When producing parts from hygroscopic materials, desiccant is absolutely necessary to dry the material to an appropriate moisture content. If your desiccant is not working properly, you will produce parts that have exterior visual defects and will have a loss of mechanical characteristics internally (tensile strength and flexural modulus for example). Nylon parts will become brittle, ABS will show silver streaking and Polycarbonate will have black specks.  Ultimately, these defective parts are recognized as scrap.  So when your scrap rates go up, you have to ask yourself, is your desiccant the cause.  Replacing 60 lbs of desiccant costs less than $225. That is nothing compared to the cost of producing bad parts. Most QS9000 and ISO9000 quality systems require replacement of desiccant every 12 months.