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The role of Compressors in the PET Bottle Manufacturing Industry

PET Bottle Manufacturing Industry | KB Delta

PET, or polyethylene terephthalate accounts for around 70% of the total number of soft drink bottles manufactured around the world, comfortably making it the most popular material choice, ahead of aluminum and glass.

In an industry where there’s an abundance of compressor variations in use, from standard models to customized or bespoke systems, there are some common themes which unite all of them together. This is through the production of the various plastic bottles that line our supermarket shelves. In this article, we take a look at the role of compressors in the PET bottle manufacturing industry, as well as how to find quality compressor valve parts.


The Role Of The Compressor

There are various methods of creating plastic bottles that are all actively used within the PET bottle manufacturing industry today. Regardless of the type of system employed by a plastic bottle manufacturer, the compressor is always the component in the operation that requires the most care and attention in the overall process. This is because all processes require an injection of pressurized air in the shaping of the bottle.

Due to working under extreme conditions of heat, pressure and sustained periods of repetition, the compressor must accurately control the flow of air through the system on demand. As such, it is of critical importance to the success of the operation.

Traditionally the PET bottle manufacturing industry has been powered by reciprocating compressors which work through the use of pistons creating pressure within the system. These compressors were often required to produce in excess of 650 psi of plant air to produce the more intricate designed product. Although now companies have a preference for lower pressure systems to conserve energy requirements, and provide a more cost effective process. This has allowed the use of centrifugal compressors in the production industry, as although they can’t generate as much power as an equivalent sized reciprocating compressor, they contain can produce more airflow and more importantly, they’re more energy efficient.


The Importance Of The Compressor Valve

Compressor valves in the PET bottle manufacturing industry work under high pressure over long periods of time. This requires the parts to be extremely durable to perform consistently and efficiently. The role of the valve is to regulate the airflow within the PET bottle production system, supplying the air to the injector as and when it’s required, as well as controlling a working pressure within the system.

One of the main problems to be aware of in the manufacturing of PET bottles is the production of Acetaldehyde. This is an organic by-product which is formed on the plastic when the temperature exceeds 260°C, a temperature which is surpassed in the blowing process. To minimize the amount of AA created, a tight control of the air flow velocities is crucial to lowering the shear, which can contribute to overheating the material as well as potentially causing a problem with the shaping of the bottle during the molding. It is easy to understand that there is a need for high-quality parts within a compressor, but how exactly can you define which are of the highest grade?


What Constitutes Good Compressor Components for the PET Bottle Manufacturing Industry?

There are several criteria which must all be present for an engineered part to be considered of superior quality.  The first of which is the use of good source materials, as they are the foundation of its structural integrity. The choice of material here is also important as the part must be designed with its end use in mind, especially the conditions that it will be placed under during use.

The component must then be well engineered, using techniques and tools which are specialized and designed specifically for the parts being manufactured, before finally employing a batch sampling process to quality check the production line at random. This will verify that the components are indeed of the highest quality.

Additionally, if a bespoke part is being manufactured as opposed to a cataloged item, all factors surrounding the part needs to be carefully calculated and considered in a rigorous design process. This will ensure that the product specifications are met in theory, before testing their actual performance in practice.

All of these processes should be carried out by specialist manufacturers who should ideally have a wealth of experience within the industry, to utilize in creating premium products. These parts, therefore, may not be the cheapest options available on the market, but their true value in operation is of more value than any savings that can be made at this stage for your business.


Extending The Expected Lifetime Of Machine Parts

Even using the highest possible standard of component, all parts are subject to deterioration and decay. A quality parts manufacturer or expert technician will be able to advise you as to how long systems and parts, in particular, can be safely expected to retain optimal functionality. There are some measures that can be implemented to help reduce the wear of machine parts, and in doing so, increase the time between maintenance and part replacement cycles.

A reduction in the blow pressure can often be applied to equipment by calculating the minimum pressure required to blow bottles to the required quality levels, and eliminating any artificial demand on the system.  This serves to lower the amount of heat inside the compressor, as well as reducing the energy cost to the business. However it can also have an adverse effect on production speed and requires careful planning and execution by a trained engineer to ensure optimal performance is achieved.


Reducing The Compressors Workload

There are of course many different factors which contribute to the formation of the perfect PET bottle, but one of the easiest ways to improve the overall system performance is to reduce the amount of stress placed on the compressor. By monitoring the pressure of the compressor’s output against the pressure reaching the injection point, will then detect unexpected pressure drops within the system that can then be eradicated to maintain a high level of operating efficiency. Pressure drops mostly arise from faults within the actual molding machine, but can also occur in the pipe network which transports the compressed air from the compressor.

By re-locating the compressed air storage tank as close to the molding machine as possible and using a larger storage tank will also reduce the drop in pressure as it adds further support to the air flow during each blow cycle. Both of these actions serve to reduce the workload placed upon the compressor and as such, reduce the amount of wear suffered by the components.

In implementing any of the above actions, however, you will increase the need for tighter control and monitoring measures across the system, as the whole process becomes more finely balanced with less margin of error in production. A further reason why there is a great need for using the highest quality parts available for PET bottle manufacturing industry.

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