Blow molding processes to help reduce scrap and save energy

Finding the right auxiliary equipment for your facility is imperative to running a smooth operation, and while the blow molding process represents a relatively small segment of the plastics industry, it’s still extremely important. Injection blow molding is used almost exclusively to produce polyethylene terephthalate (PET) plastic bottles, while extrusion blow molding primarily creates large products ranging from children’s toys and play structures, to oversized drums, gasoline tanks, and air manifolds. No matter what type of blow molding process a facility utilizes, Conair Group is here to help find ways to reduce scrap and energy consumption.

In extrusion blow molding, a certain level of scrap is expected as a by-product of the process, but certain methods can be utilized to better reduce the amount of scrap being produced. Preforms are unblown tubes with the threaded ‘finish’ molded in and are often rejected due to minor defects. However, they can be reheated and blown in a separate operation before being granulated and reintroduced to the molding process. Even though processing considerations limit the amount of regrind that can be used in the blow molding process, this trend of using scrap preforms in injection blow molding is an excellent way to reduce scrap, keep the process more sustainable, and save the company money.

Properly drying out PET regrind is necessary before processing, so having the right auxiliary equipment is important. PET is hygroscopic and will absorb moisture from the air – if it is processed without proper drying, the moisture inside of it can cause structural and cosmetic flaws. Conair Group has high-performance desiccant dryers that offer complete control over the four fundamental drying parameters (temperature, dew point, time, and airflow) so processors can be sure their components are being made without any flaws.

Another way to reduce the use of virgin material is to use post-consumer-recycled resin or PCR. With the considerable rise in environmental consciousness (and government mandates), many brand owners are specifying that a certain percentage of PCR must be incorporated into bottles and other blown containers being produced. PCR is often packaged like virgin materials, and material-handling requirements are mostly the same, making the manufacturing process easier.

A second important blow molding trend driving auxiliary equipment decisions is the increase in efforts to reduce energy consumption. Utilities, especially electrical power, are one of the highest costs in most blow molding applications, and drying is a major contributor. While drying is not normally required when HDPE and other polyolefins are processed in blow molding, it is still critically important in the processing of PET.

Sizing the drying system properly is always the first step in minimizing energy consumption. Many times, dryers are oversized or selected based on maximum processing capacity requirements, which are only rarely needed. A properly-sized system can save a significant amount of time, money, and energy. Desiccant drying systems, for example, are the gold standard in drying and use up less energy than other dryers. The Conair Optimizer dryer control software, coupled with the unique Conair Drying Monitor, can automatically adjust drying conditions so energy consumption is kept to the absolute minimum required for the application.

The desire for environmental consciousness and sustainability often creates trends toward reducing material use and energy consumption, and this is certainly true when it comes to blow molding. Conair Group understands the critical role auxiliary equipment plays in blow molding, and our team is dedicated to helping processors manage their operations for maximum efficiency and profitability. 

Learn more from the auxiliary equipment experts at Conair Group.