PSI-Polymer Systems Gear Pumps Feature Multiple Manifolds For Fast Changeovers – Reducing Downtime and Increasing Product Quality Conover, NC (August 15, 2014)
PSI-Polymer Systems has been an industry leader in the production of extrusion gear pumps with manifold options for many years. Recently, they have been called upon to customize their product for several challenging, cutting edge applications, and their engineers were up to the task.
One such challenging application with which they were presented involved a complex manifold system with banks of four gear pumps for each extruder. The valving, designed by PSI, was capable of adjusting and even stopping the flow to each pump. The application involved both a twin-screw extruder and a single-screw extruder, with the twin-screw requiring varied feed to the system to supply the correct mixing. The plastic material being used was PEEK, a challenge to process due to the sensitivity and high temperatures needed. Because PEEK easily degrades, a custom design was necessary to ensure proper flow geometries. PSI designed the flow areas in the manifold so there were no potential degradation areas for material inside of the manifold block. Adding to the challenge, the customer was using the PEEK to coat fiber-filled material, and could not allow more than 0.5% variance.
PSI designed a custom control system for this application, featuring custom written code for the controller to help handle all of these requirements. They set up 4 valves upstream with sealing mechanisms, each contributing to the custom control. If one pump is shut off, the controller senses it and compensates flow. This allows for the proper flow geometry, super critical tolerances, and easily less than 0.5% variance. The system worked so well that the customer bought two spare pumps that they could swap in and out.
For a second application, a customer was trying to produce 6 plastic strapping bands from a single extruder. They were attempting to control all 6 strands with one gear pump; the problem was they needed to constantly adjust flow and after making these changes, temperature profiles and flow profiles would not be consistent. The result was inefficient production and an unacceptable amount of scrap material. PSI was called upon to analyze and solve the problem.
After analysis, PSI recommended and provided a solution involving the use of 3 gear pumps with manifolds. Two strands per pump are controlled with the new PSI unit. A left-right-center flow provides equal flow to each channel, better flow geometries, better material distribution, and less material gauge variation. The transitions, manifolds and adapters provided by PSI keep flow equalized, resulting in identical product quality. PSI also provided a custom pump system controller for this application. It works with all leading platforms and can communicate in multiple languages.
An additional benefit of the PSI solution is the processor now has the flexibility to use additional regrind, saving them money. The main material being used is virgin PP, but due to the better control of the process they can produce above-spec material with in-house regrind.
“At PSI we are proud to be able to design these custom solutions that help solve our customer’s complex applications,” said Glenn Woodcock, President of PSI-Polymer Systems.