What I Learned About Dryers

You might not think there could be much more to say about resin dryers than I packed into my magnum opus on pages 58 to 75 of this issue. After interviewing more than a dozen experts, some of whom have spent 30 or 40 years with dryers, I can tell you there’s a lot more to say. (Look for some of it next month.)

Resin drying may be the most devilishly complex subject I have ever bumped into in my 34 years in plastics. So many variables affect drying, and there are so many ways to tweak dryer design and controls to wrestle with those variables. Maybe you thought, A dryer is a dryer is a dryer. Not by a long shot. Is a dryer of Flavor A pretty much the same as all others of that flavor? No again. All of which makes it tough for you folks to know where to put your dollars and your trust. Because if the dryer doesn’t work right, you’re in big trouble. Especially on these hazy summer days.

When you dig into the subject, as I did, you’ll find that dryer sellers are passionately committed to their products. If you try to analyze which of six or seven drying technologies is best for your application, you’ll run into a thicket of conflicting claims without much scientific back-up. It sounds like a lot of he said/she said.

When one company stepped up to fill this gap with comparative performance testing of a wide range of dryer types with different resins, I thought, At last some answers! Its results are presented in this issue, along with warnings by other vendors that the data apply only to the one brand of dryers studied, and not to theirs. I listened to their arguments, and I admitted they had a point. A dryer ain’t a dryer ain’t a dryer. If I had my wish, a lot more suppliers would test their dryers, too. Then we could compare the relative performance rankings of different dryer technologies obtained by each vendor. Those rankings might agree or disagree, but either way we would all learn something—hopefully something more solid than we have today.