How Does Manufacturing Take Advantage of Rheology?

By Robert G. McGregor, General Manager, Brookfield Engineering Laboratories, Inc.

Rheology is the science that studies the flow behavior of materials. The ability to mix, blend, pump, store and fill are processes that rely on data from rheological analysis performed by R&D to evaluate material flow behavior. On the production floor and in the QC Lab, rotational viscometers make measurements that confirm the consistency of the material in process. Typically, these devices make a single point viscosity measurement. They work well, but there is lost time grabbing the sample from manufacturing and getting it to the QC lab for analysis. What if the viscosity measurement could be made directly in the mixing tank or on the fill line before product is packaged? Process viscometers have existed for many years, but few companies take advantage. Why? This article investigates the potential benefits to manufacturing that arise from new investment using “in process Rheology”.

R&D performs characterization tests on materials used in new products (ointments, creams, lotions, elixirs, etc.) before they are processed by manufacturing. Typical tests include “flow curves” and perhaps “yield stress determination”. The former describes how a fluid or semi-solid will behave under variable conditions for flow rate and temperature. The latter addresses the startup conditions when the material at rest is pumped or starts to move due to action of a rotating blade in a mixer.