PET Bottle Blowing Machine Buying Guide

Did you know that a bottle made using a PET bottle blowing machine can withstand an internal pressure of up to 40 bar？ It is due to the biaxial orientation process that increases the strength of the PET material at the molecular level. It is the machine used to create pressurized carbonated drinks that maintain the majority of their initial carbonation even after 14 weeks of storage. Buying a PET plastic bottle is a massive capital investment. It impacts how the factory will operate in the future.

It impacts everything from production efficiency, energy footprint, and product quality. To ensure that we make the right decision, we must know the following key aspects of the PET blow molding machine:

• Mechanical Synchronization of Parts
• Thermal Control of the Work Piece
• Modular Flexibility for Upgrades/Maintenance

We will cover all these aspects and more in this guide. It is designed to provide professionals with the right technical framework to judge the performance of a stretch blow molding (SBM) machine.

Understanding Technology: Process Types

♦Single-Stage vs. Two-Stage Systems

When diving deep, we can see that these machines have two main types. Both of them are used for their specific applications.

✔Single-Stage

It is the process in which the creation of the preform and its expansion into a bottle happen together in the same machine. The preform is still hot during its creation, therefore it does not require any reheat process, improving the energy efficiency of the machine. These machines create better threaded neck quality because the plastic piece is held in its original holder until the bottle is finished. It is ideal for cosmetic bottles as it makes bottles from gateless preforms. There is no visible injection point mark.

✔Two-Stage Systems

Two stage system divides these tasks. The tubes (preform) are made earlier in bulk quantities. For fast paced beverage industry, it is considered the go-to method. They provide better production rates when a large number of bottles are required. As the blowing setup is separate, it can run at its own pace without having to wait for the slow injection molding.

♦Linear vs. Rotary Configurations

When it comes to the bulk bottle making process, factories use either a linear or a rotary configuration for their PET blowing machine. The machines vary in layout, speed and operational flexibility.

✔Linear Configuration

The linear configuration allows easy access to the various parts of the machine. The engineers can access the heating zone and mold stations for preventive/corrective maintenance jobs. They may contain around 1-12 individual bottle-shaping cavities. The number of molds on the machine is limited. It means they are great for medium sized manufacturing facility. In comparison to the rotary configuration, they have a modular approach that allows operators to swap out parts much faster when changing the shape of the bottle. 

✔Rotary Configuration

Configuring the machine in a circular layout allows a compact design. It takes up lower real estate while providing production rates of 80,000+ bottles per hour. The rotary setups operate with a non-stop movement. It does not pause and push forward like linear machines. The process runs much more smoothly, reducing the mechanical shock on the bottles and machine parts, extending its life. They can produce twice as many bottles in comparison to linear setups.

Key Engineering Selection Criteria

▶1. Determining Production Capacity and Machine Sizing

When selecting a machine for your factory, you should look for production rates that are higher than your requirements. When your factory is running at its full capacity, the machine should be running at 85% of its maximum production rate. These will ensure that you can have some buffer in case a large order comes in. These machines have a typical production rate of 1,000-3000 bottles per hour for every cavity. The size of the bottle/cavity determines the bottle production rates.

▶2. Operating Speeds and Smart Automation

The time it takes to form a bottle is known as the blowing cycle. It usually takes around 1.5 to 8 seconds. The exact cycle time depends on the thickness of the bottle walls, the preform quality and the chilling system's capability to solidify the plastic. To ensure that the machine stays on its production rate, there are vibrating conveyors and sensors fully automating the setup. These ensure that all preforms are properly oriented before they go into the oven.

Modern machines use servo motors and a variable pitch device between the preforms as they move. By keeping the preforms closer in the heating phase, there is better space utilization in the heating oven.

▶3. Precision, Timing, and Machine Coordination

To ensure that all the mechanical movements in the machine are synchronized and well-coordinated, modern machines use all-electric servo systems. They ensure mold clamping, preform transfer, and stretching happen in sync. Using electrical motors removes jerky movements in comparison to pneumatic or hydraulic systems.

The servo motors have extraordinary precision, which can go in fractions of microseconds. The exact time is vital to ensure that the bottle has a uniform thickness.

▶4. Smart Controls and Producing Flawless Details

The most advanced PET bottle blow moulding machines utilize a PLC controller that allows engineers to tweak the process on the go. They can change the heating and stretching process as per the requirement. It means you can produce different sizes and weights of preform by saving different profiles for each process. When the bottle is formed, the servo-driven clamping units apply preise pressure during the final blow. It results in perfect seam quality and embossed logo quality.

▶5. Waste Reduction and Simplified Maintenance

In case of emergency stops, servo-based machinery provides much better performance in waste reduction. It can reduce the preform scrap by 50%.

Optimizing Production Efficiency

• Managing Compressed Air: Modern PET bottle blowing machines can capture and reuse more than 25% of the air used in the high-pressure blowing system. They use it in the pre-blowing phase.
• Smart Heating: Near-Infrared (NIR) based heating cuts energy bills by 30% and provides a 50% faster operation than traditional infrared lamps. They also allow controlled heating in different zones. The neck could remain cool while the body reaches 100 °C.
• Rapid Cooling: To solidify the plastic once it hits the molds inside contours is vital for proper shaping. The molds are kept cold with water flowing at around 10 °C. It stops the material from geting cloud or brittle.

Maintenance and Technical Support

◇Smart Monitoring and Proactive Problem Solving

To ensure that the machine works at its optimal performance, they need to monitor its parameters. Modern machines come with IoT connectivity. It allows the management to monitor the machine performance remotely. It also allows 24/7 remote technical support. With the help of computers, they can detect the sensor drift, which can cause the production process to slow down.

◇Machine Testing and Staff Preparation

The best PET bottle blowing machine manufacturer will test the machine for a continuous 72 hours of operation and test it with real plastic before shipping it. These are called factory tests. It allows rapid commissioning of the equipment and testing. 

◇Parts Management and Long-Term Maintenance

It's vital that the machine is made with standardized components. It includes Japanese self-lubricating bearings and other parts that are readily available through local sourcing. Infrared lamps after 8,000 hours of operation may require replacement. Do not wait for them to burn out completely, as it will halt the production process.

Conclusion

When selecting a PET bottle blowing machine its vital that you find the balance between initial investment and long-term performance. Consider everything from maintainability, advance monitoring and smart control systems. To get the best performance out of a machine, go for all-electric servo precision, air-recovery modules and modular mold designs in your machine. To find them all at one machine, consider Vfine Machinery as your manufacture.

With 20years of experience, our lineup includes high-speed models, machines that make voersized container and specific designs based on the requirement. Visit our products website or contact us for more details.

FAQs

1. How long does a typical bottle blowing cycle take?

The complete bottle-making process for each bottle takes around 8 seconds. These high production rates are achieved through the use of high-speed rotary systems. They allow small-volume bottle production. For larger bottles, the production rate may change.

2. What causes a "hazy" appearance in blown PET bottles?

The hazy appearance can happen due to two reasons. One is improper temperature control, causing crystallization. Second is if the bottle is made from a resin that contains high moisture. The moisture should remain under 50ppm with proper dryer operation.

3. Can I use one machine to produce multiple bottle sizes?

Changing bottle sizes in a single machine is possible. The process requires changing the mold. The complete transition to the better bottle design may take a maximum of 30minutes with trained operational personnel as long.