We pick up plastic bottles every day, but we rarely think about how they are made. Blow molding technology allows us to create hollow polymer products - from shampoo bottles to canisters for machine oil. This is an industrial method in which a three-dimensional form is obtained from a flat blank.
Contents
Three Main Methods of Blowing
Manufacturers use different technologies depending on the type of product.
Extrusion blow molding works like this: the polymer melt is squeezed through a ring head, forming a tube. The tube is then placed in a mold, and compressed air is supplied inside. The material is stretched and takes the shape of the mold. At the end, the product is cooled and removed. This method is used to make canisters, technical containers, toys. The method is suitable for large products of complex shapes.
Injection blow molding is arranged differently. First, a preform is cast — a blank with a ready-made neck. Then the preform is heated to a plastic state, placed in a mold and inflated with compressed air. After cooling, the finished product is obtained. This is how bottles with a perfectly smooth neck for screw caps are made. OOO "Preform Plant" specializes in the production of blanks for this method.
Stretch blow molding involves additional mechanical stretching. The PET preform is heated, stretched vertically with a special rod, and simultaneously inflated horizontally with air. Double stretching makes the material stronger. This is how soda bottles are made, which do not deform from internal pressure.
What happens to the material
The blow molding process involves stretching of the polymer's molecular chains. This phenomenon underlies the entire technological process. When heated to the plasticity temperature (around 100°C for PET), the long chains of molecules line up in the direction of stretching. After cooling, this orientation is preserved, giving the material new properties.
A lot depends on the correct drawing: the strength of the product, the uniformity of the wall thickness, transparency, barrier properties. The drawing coefficient - the ratio of the surface area of the finished product to the area of the original blank - usually ranges from 8 to 12 units for standard bottles. In stretch blowing, a distinction is made between longitudinal and transverse drawing, their ratio directly affects the mechanical characteristics of the finished container.
If the material is stretched too much, the bottle will break due to excessive thinning of the walls and damage to the integrity of the molecular structure. If not stretched enough, it will be heavy, with an overconsumption of raw materials, and will also lose transparency due to insufficient orientation of the molecules.
Technologists carefully calculate:
- temperature conditions;
- air supply speed;
- blow pressure to achieve optimal performance.
Modern blow molding machines allow these parameters to be programmed with high precision for each type of preform.
In the production of large containers, intermittent extrusion is used - feeding the material with pauses. This allows you to create products with different wall thicknesses, save raw materials, and make durable handles and bottoms. Controlled extrusion makes it possible to strengthen those areas of the product that experience the greatest load:
- bottom;
- shoulder area;
- place of transition to the neck.
Blow Molding Machines
There are different types of blow molding machines. Rotary ones are used for mass production - they produce tens of thousands of bottles per hour. Linear ones are suitable for medium volumes with frequent mold changes. Laboratory ones are used to develop new products. In modern equipment, all processes are automated: from heating the blank to packing the finished bottles.
Blow Molding Materials
Thermoplastic polymers are used for blow molding:
- PET (polyethylene terephthalate) - for transparent bottles.
- PE (polyethylene) - for canisters, bottles of household chemicals.
- PP (polypropylene) - for heat-resistant containers.
- PVC (polyvinyl chloride) - for special applications.
OOO “Preform Plant” produces <PET preforms - blanks for the production of bottles for various purposes.
Quality control of bottles
Many parameters are controlled during the production process: product weight, dimensions, wall uniformity, strength, tightness. Each batch is tested for compliance with technical requirements.
Modern trends
Today, manufacturers strive to reduce the weight of bottles, use recycled plastic, and create biodegradable packaging. OOO "Zavod Preform" follows global trends and offers customers modern solutions for product packaging.
What we offer
Our company produces preforms of various sizes, which are used for the production of bottles by blow molding. We supply products to manufacturers of beverages, oils, household chemicals.
Advantages of working with us:
- Modern equipment HUSKY, Battenfeld for precision casting of preforms.
- Strict quality control of raw materials and finished products.
- Technological support at all stages of cooperation.
- Development of individual solutions for the client's needs.
- Guaranteed compliance of preforms with the parameters of your blow molding equipment.
Contact the specialists of LLC « Preform Plant» to select the optimal preforms for your tasks. We will help you choose the appropriate blanks taking into account your production capabilities and requirements for the final product.