A PET blowing machine is simply a machine used to make bottles.
However to further understand its concept and deeper meaning you will need to know what PET stands for. PET stands for Polyethylene terephthalate which is the plastic used to make these bottles. A pet blowing machine is a machine used to blow these pet bottles and convert them into a real bottle whose shape is according to the required specifications of an organization.
Pet blow molding is a process whereby you combine or join plastic parts to make a bottle or plastic parts and shapes. Pet blowing machines are also referred to as stretch blow molding machines, stretch blow moulding machines or bottle manufacturing machines.
To stretch simply means making something wider without the possibility of breakage and is what is done to the preform by the stretch rod.
Blowing involves a move that creates an air current and in this case it involves inserting air at a very high force into a hot preform, molding or moulding simply means giving shape or form to a hot material.
How a pet blowing machine works
Pet blowing is usually a two stage process and is the reason as to why the machine is referred to as a two stage pet blowing machine.
The first stage usually involves the preform injection while the second stage is what is usually referred to as the blow moulding process. Preforms are made first by the injection machine instead of pet blowing machine which is the first stage.
The 2nd stage is then done by the pet blowing machine which preheats and blow preforms into bottles.
The following auxiliary equipments are key accessories required in the processes and they include the air compressor, air filter, industrial filter and air drier.
These equipments for example the air filters and the industrial filters are paramount in keeping the bottles clean and free from dust and odors or any other contamination as cleanliness can be a major issue in the blow moulding processes.
The air drier usually ensures that any water vapor from the compressed air is completely removed.
How a blow molding machine works
There are three steps involved in the pet blow molding process and these steps give the full description of how the blow molding machine works.
The first step is usually the pre-heating, the second step is the blow-molding and the third and final step is ejection or removal of the bottle.
The pre-heating step or preform injection stage involves the plastic raw material being inserted into the machine and then is heated to about 300 degrees Celsius causing it to melt.
This is usually done by the injection molding machine which is a different machine. An injection molding machine usually has two important parts an Injection mold and ejector mold.
Once engaged the molten material is injected under high pressure into a sort of cavity making a preform. The injection molding machine is therefore used explicitly to form the preform.
The second stage now involves the blow molding. The preform is now inserted into the blow molding machine where it is stretched by the stretch rod and compressed air is blown into it pushing it out to the walls of the blow mold. The stretched preform in then cooled and hardened forming a bottle of the required shape and size.
The final stage is ejection which involves opening the pet blowing machine and removing the final bottle product. PET blowing machines are usually sold as per client’s requirements and are of two kinds, which are automatic and semi-automatic.
You should note that when using a semi-automatic blow molding machine a middleman will be required to pre-heat the preform in the blow molding process.
An automatic molding machine can do that with no need of a middleman and hence are usually sold at a higher price than its counterpart.
Applications of pet blowing machines
The pet blow molding machine is used and applied in a lot of areas such as the pharmaceuticals and medical industry, the agricultural industries, health and sanitization industries and the food industries.
It is used to make a variety of bottles for example; drinking bottles, plastic containers, pesticide bottles, oil bottles, shampoo bottles, detergent bottles, milk bottles, pharmaceutical bottles and last but not least the soda bottles like coca cola.
There are different types of techniques used in blow molding such as Extrusion blow molding, stretch blow molding and injection blow molding and depending on the technique used a lot of other products can also be made using blow molding machine for example toys, pipes and even hollow industrial parts.
Extrusion blow molding is usually used in production of complex industrial parts or shapes and also tube-like parts such as pipes, hoses and rods while injection blow molding is used in production of items such as pocket combs, automotive dashboards and bottle caps.
Blow molding machines are usually preferred to other methods because they reduce cost, provide high efficiency, quantity and quality, are easier to maintain and operate and are quite flexible.