Plastic injection molding is a common process in manufacturing, and it can be used to produce just about anything. To create a part, molten plastic is injected into a hollow mold, where it is formed and cooled before being ejected from the cavity. Plastic injection molders make a seemingly limitless range of products, from fishing tackle boxes and kayak paddles to tooth brushes and miniscule medical devices.
Technological trends in plastics manufacturing are driving the costs of production down. In industrial PET blow molding specifically, two innovative techniques have had major impacts over the last 15 years: “light weighting” the plastic bottles, and recirculating high-pressure compressed air. Both have helped to improve the energy efficiency of PET blow molding by reducing compressed air requirements dramatically.
PET Power Containers, a Canadian manufacturer of PET plastic containers, had plans for expanding its operations with the addition of more blow-molding equipment. Before the expansion could happen, however, the company needed to assess its compressed air system. Based in Vaughan, Ontario, PET Power provides a dizzying array of differently shaped and sized plastic bottles. Their operations run 24/7, and compressed air plays a key role in their primary manufacturing applications, including PET blow molding, PET preforming, and labeling bottles.
A Canadian fiberglass plant has completed a lengthy compressed air improvement journey and achieved significant efficiency gains by applying “the systems approach.” Along the way, the company ran across many frustrating problems, the solutions to which were only determined after the entire system was monitored holistically using data loggers. The overall compressed air audit led to a reduction in energy usage of 48 percent, yielding savings worth $17,500 per year. The project also qualified for a large utility incentive of $32,000 with a calculated payback of 4.4 years.
Sometime in mid-2015, I received a call from a project engineer at a major plastics firm. He had a troubling issue with one of his PET bottle plants. The bottom line was this: They could not run all five high production blow-molding machines at one time—even though they were able to do so 18 months previously.
In 1979 I received a call from a business friend that had just purchased his first single-stage base cup blow machine. He was surprised to find out that he actually needed something more than 100 psi of plant air to blow bottles. This was my entry into engineering a polyethylene terephthalate (PET) compressor system. Since then, I have engineered and delivered over 350 systems—from Tobago to Tibet—and many locations in between.
The beverage industry has been using polyethylene terephthalate (PET) 2-liter plastic bottles primarily for packaging carbonated soft drinks since the 1970s. As that market has grown to encompass bottled drinking water, stretch blow-molding machines continue to produce those plastic bottles. The concept is simple: A pre-form plug is inserted into the blow molding machine heated, and compressed air is injected, “blowing” into the pre-form to create the bottle.
Compressed Air Best Practices® Magazine interviewed Michael Jones, Corporate Energy Team Leader, from Intertape Polymer Group (IPG). Intertape Polymer Group (IPG) is a manufacturer of tapes, films, woven fabrics, and complementary packaging systems for industrial and consumer use. The company operates 10 production plants and employs approximately 1,800 people. IPG has developed a robust energy management program by using ENERGY STAR energy management tools and actively participating in the ENERGY STAR partnership. IPG is receiving ENERGY STAR recognition for the growth of its energy program and leadership as a medium-sized manufacturer.
Stretch blow molding equipment requires a significant amount of energy—both compressed air and electrical—to produce bottles. Creating an effective and efficient process, as well as monitoring and maintaining optimal process settings, can result in significant energy cost reduction. These efforts will also help produce containers that meet all of the required quality standards.
Two years ago, sales were picking up and we began operating six extrusion lines on most days. We had to bring in some portable chillers, to keep up, and we started looking at buying a larger cooling system. We wanted to get rid of the portable chillers and have room to grow into four more extrusion lines. The new system we looked at was a 100-ton system that would have cost us around $150,000 in capital and installation and with a larger monthly electricity bill. We were about to buy the new 100-ton chiller when our President, Abe Gaskins said, “Hold-on, can we replace the Liquid Ring pumps with something that doesn’t consume water”? That was our “Eureka!” moment.
This plastic extrusion factory spent an estimated $180,711 annually on energy to operate the compressed air system at their Midwestern facility. Based on the air system operating 8,760 hours per year, the group of projects recommended below could reduce these energy costs by an estimated $116,520 or 67% of current use. Estimated costs for completing the recommended projects total $20,100. This figure represents a simple payback period of 2 months.