding
Stretch blow molding
Reheat and blow molding
3. Extrusion blow molding
In extrusion blow molding, a hot tube of plastic material is dropped from an extruder and captured in a water cooled mold. Once the mold is closed, air is injected through the top of the container.
When the hot plastic blows up and the mold material freezes, it’s able to maintain its shape.
4. Injection blow molding
In this method, hot plastic material is injected into the part of the mold that creates the neck. The injected material is then taken to the next station on the machine where it is blown up into the finished container like in the extrusion blow molding process.
5. Stretch blow molding
This method is mostly used for producing bottles commonly used for water, juice, and other similar products. The injection stretch blow molding machinery molds a preform, which is then transferred to another station where it is blown and then ejected from the machine.
6. Reheat and blow molding
This is a type of stretch blow process in which a preform is injection molded by an outside vendor.
There are many companies who produce these stock preforms on a commercial basis.
Factories buy the preform and put them into a machine that reheats them so they can be blown.
7. What are the advantages of blow molding?
A few advantages of blow molding:
Less time spent on the mold-creation process
Faster turn-around times
Well suited for high production rates using a variety of materials
Blow molding tools are fairly inexpensive compared to other molding equipment