Intensive Cooling Technology
An extremely high performance cooling system, known as the “Herrington Stack”, was developed and patented by Mobil Chemical back in the 1970’s. Over the years, these stackable cooling systems produced billions of pounds of product for Mobil, but unfortunately, with downsides…high frequency gauge variation, high noise levels and difficulty in stabilization. Addex’s Intensive Cooling Technology picks up where the Herrington Stack leaves off, and takes it way beyond. After a very intense R&D program here at Addex, we have solved the vibration and stability problems, and even added a stability and efficiency control capability!
It begins with a completely new Intensive Cooling Technology design, arranged in a stackable configuration to achieve higher output rate, each with divergent air flow along the bubble, both upward and downward, to provide high film holding forces and peak cooling efficiency. The high performance divergent cooling elements are assembled using simple spacer pipes that also provide a common feed of cooling air to each cooling element level. The stack mounts directly to the top of the die, forming a Short Stack topped with an Intensive Cooling Addex dual flow air ring.
Next, an enclosure is added to fully surround the stack, replacing the surrounding atmosphere with a very stable controllable ambient pressure. Each enclosure includes a very simple flapper style flow buffer and multiple low pressure, bladed fans to operationally set the pressure differential between the inside and outside of the bubble. The Intensive Cooling Technology includes easy-to-interpret operator feedback and adjustment for optimizing the stability and cooling efficiency of this enclosed, stacked cooling system.
The very high performance of the Intensive Cooling stacked system is assured by the multitude of divergent cooling elements, each providing a 10-15% increase in output rate over our conventional Addex dual flow air ring. Four (4) elements are provided standard, yielding a 30-60% increase in output, with high film quality assured by the enhanced stability of the Intensive Cooling Multi-level Stacked Technology design. Two (2) cooling elements are the minimum, but generally any number can be stacked to achieve the desired output.
Note: IBC output is considered separately and is added in addition to Intensive Cooling Dual Flow Air Ring output.
A Brief History of Cooling
by Bob Cree 2016
To remain competitive, blown film manufacturers must maximize output and quality, however cooling system performance has been a significant limiting factor…until now.
Many different commercially available cooling systems have been developed by OEMs, both external and internal to the bubble. To varying degrees these systems have achieved success. Internal cooling (IBC) systems have evolved significantly over the years, and together with external systems, generate significant additional output. Unfortunately, IBC systems cannot always be used, depending on such factors as operator skill, thermoplastic material properties, and the physical size and design of the associated die. In contrast, external systems are the cooling workhorse for the industry, providing the majority of cooling and stabilization across the full range of Blown Film processes.
The earliest external cooling element, known as a “Single Flow Air Ring”, still in common use today, applies a single flow of cooling air around the bubble, and typically produces good film quality, but at lower output rate. By applying well known Bernoulli and Coandă principles, additional flows of cooling gas have been added over time to create various multi-flow cooling element designs, such as “Dual Flow”, “Triple Flow” or even “Quad Flow” air rings. To gain additional output and/or stability, various cooling elements have been paired, depending on the application, to form what is generically known as a “Tandem Air Ring”. Typically air rings are fixed in place, but in some cases are height adjustable above the die, to allow extending the cooled surface area along the bubble. This can produce even higher output, but also results in greater unsupported surface area above the die, which unfortunately, is the hottest and weakest portion of the bubble. This can lead to degraded stability, making it more difficult to operate the extrusion line.
And then there are cooling systems developed by end users…one in particular stands out…back in the 1970’s, Jack Herrington of Mobil Chemical developed a very high output cooling system called the “Herrington Stack”, publicly acknowledged in a series of patents, with outputs that were truly extreme, well in excess of anything else ever seen in blown film production. This system literally takes cooling to the limit of what the polymer can handle before ripping to pieces, and imparts enhanced physical properties to the film due to its ability to impose a preferred shape to the bubble. This cooling system has produced billions of pounds of product, but unfortunately, with significant downsides…high frequency gauge variation, high noise levels and difficulty in stabilization, which has limited this design to just a few select blown film applications. With the huge upside of extremely high output, many attempts have been made over time, to try and solve these problems…
This is the genesis of Intensive Cooling Technology.
INTENSIVE COOLING AIR RINGS
All Addex air rings—LFR, MGC and EGC—are now available with Intensive Cooling technology!
Addex has taken air ring technology to a new level by integrating Intensive Cooling technology directly into the dual-flow air ring design. The new Intensive Cooling air rings typically deliver 10%-15% or greater output and better bubble stability—over and beyond Addex’s already high performance, industry-standard dual-flow air ring design.
This newly adapted, patent-pending cooling technology replaces the standard lower lip with a single Intensive Cooling element on Addex’s dual-flow air ring system. The previous low-velocity lower lip is transformed into a high-velocity air stream, creating two primary locking points instead of just one, to significantly improve bubble stability. The Intensive Cooling air rings also include all of the secondary air collar locking points found with the original air ring design. The units are simple and operator friendly, allowing a broad range of processes, blow-up ratios, thicknesses, and materials with minimal adjustments.
The new Intensive Cooling technology applies to all of Addex’s air ring products including automatic profile External Gauge Control (icEGC), Manual Gauge Control (icMGC), and Laminar Flow (icLFR) air rings.
Guaranteed 10% – 15% greater output when Addex air rings are upgraded to Addex Intensive Cooling air rings!