The Practical Processor - November 2010

Your Processing Questions Answered

Q. What would you recommend to assist me with my mold-cooling problems, which I attribute to major calcium buildup. Short of investing in big-money chemical injection units for my tower water system, or complete disassembly of the molds and machining out the lines, is there a product/solution that can be closed-loop cycled through these molds to remedy this issue?
—Jason E. Huckabee, vp, operations, Hayes Industries, Ltd., Sugar Land, TX

A. If you go outside our “slow-to-pick-up-technology” industry, there are some amazing technologies that are relatively inexpensive. To prevent calcium scale buildup, all you need is a water softener, which exchanges the calcium ions for something else. Some plants can get by with a $200 water softener from Home Depot, Lowes, etc.

Moving on to fix the plugged or restricted water channels:

  1. Look in your yellow pages for water-treatment specialists. There should be a number of firms listed, though indentifying a competent one may be a problem. Make sure they are properly trained and have significant time in the field.
  2. Find a local water/steam plant and ask them whom they use. Every plant that generates steam will be concerned about calcium scale buildup.
  3. Find an oil-service company like Haliburton, Baker Hughes, Dowell etc. These folks will have their act together. They can clean out your whole plant. They have a super chemical cleaning treatment and a passivating agent that inhibits buildup. They even know about filtration.
  4. Look into a chemical treat-ment system supplied by IMS Co., Chagrin Falls, Ohio (, as a possible alternative.
  5. Once you find a chemical treatment that works, rig up a fish-tank pump and circulate the cleaner through your molds once a year. Maybe buy IMS’s apparatus and use the higher-tech cleaner.

—John W. Bozzelli,Injection Molding Solutions/ Scientific Molding, Midland, MIA.

Q. Please explain how different types of gels are formed and controlled in film extrusion. —Global film producer

A. Any defect in molten polymer is a “gel.” It could be a crosslinked gel, a black speck, or unmixed (unmelted) material. On barrier-type screws, if the melt channels do not have the proper aspect ratio and the channels are too deep, which will reduce the downstream velocity, cross-linked gels will build up and cause “showers.” For optical-quality film, a tighter barrier gap in the barrier section should be considered.
—Timothy Womer, global corporate technical advisor, Xaloy Inc., New Castle, PA